text:
How to select and rotate object in blender 3.1 with bpy and python?
I'm trying to select and rotate an object in a frame_change_pre-handler.
Here is the function:
def frame_handler(self, context, dummy):
    self.max_frame = 200
    slow = 45
    axis = "X"
    rotVal = -slow
    scn = context   #->instead of bpy.context.scene, which I tried before
    frm = scn.frame_current
    print(f"current  frame: {scn.frame_current}") #-> this works correct

    cup = bpy.data.objects["cup"]
    print(f"cup name = {cup.name}") # -> this works fine!

    try:

      if ((scn.frame_current > 1) &  (scn.frame_current % 5) == 0):
          print("starting cup  rotation")

          bpy.ops.object.select_all(action='DESELECT')

          cup.select_set(True)
          bpy.context.view_layer.objects.active = cup

          bpy.ops.transform.rotate(value=math.radians(rotVal), orient_axis=axis)

          bpy.ops.anim.keyframe_insert_byx_name(type="Rotation")
          print("cup  rotated")

          bpy.context.view_layer.update()
    except Exception as e:
        print (f"error {e}")

The line with bpy.ops.transform.rotate
gives the error:
error Operator bpy.ops.transform.rotate.poll() failed, context is incorrect

My blender version is 3.1.
Is there maybe a simpler way to rotate an object in blender 3
(like cup.rotate(x,y,z) or so)?
Thank you!
I made a blend-file with some minor code changes:

Instead of:
bpy.ops.transform.rotate(value=math.radians(rotVal), orient_axis=axis)
I tried this:
cup.rotation_euler.rotate_axis('X',math.radians(rotVal  ))
but the error still stays the same.
edit:
maybe I could ask even more precise:
what would be the correct context and how can I set it to the
correct context, so that blender executes the rotation as
desired?

You should modify the object matrix directly instead of using bpy.ops

Thank you. What is the python statement for that?

I was wrong in one point:
the error was not the same with the modified statements,
because I just put the statements into a wrong function.
So this statements
 cup = bpy.data.objects["cup"]
 cup.rotation_euler.rotate_axis('X',math.radians(rotVal ))

already execute the rotation as desired and do not lead into
a context problem.
It would be worth to find out anyway, why bpy.ops.transform.rotate
leads into an error, but this is another question.
I made an update of the blender-file:

which works fine now.


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Spherical / Custom projection at code level
This question is identical to Custom nonlinear distortion lens
With one difference: I'm only interested in a solution at the code level. Because that gives a fine-grained control.
How does one go about doing this?
Here is the setup:

For each square on that grid, a ray is shot out through each corner, returning a colour.  The four corners are averaged, and the resultant colour is given to that pixel. (if there is more than a certain maximum allowed amount of variation between the 4 values, the square is cut up into 4 little squares, and so on, recursively)
That's the standard projection model I'm familiar with.
What I want to do is manually fire out rays myself.
I'm guessing that somewhere low down in the C code level, there is some routine that performs this operation.
But where? Can someone direct me? I would be very daunted to have to hunt it down myself through the Blender source code.
And can this be done in Python? Is there some command for firing a ray and retrieving the colour? If this is the case then I could in theory write my own ray projector, and save the resulting 2D RGB array to file.

It seems someone has implemented a patch which allows you to define your own distortion with a map.

I am not sure if it can be down in Python. But definitely possible in C.
Blender Cycles support non-planar lenses ala fisheye. You can find the user documentation for it on the wiki.
A walkthrough (and patch) from the developer who implemented this feature can be found on Dalai Felinto's website.

I'm not saying it's possible with python, but here's somewhere to start:
1,2.  As a side note, blender's model is to shoot out one ray per square, unless anti-aliasing is enabled under the render panel. With antialising, it uses the specified amount of samples and mixing algorithm.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


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White pixelated domain when viewed in viewport shading
I'm new to blender and am trying to simulate a smoke effect. However, when I try to view the smoke through "Viewport Shading" everything within my domain becomes white and pixelated. Does anyone know the cause and possible solution to this?
Here is a video of issue in motion: https://drive.google.com/file/d/1J2b1xQaF137debneBBMO8TbIHxHDp5rx/view

Make sure to reduce your emission strength

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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Can't find "Add" Node
Maybe it's elementary but I can't find the 'Add' node in Blender 2.82. Maybe you know where it is.

Can you please accept the answer on the question?

This node is on converter -> math and then you can enter your operation, in your case add

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Subdivision Surface Strange face choice?
I have been trying to model a pen clip back and running into a strange effect with the subdivision surface that I do not understand.  For some reason, the interpolated surface is dipping below the original geometry and then bending back up.  I can not figure out why it is doing this.  It is best shown with a picture.

You can see the dip down on the arc to the right side.  I would have thought it would be a smooth transition from the arc to the first set of control points.  I attempted to add some supporting geometry with the highlighted line.  But that did not seem to help.  Any thoughts?  I am just not sure where to start.
Blend File:

Updated Efforts
I have attempted to add some additional geometry.  This has fixed the original issue, but now I am getting some strange artifacts.  I will keep futzing with it but if anybody has a suggestion as to the correct type of supporting geometry I would love the suggestion.  Thanks again for everybody's help.  I learn something new every day.

Your mesh has bad topology. Never use NGons, especially on subdivided models

@DuarteFarrajotaRamos It isn't as much the N-gons in this case as it is the fact that the N-gons in question are non-planar.

That certainly doesn't help either.

try dividing the N gons into Quads using J

I see what you guys are saying.  I will add some other supporting geom and get back to this thread.  I have already tried a little bit but I am having a hard time keeping the added geometry from adding extra visual artifacts to the resulting subdivision surface.  It is hard to strike a ballance.

@DuarteFarrajotaRamos, thanks for the tip.  Thanks to Scott and Henrik also for the pointers.  I have figured this out and posted an answer.

The solution to this problem was to add the correct supporting geometry.  After some fiddling, I have found something that produced a nice smooth output.  What one should look for when this type of problem appears, as suggested by the comments on the question, is NGons.  Although blender has "full" support for NGons, the subdivision surface does not always play nicely.  Although I did not completely get rid of the NGons, I reduced the vertex count and the result is quite nice (I think).  Here is the result:

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Smooth Shading option not working
https://drive.google.com/file/d/1q3kcN4hKMkdARc4XzEbYOsSwoWuhSzKA/view?usp=sharing
Here's my Blender File
I can make the object active.
But when I click the smooth option, nothing happens.

Click on Clear Custom Split Normals Data under Geometry Date,

It looks like most of the faces in the model are disconnected. When you activate smooth shading on disconnected faces, Blender treats each one individually and it looks like flat shading because each face's boundary is handled independently from its neighboring faces.
It's best to model (or import) objects with connected faces if you want to use smooth shading, but here is a quick and dirty way to join most of the faces in your model:

Select the object.
[TAB] into Edit Mode.
[A] to select all vertices.
Mesh > Vertices > Remove Doubles

This will join most of the faces and you will get smooth shading for the most part. You will probably need to manually repair some faces to get it working across the entire object.

Go to Vertex Tab and uncheck Auto Smooth

Go to Edit Mode Press W Remove Doubles
Now u have loose the geometry or unfill Faces
Select all and Press Alt+F
Press Ctrl+N Flip Normals
Now click on Smooth Shading.

This is a better fix than what I offered.

I can just add that for me it was ambient occlusion that gave the illusion of flat shading. Someone else might run into the same issue.

yes me too i just googled about this problem. ambient occlusion was the culprit. but only certain areas got affected by ambient occlusion in my case on my face mesh. does that mean it is bugged?

My issue with 'shade smooth' not working was that I had a bevel modifier. I just removed it and immediately my mesh became smooth. It turns out the the 'shade smooth' funtion was actually applying, it's just that the effects of the bevel modifier had higher priority.

Many times people forget it but you have to select model in object mode and then press shade smooth

I can't believe I was missing that.

I ran into this myself and wondered, why this would happen since my mesh was perfectly fine. In order for the smooth shading to be applied to the entire mesh, you have to select it first by pressing A in Edit Mode.

The only thing everyone is missing and what was in my case is that you need to double check if your normal map image texture is set to non-color color space.

Hi, thanks for the post. This site is not a regular forum, answers should be substantial and thoroughly explain the solution and required workflow. One liners and short tips rarely make for a good answer. If you can [edit] your post and provide some more details about the procedure and why it works. Perhaps add a few images illustrating the workflow and final results. See How do I write a good answer?

Just press F3 and type Shade Smooth


text:
Problem when moving bone
i've been strugglin with my hair paticule on my character , wich i've been attach to the skin and the skin have been attach to some clothes . I finaly finnish doing a basic rigging on the character but when i'm moving arm or else the hair dont move along with the hair (instead move up and down ) . I've been trying to weight paint the vertex group but nothing is happening , only the skin and clothes have been affect by it . Please could you help me out ! Peace !

Please upload modifiers screenshot

When you applied an armature on the particles system based mesh by default armature appeared at the end of modifiers, Please have a look of image below:

Please move up Armature modifier on top of particles modifiers and your hair should be follow the armature
Please take a look of image below:

You may mark the answer as correct, as may be helpful for somebody else.
how to you want to intouch, I usually logged in to this forum daily and also everybody is ready to help :)

Cool man I wish i could found that forum earlier . I'll be asking questions on here then , thanks for your time bro

Welcome and thank you for being so kind, yes this form is very helpful to everybody, I liked too and learned a lot here :)


text:
GPU rendering but task manager shows it is barely being used
The task manager shows I am barely using my GPU. In the render properties I've selected GPU convert. In the preferences>system I've selected CUDA and my GTX1080 is checked. The drivers on the GPU are up to date as well. Is this working correctly?

Task manager has a few different views for GPU usage.  When rendering you don't see activity on the default one.

To add on to the previous comment, in task manager, with GPU selected under the performance tab, pick one of the graphs (Ex: 3D or Copy) and click the little arrow at the top next to the name. Change the graph to Cuda - you should see activity then.


text:
List of constants
In the Blender UI, in every numeric input field, I can enter simple expressions, e.g. 2+4. I just found out that even pi and e are supported values which are then converted to 3.14 and 2.71, respectively.
I was not able to find a list of supported constants or functions. What can I enter there?
Just for clarification, I don't want Python scripting, Math nodes or something else, just these input fields:

Here's a list of all possible math expressions.
Everything behind the python "math." is a valid input:
https://docs.python.org/3/library/math.html

Although listed, tau is not considered valid input

You're right. That's interesting. I can't explain why that is... As all expressions are evaluated by Python, I thought they all would be available inside of Blender.


text:
Embossing an edge-loop
This question follows from Constructing and bevelling a pie-slice
I'm trying to bring definition to the top edge of a solid geometric object.
EDIT: I'm trying to achieve something like this:

... The important thing is that the edge is clearly defined, rather than exactly how it looks. So I'm interested in any technique for doing this. I'm focusing on this one because it's the only one I currently know how to do.
First I go into edit mode, edge-select, CTRL+RightClick to select an edgeloop, and create a vertex group:

Then I attempt to apply wireframe modifier:

As you can see, it doesn't work.
However, if I try the same technique on a cube, it does work. (I've included the cube in the picture, although it isn't the best screenshot, sorry about that).
How to get this effect working?
And is there any other technique to bring the edges out? Could I somehow extrude a square/hexagon through that entire edge loop?
Someone on IRC suggested bézier + Bevel-object. I like the sound of this, but would I have to first create the curve, and then independently create an object for the border using bevel object, and then create the actual solid object by extruding the curve downwards?

could you add a sketch or photo of what to want to achieve?

Sorry, I've added an image and a little explanation. The main thing is to get a well-defined border rather than exactly how that border needs to look.

From your description it looks like you have found a problem with many of Blenders tools.  If you change an objects location and dimensions in Object mode then a lot of other tools will fail to function properly.  Several tools have been updated to fix this but not all of them.  Try to remember to alter your model in Edit unless it can avoided and also remember this shortcut(in Object mode)  Ctrl-A, to use 'Apply -> Rotation and Scale', also 'Apply -> Location'

One way to do this is by beveling, then extruding:

What I did in the gif:

Enter edit mode (Tab)

Enter face select mode (CtrlTab> Face)

Select a face on the surface that I want to select, then press CtrlShiftAltF to select the entire surface.

3D view > Header > Select > Select Boundary loop:

Bevel (CtrlB)

Extrude and cancel transform (EEsc) See this question for details on what pressing Esc does.

Press AltS to scale along the normals.

Thanks for the edit, I was struggling with the original GIF!


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In Python, given x-value on 2D Bezier Curve, return y-value
I am attempting to create my own transfer function.
So first I draw a curve:
3D View > View > Top
Info > Add > Curve > Bezier
Tab to enter Edit Mode
Curve Display > Normals > (off)
Properties > (Curve icon) > Shape > 2D
Create the curve using:

RMB to select waypoints or control points
G to move them,
Select last waypoint, E to 'extrude' i.e. add another waypoint,
or
Select two adjacent waypoints using RMB and ShiftRMB > W >

So now I have my curve:

How do I now, from a Python script, retrieve the associated y-value for a given x-value?
P.S:
This question follows from: Create custom graph and access values from Python but I realised that trying to hijack the keyframe animation curve editor for this purpose is trying to get a square peg into a round hole.

I think your asking the wrong question. Any number of curve points can have the same x value, you want the y value from the same point that you get the x value. That should entail changing .x to .y or [0] to [1]

This works a little bit differently from graphing in math class.  There has been no formula defined for that shape you've created.  You can't get 'y' by plugging 'x' into a formula, because no formula has been generated.  Besides, both 'x' and 'y' have already have been defined when Blender created each point so you'd be calculating something which is already been calculated and stored in memory.  Memory access is much faster than recalculating.

The following script uses the formula for cubic Bezier curves (which Blender approximates) to first determine t (which is the parametrization of the curve) from x and then gets y from t.
import bpy
import numpy as np

def main():
    '''Here's an example usage of these functions'''
    x = 5.0
    bez_obj = bpy.data.objects['BezierCurve']

    print('The y-value is', getYfromXforBezierObject(bez_obj, x))

def getYfromXforBezierObject(bez_obj, x):
    '''Given a Bezier object which, when projected on to xy-plane, is a
    well-behaved function (i.e. each x-value has only one associated y-value),
    this returns the y-value for a given x-value

    The higher resolution your curve is, the more accurate the resultant y-value
    will be.'''

    #find appropriate segment
    segment_i = determineBezSegment(bez_obj, x)

    if len(bez_obj.data.splines) > 1:
        print("WARNING: your Bezier object has multiple splines!")

    spline = bez_obj.data.splines[0]

    #get the four points that control the cubic bezier segment
    P0 = spline.bezier_points[segment_i].co[:2]
    P1 = spline.bezier_points[segment_i].handle_right[:2]
    P2 = spline.bezier_points[segment_i+1].handle_left[:2]
    P3 = spline.bezier_points[segment_i+1].co[:2]

    y = getYfromXforBezSegment(P0, P1, P2, P3, x)

    return y

def determineBezSegment(bez_obj, x):
    '''Given a Bezier object and an x-value, determine which of the cubic
    segments corresponds to that x-value.
    A return value of 0 would represent the first segment.'''
    print(bez_obj.data)
    bez_points = bez_obj.data.splines[0].bezier_points

    if len(bez_obj.data.splines) > 1:
        print("WARNING: your Bezier object has multiple splines!")

    #loop through all segments and find which one contains x
    for segment_i in range(len(bez_points)-1):
        start_point = bez_points[segment_i]
        end_point = bez_points[segment_i+1]
        #break if this segment contains x
        if start_point.co[0] <= x < end_point.co[0]:
            break
    #check if no segment was found
    else:
        print("WARNING: no segment found for given x-value and Bezier object")
        return None

    return segment_i

def getYfromXforBezSegment(P0, P1, P2, P3, x):
    '''For a cubic Bezier segment described by the 2-tuples P0, ..., P3, return
    the y-value associated with the given x-value.

    Ex: getXfromYforCubicBez((0,0), (1,1), (2,1), (2,2), 3.2)'''

    #First, get the t-value associated with x-value, where t is the
    #parameterization of the Bezier curve and ranges from 0 to 1.
    #We need the coefficients of the polynomial describing cubic Bezier
    #(cubic polynomial in t)
    coefficients = [-P0[0] + 3*P1[0] - 3*P2[0] + P3[0],
                    3*P0[0] - 6*P1[0] + 3*P2[0],
                    -3*P0[0] + 3*P1[0],
                    P0[0] - x]
    #find roots of this polynomial to determine the parameter t
    roots = np.roots(coefficients)
    #find the root which is between 0 and 1, and is also real
    correct_root = None
    for root in roots:
        if np.isreal(root) and 0 <= root <= 1:
            correct_root = root

    #check to make sure a valid root was found
    if correct_root is None:
        print('Error, no valid root found. Are you sure your Bezier curve '
              'represents a valid function when projected into the xy-plane?')
    param_t = correct_root

    #from our value for the t parameter, find the corresponding y-value using formula for
    #cubic Bezier curves
    y = (1-param_t)**3*P0[1] + 3*(1-param_t)**2*param_t*P1[1] + 3*(1-param_t)*param_t**2*P2[1] + param_t**3*P3[1]
    assert np.isreal(y)
    # typecast y from np.complex128 to float64
    y = y.real
    return y

if __name__ == '__main__':
    main()

This script will work only if your Bezier curve is a function when projected into the xy-plane (hit NUM7 and make sure it passes the "vertical line test").

Blender 2.70 should actually come with NumPy on all platforms. Correct me if it's not the case for Mac OSX, but the Windows builds definately ship with the numpy size-package.

Thanks Garrett, this is fantastic! I'm trying to put this function in its own module http://blender.stackexchange.com/questions/8496/how-to-create-reusable-python-component

@Garrett Just a thought.  Using the letter 't' as a variable makes the code difficult to follow and makes searching very difficult since the 't' comes up in a lot of words.

There is a utility function to interpolate a bezier spline segment:
from mathutils.geometry import interpolate_bezier

API docs: mathutils.geometry.interpolate_bezier

I can't see how to throw in an x and get out a y. It looks as though I have to throw in a t and get out an xyz. In which case I would need to write quite a messy algorithm to repeatedly bisect t depending on whether the x from the returned xyz is greater or lesser than the target x

Actually, it can be solved analytically although it might be a huge mess. This is because Blender uses cubic Bezier curves and cubic polynomials can be solved analytically.

@Anyone, feel free to correct me if I'm wrong:  't' is probably an array of addresses which means that t has many values;t[0], t[1], t[2], etc,...   For a curve with 3 points it might help to think of 't' as being a container that holds 3 more smaller containers, one for each point and each small container has 3 slots, the 'x', 'y', and 'z' values for each point


text:
Straighten loop edges on a rounded object
I'm trying to make these loop edges straight around this rounded cube so I can easily place a shrinkwrap-like packaging and make it look good.
I tried changing the size using different methods or sliding them but I can't get them to keep the curvature of the object.
In yellow, the edge loops I have now:

In pink, how I'd like the edge loops to look, but keeping the main object curvature:

Did you try to select one loop and hit s, z, 0? Assuming your image is in front view.

Yes, that's the first thing I tried but the vertices move off the main object curve, what I  would like is to slide the edge but it doesn't look good either. I haven't found a solution yet but I should probably find a different approach when modelling.

You can use the Knife Project tool, to cut a new edge loop.
It will perfectly follow the object's curvature.

Add a plane and position it where you want the cut
Select the plane first and then your object
Go to edit mode and use Knife Project with Cut Through checked.

Note: The cut depends on your current view - front/side orthographic works best.

As Robin Betts kindly pointed out, it's better to put the cutting geometry outside of the object, which allows to cut multiple edges at once.
Projector parallel to viewing plane...

Here, a grid with its faces (only) deleted

.. so multiple edges cut simultaneously.

Thank you! I tried the first option on my own first but even though it looks like it keeps the curvature, it does not when you turn the object around.
I will try the second one but it seems I should probably model the object again thinking how the UV will wrap first though.

Happy to help. If you get stuck anywhere, feel free to ask :).

Thanks again, that's exactly what I needed, the knife project tool worked wonders :)

@JachymMichal         Absolutely nothing wrong with your answer, (UV'd) but it's unusual to have the projector in that orientation: see suggestion

@RobinBetts Thanks for pointing that out, you're right :). No idea why I used it that way. Let me borrow your images to improve the answer...


text:
Add walls to 2D floor plan
I have the blueprint of a room in my flat as a planar 2D vertex, example:

I want to add walls to it that are going into the Z direction. I have tried several modifiers and searched with Google, but i have not come up with a fast and easy way to do it. Currently my method is to create a new, second vertex and measure all edge lengths, then recreate the shape and extrude it into the Z direction. There surely must be a better way, maybe with a modifier -- but  how?

u can go with the addon called archipack & archimesh or solidify modifier or with intersect

There is paid add on available to speed up wall creation. It's called Quick Wall

Inset the face you have with I, invert the selection (since the area which was inset will remain selected) with Ctrl+I and then extrude.

Note that depending on the case you might need to change topology in the end to convert Ngons to something more appropriate. Though if no subdividing with modifiers like Subsurf is used then it won't be that necessary.

Actually that was one of the first things I tried. The downside is that you have to construct the geometry to a larger scale because inset will shrink the faces. That is a huge downside if you have exact measurements. Additionally, the geometry is not that great because of the diagonals at the edges (that wouldn't be a gamechanger for my use case, tho).

@hochl the only way to create geometry of the walls connected to the floor is to extrude them somehow. I don't have any idea regarding larger scale, if you have any trouble with some more complex case then provide it in the question. There is Offset Edges addon for more precise extruding/offsetting them, see https://blender.stackexchange.com/questions/1088/is-there-a-way-to-offset-an-edge-extrude-edge-loop-perpendicular-to-each-edge


text:
Unexpected physics behavior with copied objects
I try to copy a uvsphere which has basic
physics behavior: rigid body, collision mesh.
The spheres should just fall down onto a plane.
The code to create the copies is here:
def selectSingleOb(self,name):
    ob = bpy.context.scene.objects[name]
    bpy.ops.object.select_all(action='DESELECT') # Deselect all objects
    bpy.context.view_layer.objects.active = ob   # Make the cube the active object
    ob.select_set(True)
    return ob

def startUp(self,n):
    self.nObjects = 3
    self.spheres = []
    zOffs = 15
    sIdx = 0

    for i in range(0,self.nObjects):
        sphere = self.selectSingleOb("Sphere")
        bpy.ops.object.duplicate(linked=False)
        newSphere = bpy.context.active_object
        self.spheres.append(newSphere)
        newSphere.rigid_body.collision_shape = 'MESH'
        print(f"newSphare rigidBody collision: {newSphere.rigid_body.collision_shape}")
        bpy.ops.transform.translate(value=(0,0,zOffs*sIdx))
        sIdx = sIdx + 1

The translate-operation should just ensure, that the sheres fall down one after each other.
Now the strange result is, that the first generated sphere (sphere001)
does not fall down from top to bottom, it has a
drift to one side. The original sphere and the other copies (sphere003 and sphere003)
do behave as expected.
Is anything wrong with the generation of the copies? Are there some data
not copied but randomly assigned??
The falling of the sphere is not only unexpected, it
is strictly-speaking wrong. I'm not very experienced
with physics simulations, so I don't know how to
simulate a side motion for a sphere when falling down
with blender physics parameters !??
The blender version I'm using is blender-3.2.2-linux-x64
with Ubuntu 20.04.
The blend file is here:

It seems that I have found the solution: The first copy apparently collided with the hidden original cube. My initial attempt to hide it:
    sphere.hide_set(aState)
    sphere.hide_render = aState

did not exclude the original from the animation.
It additional needs a hide from viewport:
sphere.hide_viewport = aState

Now all copies fall down as free falling spheres should.


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Rotate each instance in specific direction
I created a hexagon with a circle curve. Then I instanced arrows on each point. I want to rotate each arrow to point along the edge of the hexagon. How would I do that? A similar question was asked here but the Align Euler and Rotate Euler node is deprecated and using the Rotate rotation node does not allow me to restrict the rotation to only the z-axis

Use the "align euler" node.

Align Euler is depricated

Sorry, I meant "align rotation".

Use align rotation to vector taking from the curve tangent.
But since the tangent on the points is interpolated, the arrows will be between each side.
So we sample a factor (which goes from 0 to 1), where we divide the point index by 6 sides, and add 1/12 to reach the middle of the side.
(Multiply the tangent by -1 to invert)
PS: these cones are pointing to Z, if your arrow is not pointing to Z, change the axis in "align rotation".


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Camera constrained to path, not follow it exactly around curves
I have my camera constrained to a curve with Follow Path and it stays with its origin on the path exactly. But when I add a strong curve to the path the camera starts going off the path. It is cutting corners for some reason. Has anyone had experience with this problem?
I found I can make the path I want and then select all the points in edit mode and subdivide them until the camera comes back to the path on strong turns. But this is not a functional solution if I want to quickly edit the path later.

Perhaps you have the curve resolution set to low? The curve will render at the preview resolution when it is set to zero. This will make any objects tracking its length cut corners as they evaluate the curve in a parametric manner.

vs


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How do I do a fluid splash in blender
I tried to make a splash with fluid following a tutorial but something went wrong and I cant figure it out.  Heres what its doing on the video link.  How do I fix it?

This is a link to the place on your physical volume (computer). We cannot access it. Please add some screenshots and be more descriptive.

Sorry about that, I don't know how to add a video.

There is no option to add video here. This is why you will need to add screenshots and describe your issue in detail.

Ok I'll fix this.

I made it a gif, so I can show the problem

In the fluid world properties what is the real world size? The default is 0.5 meters.

Apply scale to the objects, this should help.

The real world size is on 0.5

What do you mean by apply scale to objects

https://docs.blender.org/manual/en/dev/editors/3dview/object/editing/transform/clear_apply.html - Apply paragraph.

I feel like a broken record here.. but please use this website to let us see your file and test to see if the error occurs on our side. https://blend-exchange.giantcowfilms.com/


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Render image becomes tranparent with more samples applied
I was trying to create some bubbles. Everything was OK in render preview, but render result becomes completely transparent image.

Here you can see render preview. I use HDRi lighting and film transperant.
First sample in render process shows a bit of "envelope" of each bulb.

Here you can see render at 2-3 samples and it's almost invisible.

here is a gif when render runs...

Here is my node setup. I can upload my .blend file if you help me how to do this:)
Yes, bubbles are visible, but it brings black background and some bugs.
And the most interesting thing i found when i tried to save this image with black background without alpha.

THIS is the saved rendered image from previous screen!
Here is the comparison between rendered image and render preview at 1 sample.

And at 2 samples.

Is this possible to fix camera or rendering setting to get rid of the problem??? I don't really want to change my node setup because i like how it looks....

Are bubbles visible if you put channels of the image in UV Image editor to RGB without Alpha? (buttons to the right from the Image selector).

I don't see how 'more samples' makes the image disappear if you are using the same amount of samples for the preview and the final render?

Yes bro, this is the save problem. I can see my bubbles if i use alpha over node with black background.... Thank you.


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Weird infinity polygons appearing
Recently I've been having some odd problems in Blender. Whenever I open a file and select an object, odd faces seem to appear that stretch to infinity.
This occurred on my old PC, both in Blender 2.79 and experimental versions, and now my brand new PC.
Whenever I select an object, nothing happens yet, but as soon as the camera is moved the polygons appear. They also appear for every object, and are different for each object.

Any suggestions to remove this error would be greatly appreciated.
Hardware specs:
CPU Core 7900x
64GB Ram
Nvidia Titan X (Pascal)
Nvidia Driver 388.31
Latest official Blender release (2.79)
Thanks!
PS: It also appears when opening the default scene with just a cube and a camera.

nice chainsaw anyway.

I'm already using the very latest nvidia drivers, as mentioned in the post. I don't think there are any newer ones available, at least not for the Titan X Pascal.

Do you have any ideas about "when this problem started"? I myself experienced hardship after update of Windows. It was solved by updating my GPU driver online. (as your driver is the latest, it might be off the point)


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Randomize wave texture rotation
I have followed the setup in  and got the expected result (bottom part of image).
However, if I duplicate the sphere, all the spheres will have the same colour and same wave texture (say, 2 of the blue spheres in the above image - but not, one whose wave texture is rotated - eg. the blue and yellow spheres have a wave texture that is slightly rotated).
I am able to have a different colour for the spheres (by using object info and color ramp), but I do not know how to have each sphere's wave texture have a different rotation.
Initially, I used randomize transform (specifically used a random rotation), but did not have any effect on the wave texture (the objects are rotated, but the wave texture isn't).
I then used a mapping node as in the following:

connecting the vector output of mapping to vector input of wave texture (and changing the rotation of the mapping node).
This does change the rotation of the wave texture, but I have to manually specify the rotation and each sphere needs a new material.
So how do I have a single material that has a random rotation on the wave texture?
EDIT: I tried to "group the above node tree, apply it on x and y values (just as above) then the output of that applied on the x and z and finally the y and z", but none of the combinations work as I would like. I have linked to a blend file containing my trial and errors

You can use the Object Info Random Output as an angle for rotation of the texture in one or more axis. I understand your problem is that the mapping nodes doesn't have input, you can however use rotation transformation matrices to compute the vector manually, in one axis (z), it looks like this:

In three dimensions you can use the 3D Rotation Transformation Matrices to get:

The node tree is big, so here is the file to study it:

Wow! That seems like a complicated node setup. I'll try it and get back to you

@peqhusus The number 60 is arbitrary and it acts as a seed for randomness, just don't make it too small.

The texture now has a good-enough random rotation around the global z-axis. Is there any way to also have the texture rotate around the x or y-axis randomly? (so that the band are not all latitudinal, but some longitudinal, and some a mixture of both - eg. diagonally)

Then for 3D rotation, would I use [x,y,z] multiplied with https://wikimedia.org/api/rest_v1/media/math/render/svg/a6821937d5031de282a190f75312353c970aa2df ?

@peqhusus Yes exactly. Matter of fact, if you group the above node tree, apply it on x and y values (just as above) then the output of that applied on the x and z and finally the y and z it will give you what you want.

I have tried to do what you said above (blend file: https://blend-exchange.giantcowfilms.com/b/3972/) but I cannot get it to work. Can you take a look and tell me where I made a mistake?

@peqhusus I added an example file for you.


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Simple fan with single bone / weight paint doesn't appear correctly while posing
So I'm trying to create a simple fan like object that folds up from right to left.  You can see my single bone along with how I painted the weights below:

And here is the result when I go into pose mode and rotate the bone 90 degrees.  I would expect left side vertices to be influenced less so that the entire object can fold into itself.

If you have a vertex that is controlled by only one bone, even if the weight of this bone on this vertex is 0.01, the influence will be 100%.
Example: I have this square, the bone has a weight of 0, 0.01 and 1 on its 4 vertices:

If I move the bone, the vertices with a weight of 0.01 will move as much as the vertex that has 1, the vertex that has a weight of 0 won't move:

So if you want to vary the weight of a bone on a vertex, you necessarily need a second bone. If I create a second bone that has a weight of 0.01 on the vertex that has already a weight of 0.01 from the first bone, this second bone will share a 50% influence on this vertex.
For your object, you could create a series of bones, for example 5 bones, parent the object to the armature With Automatic Weights, then give your bones number 4, 3 and 2 a Copy Rotation constraint with bone 5 as Target, and a decreasing influence of 0.75, 0.5 and 0.25:

Here is what it gives:

oops sorry Robin, I hope I didn't delete your edit  ;)


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connecting these two meshes together
I want to neatly connect these two meshes together (the spokes on the rim)?
How can I do this?
Hi everyone, I made a new rim and did what you say, but if I want to bridge the short sides it will be somehow crossed (see photo). Tried everything but couldn't get it done. What am I not doing right?

Hello :). What have you tried so far and where exactly are you stuck?

it would help if we could see the topology, because it may allow you to simply use bridge edge loop for example

First, join your 2 objects with CtrlJ.
Then you can use the LoopTools > Bridge. First thing, open the Preferences panel and activate the addon called LoopTools, then:

Bevel the inner edge loop, cut a hole:

Select the edges that you want to bridge, right click > LoopTools > Bridge:

Tweak the factors in the Operator box (Segments and Strength):

OP (or future user) might not have loop tools activated... worth adding a note on that :)

oh yes you're right, I'm going to edit

Quite likely, OP needs to join the meshes first. (Select both objects and press CTRL+J)

oops you're right too

Thanks, I understand what you mean, that means I have to redo the rim to make the edges match the spokes.
It is namely 5 spokes.

you can use Array + Simple Deform (Bend mode) modifiers to do the wheel, it's a non destructive method

Hi everyone, I made a new rim and did what you say, but if I want to bridge the short sides it will be somehow crossed (see photo).
Tried everything but couldn't get it done.
What am I not doing right?

hard to say, maybe share your file: https://pasteall.org/blend/

Hello, it worked, I forgot to remove the faces from the rim where the loops go :)
Thanks everyone !


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Interface problem (Sticky windows)
The following interface problem occurs,
The UV Image window is attached to the Properties window, if I make the Properties or the UV Image window larger or smaller, the UV Image or Properties window will go along (see photos).
Blender interface-01.jpg - Blender interface-02.jpg
How can I solve this ?

Yes if the windows are at the exact same level they will stick to each other, I don't know if there's any other way to solve it than to create a new window and collapse it, like that:

You could join the areas but I doubt it makes it faster as you'll need to create a new window:

Thanks, it works fine again !


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How to retopologize mouth of my character?
I'm retopologizing a mesh I sculpted and ran to a problem with retopologizing the mouth cleanly. The first time I retopologized it, it looked way too messy so now I'm redoing it, but I don't know how to do it cleanly.
How would I retopologize the teeth (the bumps) correctly? Are there any retopology strategies that I should be using for this?
Notes: Shrinkwrap and Subsurface modifiers are on

Messy previous attempt

Current attempt

Current attempt (in edit mode)


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Error in exporting .pod with PVRGeoPOD
I'm using PVRGeoPOD trying to export a model with simple rotating animation, however, I kept getting this error message. Wonder if anyone came across this and could give me a hand. Thanks a lot.
Blender file attached to the post.

I would recommend asking on the author's site. Typically when addons don't work, we can't help much.

Did you get an answer for this ? I'm facing the same issue. I tried to export a simple cube and there was no problem. I had this problem when I was exporting my scene.

Okay, I figured out something that worked for me but I haven't found the root cause of the problem. I wrote a script to extract vertices and faces data. Then I re-created the mesh using this data of vertices and faces using from_pydata feature in a new blend file. I then triangulated the whole mesh. The export worked now. I went back and tried triangulating my old mesh in the old blend file but that did not work. Only the new triangulated mesh in the fresh blend file worked.

I don't think it has anything to do with cycles engine or blender internal engine. I was working on Blender Internal, and I came across the same problem

Hey, I asked on Imgtec and eventually got an answer :D Check this link out: https://community.imgtec.com/forums/topic/blender-pvrgeopod-plugin-wont-export/

According to Imgtec, the problem is not all meshes are triangulated. This python script fixes that.
Full discussion here.


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Rendered mode all black
I'm trying to render this underwater scene, but somehow, I can only get this much to show:

Here is my suspect: I was following a part of this tutorial: 18 ways to speed up cycles rendering and I only reduced light bounces, changed tile size and used the denoiser.
However, I retraced all those steps but they don't seem to be the cause. I really try to not overlook anything, though.
So, I don't know exactly what I did wrong (otherwise, I wouldn't be asking for help). So I would really appreciate if you can suggest how I can solve this.
I also read other similar threads about rendering all black, but haven't found anything that could apply to my case.
Here is the blender file.

Appreciate any help, TIA!

Thanks! That node was leftover from a tutorial that didn't work. So I deleted it. However, now if I render I can see the green patch of the pond but everything else is still black. So the issue is still there...

Yes, of course. Sorry cegaton, I was panicking a little and didn't have a clue. For the past hour I've been trying to solve this problem so I'm updating my question now.


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How do you create a string of numbers using repeat zone
How do I iterate from 1 to 3 instead of three 1's? I want the value going into the String to Curve node to update with each iteration. I know how to do it with the Simulation zone by combining it with a Scene Time node and feeding the frame number into the string to curve node but I don't know how to do it with the Repeat zone.

It's very simple, just mantain a counter - you can even join strings instead of geometry to only convert string to curves once (and get the benefit of kerning, word wrapping etc.)

Excellent! I didn't know you could create a counter, but I figured it out. Thank you!


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Blender bones not effecting the mesh correctly
I made a gun for my character, I tried to add a Hand Holder bone to my character rig to be able to move the gun as the characters hand moves.

And I parented it in a way that the Hand Holder bone was effecting the gun 100%. but the problem is that the gun mesh is not in the Hand Holders position and it has some offsets :
I researched google for any answer but the only thing I found is by changing the weight of the bones which doesn't worked.
I tried doing weight painting and resetting the position of the gun, and none of them worked for me.
blend file :

do you want it like that? [1]: https://i.sstatic.net/y9kAX.gif

Exactly like that @Chris

delete the parent and the armature modifier of your gun

select your gun in object mode

shift select the armature of your man, go to pose mode and select this bone

CTRL P -> Bone

go back to object mode and rotate/move your bone that it fits in hand

result:


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Blender how to add local rotation keyframe
I made a car model and then I animated it. I found that the wheel are rotating wrongly in world space :
Wheels are childs of car.
By researching I found that it`s somehow because the wheel are animated in world space.
So I think by changing it to local space ring will rotate correctly.
I tried adding armature and make wheel rotate with bones but it didn't worked for some reason.
And I also tried other keyframes of blender like Visual Rotation but it had same resault. And I'm looking for something like Local Rotation in insert Keyframe window.
blend file :

select all four wheels

Go to frame 1
Hit A here so that all gets yellow:

Hit X -> delete keyframes
Now hit I when hovering over delta transforms -> rotation

go to frame 150
enter -360*3 in x, then I to insert keyframe

result:

repeat that for all wheels and use z rotation of delta transform to drive the curve.


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Iam not able see the vertices when dragged it down

File Link:
-->
I am a beginner at blender, I trying to do a donut which I saw on YouTube(blender guru).
I dragged the vertices down and then I saved(not sure) it. I am not able to see the dragged vertices, dear Blender community help me with his

I don't know how you dragged them exactly, but obivously you cannot see them because they are inside the other mesh. So it looks as if you not just dragged them down but inwards as well. Now you have to drag them out again.

Press Z > Wireframe to see the wires. Press Alt-Z to see through geometry. That way you can select the vertices easily.

it looks like your vertices are just behind the faces of the donut, you have enabled the Snap option so they should stick to the surface but maybe you haven't followed the instructions correctly, hard to say, maybe share your file: https://blend-exchange.com/

@moonboots I updated the question along with the file. Review it

The vertices of the icing are behind the faces of the donut. To fix that enable the Face Project option of the Snap:

Press AltZ to see the vertices, select them, AltZ to exit transparency, move the vertices, they will stick the faces of the donut, and back to Object mode:


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Create a concave shape from a circle SVG
I need to create a concave shape from this painted circle that looks like a saucer.

Hello do you mean that each shape is supposed to be hollow, or to be a hole?

hello there thank you for ur comment and yes i want it ti be hollow lets say like a dish or a pendent

Import your image as Image > Reference then convert Trace Image to Grease Pencil (note that the new object will be overlapping the image so you need to move the image to see it):

Now convert this object to bezier curve (again, move the former object in order to see the new):

Convert the bezier object to mesh:

Clean the object (remove the double stroke and the circle):

Create a filled circle object, put it behind the pattern object, switch it to Edit mode, CtrlLMB to select the pattern object and use the Knife Project tool:

Result (X > Delete Faces to get holes):

it worked thank you, still have a problem in concave it like a dish or half sphere

what do you mean? Please edit your original question and show a screenshot

Follow moonboots' instructions to create mesh, turn on proportional editing at the top of the screen, switch the mode to "sphere", select the center vertex or vertices (you may have to subdivide to get more vertices, right click and select subdivide), and drag the vertex/vertices down with the 'G' key to create a concave shape.


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Why does a face on one side of the cube not go with the vertex?
This has probably been asked, but I am not good with the modeling lingo yet so I have no Idea how to search this.
Why does a face on one side of the cube not go with the vertex? Its fine on the one side but on the other the face gets outside the edge.

Can someone explain or link why this happens please.

Related - https://blender.stackexchange.com/questions/5073/edit-face-triangulation-without-actually-adding-edge

This is happening because of the way polygons are displayed. In order for the geometry to be displayed it needs to be triangulated as video cards draw only triangles behind the scenes(math is easier this way and pretty much all computer graphics currently are built on that). There are two ways to triangulate the side faces in your example:

What we are observing here is automatic triangulation algorithm failing to guess what kind of triangulation is desired in this case.
Errors like this will happen from time to time if you have concave n-gons. The best thing to do here is to get used to not having them in your geometry.
You can solve the issue manually connecting vertices of any concave geometry to make them convex as you can see in the GIF. If it happens that you need an automatic way to fix these issues you can also go to the Mesh menu in the header of any 3D View panel and choose Clean up -> Split Concave Faces while you have everything selected in edit mode:

You have a 4 sided square that is folded almost in half, this is to be avoided when modelling.
What should be done instead when you start with the cube is to subdivide those bent faces into triangles first. Select the 2 vertex between where you want the square faces to bend then press J then repeat on the other side and there are the lines you are not getting.

imho the question is asked because on the other side it's different, and is as expected...

and if you keep just the "good" face, and extrude it on Y, the same shape comes out different, ie: with looking good faces...

@m.ardito  Got it. So the fix is very easy. But as  m.ardito said I dont understand why it doesnt happen on both sides?

@GašperSkrt You are doing something that is confusing to Blender so it won't display it properly.


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Blender 2.8 not rendering video
I am splicing several clips together with audio. Everything plays fine in preview. I have set the start and end frames, changed the format to ffmpeg, container mp5, codec h264, audio codec aac, everything else default. When I click render animation the screen pops up grey and there is no progress bar at the bottom of the main screen. Under tools, I checked all the slots and it says image won't load. So far I have tried changing the viewpoint to zero and tried without the audio. Nothing is saving to the output location.
Blend location:

Are you talking about VSE? Do you have checked Output Properties > Post Processing > Sequencer? If so attach simplified blend via https://blend-exchange.giantcowfilms.com

I added the file to the link. I do have the sequencer box checked.

I cant reproduce your issue with provided file. It renders output. You could keep just a first strip, just to see a blend and video example. Since there is not any video I cant say what is going on. I placed just a color strip and my video to see, but I cant test without video example. Isn't that like you changed location and video was played from cache?

Thanks vklidu, it was something to do with the file location. I resaved it under a different name and changed the output folder. I'm rendering now. Thanks for the help.

OK, Great you solved it :)


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Why do black spots appear on my render?
So I was following a tutorial on YouTube on How to make light bulbs (by Blender Guru) but when I did the render black spots appeared on the filament
. AND They don't look like noise AT ALL.
You can see them on the glowing bulbs filament and the glass cylinder thing.
Why do they appear and how do I get rid of them?

enter image description here

These are my settings

Laldhinthara, could you add a little more information? May be attach your blender file (use https://blend-exchange.giantcowfilms.com/) or add screenshots of your render settings (Samples, denoising...) and material setup? This way you would increase your chance of getting an answer.


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How to remove extra animation actions in blender?
I usually make extra actions accidently. and the problem is that they always make my project untidy and I don't know how to delete 'em.
I searched in google but I didn't find any good way for doing this.
I already checked out Edit/Preferences window but I didn't find anything for deleting actions.

Go to the action editor. Use the dropdown menu to select the action.  Make sure the 'shield' is not checked, and click the x to delete, iirc

In the Outliner, click on the Display Mode icon (1 below) then on the Orphan Data entry (2).

Expand the Actions entry and you'll see your list of actions with a 0 against any which aren't used. You can then right-click on the unwanted ones and delete them using X.


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Blender IK constraint not working correctly
I made a rigged character but when I wanted to add IK constraint to it, the rotation of bones became confusing :
I searched youtube for the answer but the only thing that I found is changing the Pole Angle of the IK constraint.
I did it but the foot bone was steel in wrong direction.
I also tried changing the role of bones. and none of them worked.
Blend file : .blend file

In Edit mode, move the knees and the pole targets a bit forward. The knees need to be bent a bit so that Blender knows how the legs are supposed to bend, and for the moment your pole targets are too close to the knees. Once done, correct the Pole Angle to something around -100°.


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how to batch find and replace bone by regex with multiple name list
I try to make my own bone rename list for Daz3d character to Ue4
by using Blender's batch rename tool with regex.
The outcome I want is to change bone names separately in a list, for example:

abdomenLower → spine_01 and
abdomenUpper → spine_02 and so on.

I use a setting that works in Notepad++.
The search for is (abdomenLower)|(abdomenUpper) and the replace with is (?1spine_01)(?2spine_02).
But in Blender, it works only the search phrase. The replace phrase just replaces both matches with (?1spine_01)(?2spine_02) and (?1spine_01)(?2spine_02).001.
Does anyone know the proper regex for the replace phrase in Blender?

Have a look at the linked question above. The first matched group for the regex is referenced by \1 not by ?1.

thank you blunder

but the outcome still not what I want.
now the bone name is go
(spine_01)(abdomenUpperspine_02)
(abdomenLowerspine_01)(spine_02)
what I want is to change it seprately
abdomenLower > spine_01
abdomenUpper > spine_02

Sorry, then this is not a duplicate and solves only a part of your problem. I've voted to reopen it again. -- I've tried your example in Notepad++. Is the replace with correct? Shouldn't it be (?1spine_01)(?2spine_02) without the |? Because with the | the replacement does this: abdomenLower -> spine_01| and abdomenUpper -> |spine_02. -- Blender might use Python regex? (not sure). But if it's not possible to use regex then you still can use a script in Blender.

yes it's not with the | . I just copy the wrong one by my experiment. sorry about that because English is not my native language so I always use copy a lot. I will re edit the question. Also at this point I also think the batch rename will not work with notepad++ solution because how it design. And phyton script is beyond my understanding.

but actually I already use other third party batch script that someone already make long time a go to rename these bone by covert the .fbx file.
it's just not comfortable to do it when you edit the model a lot of time and reimport it


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I can't paint the model with Texture Paint
I can't paint the head model I made with Sculpting with the Texture Painting panel. But I can paint on another model. What is the problem here?
Link: https://dosya.co/yu74boitf245/yaratık.blend.html

In the file you share you haven't given any material to your object (and in that material you need to create an Image Texture with a new image)

sorry i posted the wrong link.

@moonboots The link has been updated. I reloaded the project.

Can you check the link? I can't paint over the head.

sorry I can't test your object, it's too high in polygons, do you really want to paint on this object? You should better create a low-poly before, and bake your high-poly to the low-poly, then paint on the low-poly


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Objects appear dark
The ceiling looks very dark. How can I make it light? The lamp and wall textures on the ceiling are not visible.
Work file: https://dosya.co/5u4m5wadulp1/calisma.blend.html

Ceiling shader panel

Lamp shader panel

hello, could you please show the Shader Editor or share your file?

I shared the shading panel

I also added the link of the file.

it would be helpful if you do file->external data->pack resources before uploading your file...

As Chris says, it's hard to tell because you haven't packed your images. Also, switch the Image Texture from sRGB to Non-Color for the normal maps

Even without having those textures in the file I would say, the lamps are all shining downwards and since I don't know without textures how dark or bright the floor is it's hard to tell how much light could be bouncing off there to light the ceiling. Or do you mean they are completely invisible...? Maybe because you are in Solid View instead of Material Preview or Rendered View?

@GordonBrinkmann I shared the ceiling and floor image now

@user17987086 Well... as I said, the lamps are shining downwards and the floor isn't very bright so I guess there's not much light bouncing off... how should the ceiling become brighter?

...and I just realized your object is something like 11 × 22 kilometers large. I guess you need to crank up the strength of the lamps a lot to light such a vast area. Maybe you should scale everything down to more real-life dimensions...

I packed it with the images and updated the link again. @Chris

@moonboots I renewed the link and packaged it as a visual

Of all the underground garages I've seen after googling a bit, none of their lights had little flaps on the side. Remove them and you should improve the ceiling lighting

there are a lot of ways, to make it lighter. Gorgious already proposed one in the comments.
You can e.g. crank up the exposure in render properties/film/exposure to 5

or use the exposure node in the compositor:

or assign an emission shader via "assign" to your light bulbs.
But of course this changes the way the result will look like. And i don't know whether you want that.

It solved my film/exposure problem and I added an extra area light to all lamps, making it even more original.


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2.8 - Non Linear Animation Editor - How to remove tracks?
I was wondering, how can I get rid of unwanted/unnecessary tracks in the NLA Editor? (i.e. [Action Stash] & [Action Stash].001)
Rightclick -> Remove Empty Animation Data does not do the trick.
Thanks!

you're probably talking about tracks, not strip, X seems to work

I fixed/edited it for future reference.. Thanks, and yes I meant tracks. X does indeed work! I could swear I tried it but nothing happens. Thanks!

Put your mouse on the track name and press X


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How can I assign a different image texture per particle?
I am currently working on making a realistic grass shader in blender, but there's one thing I'm stuck on. I made a few different variations of textures in substance designer to make some of the grass blades look dead or discolored. I split the grass up into multiple particle effects each with a different texture, and while it looks okay, it's too inefficient for me since I already use multiple particle effects each with different object counts and size/rotation settings, so it becomes noticeable that each texture variant is applied to a different particle layer. You can see what I mean here:

I have never found any resource online that can show me how assign a different texture based on particle index, so I spent some time messing around and got this as my node setup. I divided by 15000 (number of particles in my test layer) to get a value from 0-1, then rounded it to a whole number.

...And to my surprise it works! But not really. You can see in my test render (I used a solid red and blue texture so I can visualize it better) that the texture variation is split down the middle of my render. I did not know this how particle index works.

So basically what I'm getting at is I need to know either: how can I randomize particle index distribution, or is there a better way altogether to do this? I should also mention that in my particle settings under "Emission" I have the "Random" box ticked.

There are no issues for me: https://i.sstatic.net/pTpwY.png. Your problem is probably somewhere else. Could you simplify it and share the .blend?

I agree with @JaroslavJerrynoNovotny: works fine for me also with a simple plane. Could you spend a few words about yout particle generation setup? Are you using an array modifier to replicate the emission surface? Does the problem persist even if you use the "Random" output in the "Object Info" node instead of yours math nodes?

@JaroslavJerrynoNovotny I edited my original post to include the .blend

@Carlo Thank you!! I never thought of using the object info node in this case. It was giving me mostly a mix of both colors so I plugged it into my round math node and now it works perfectly. Thanks again.

You can make a color ramp, it's color and not texture, but you can take an object info node, put the random into a color ramp, and the color of the ramp into the color of diffuse node. So it will take a color in the ramp randomly. I hope it will help you.


text:
Why does the camera not follow the object when I'm editing the animation and when I move a line?
I'm new at animating keyframes. The problem I have is that, when I move a line in keyframe to make it slower/fast, the object in that line goes outside of the camera and then comes back to the camera... I'm following a tutorial for this animation but it didn't explain this deep in keyframing.
Here's a clip of the animation to see the problem.
Here are the keyframes of the camera before I shift the line. In this case the plane and the camera are at the same speed all over the animation.

Now I shift the line, and the plane goes faster than the camera for a short time and then comes back in the camera view.

Hello and welcome. While files, images, and external videos or links may be helpful additions they should not be the only way to obtain information about your issue. Don't make understanding your question rely on downloading a file, watching a video or visiting an external site. Use the builtin tools to upload images or gifs, along with thoroughly explaining the problem in written form so it can be indexed and searched for thus helping future visitors with similar issues.

Before you move the keyframes line, camera and plane are at the same speed.
By moving the line for the camera, you do so the camera position associated with these keyframes is reached later.
So for this period, the camera is slower and the plane (unchanged keyframes) is at the same speed but will be faster than the camera for this period.
But, as the next keyframe line is unchanged, the position associated to it will be reached at the same time for both plane and camera.
So for this period, the camera is faster than the plane.
After that, as next keyframes are unchanged, both are still at the same speed.

To say it another way:
Keyframes are defining position, rotation, etc.
Keyframes positions and intervals between keyframes will drive the speed.

sorry, i dint understand very well..


text:
All 3D viewport controls not working
Was working with Blender tonight and suddenly all 3d view port controls stopped working. Can not Pan, Zoom or Rotate my view port with my mouse. I can not select objects on screen by clicking, only drag select works to select items in the 3D view port. Number pad controls are not working. (Numb Lock is on).
Tried
-Loading another file.
-Restarting Blender
-Rebooting Computer
-Setting Blender Preferences to factory default.
None of these things worked.
Only 3d view port controls that still work are rotate,zoom,move gizmos in the upper right of the view port. (But I don't want to use those.)
This is Blender 3.0
Edit: Also tried upgrading to 3.0.1 and uninstalling and reinstalling Blender. Viewport is still unresponsive as described above.

I found the solution to my problem. There was a setting in Blender that was turned on but not obvious. I never found what the setting was but, deleting the userpref.blend file and reopening Blender got my controls to work again.
C:\Users\Username\AppData\Roaming\Blender Foundation\Blender\3.0\config\userpref.blend

Had the same problem. The setting that fixed it for me was Auto Depth as found here.
In a nutshell:

Go to Edit > Preferences > Navigation
Make sure Auto Depth is checked

I have no idea how it got unchecked in the first place, but everything magically started working as soon as I checked it.


text:
How to detail my sword texture?
Good day,
Ok, so here is my Claymore model. I put textures on the blade and hilt and I think it looks good but it needs extra details to bring it alive. I followed Blender Guru's anvil series and while those kinds of scratches work really well on an anvil, I feel they need to be a lot subtler on a sword. I am not sure what to add. I mean scratches yes, but what kind of scratches. They can't be very obvious like on the anvil. I also saw many people put rust but what kind of knight would let his sword go rusty?
Here is my sword

But I want it to look more like this.

Please narrow down your question to a specific problem, also keep only one question per post, as as many as necessary. If it pains on multiple locations then you probably have overlapping UVs

Alright, I edited the question but thank you for the answer.

Texturing is the process of telling a story about the object, where it has been and what it encountered, how it was taken care of, etc.
More than just scratches, you need layers of grunge and dirt build up and to wear it away again to show how it was held, where it was kept. If the object was kept in a museum, then you are done. If it was handled and passed along generation to generation, then the second image is headed the right way sort of. I Don't see the scratches and pits that would show where it contacted something in battle, and I don't see the dirt from being rubbed clean and put away.
Technical answer: You can use another texture image slot image that is set to slight bump, and also affects the color mix with multiply so that you can scrub in some dirt, draw in some scratches. I suggest a white image and paint into it with gray and black using some clouds and noise set to rake and random to keep from looking procedural. Because of the white, you may need to invert the bump node direction from that image to the shader.
I second the idea of setting up lighting for the mood and effect - and I also think it a good idea to post the process on blenderartists.org to get multiple views and input on where to go as you continue.

The best way to go from here is to find some images of swords that you can refer to. From what I know, most swords would be kept well polished and mostly scratch free. If you're going a bit more stylized like you would find in a game, then some scratches on the edge from cutting things would be one of the first things to add.
Before you continue texturing though, I would recommend working on your lighting. One of the reasons the second image "pops" a bit more is due to the colored lights. The main light appears to be a warm off-white, and the second light is coming in from the left and adds a bit of blue to certain surfaces. I would suggest looking at some lighting videos or tips online to help you get started there. Lighting can often be what makes or breaks an image.
The final thing to do would be to add variations in the roughness, spectacular, and normal of your material. Once you have your final diffuse texture you can either use the compositor to convert the image to be able to control each aspect, or some other program to generate the maps from the diffuse texture.

Hmm, I thought the sword was finished too but the more I look at it the more unfinished it looks. What I am trying to create is a well-cared sword. I mean, most sword references I saw were either very rusty or very pristine. I'm not sure what a well-cared for sword really looks like and I am not sure how to make those subtle details. An anvil is made to be carelessly abused all day but a sword is different . I keep getting this nagging feeling that my sword is unfinished and looks lifeless. A friend who is an artist told me the same. Do I really need to add more details or is it finished?

That's not really the kind of question for this site. I would suggest heading over to blenderartists.org and posting your pictures and questions there. This site is more for specific questions and answers, where as a form like BA will be much better for getting feedback and advice. My quick suggestion would be to really focus in the lightning. Bad lightning can make a great model look terrible, and great lighting can make a decent model look fantastic.


text:
How do I unwrap a model proportionally?
I have this revolver model that I want to unwrap using a combination of seams and project from view. I use Texture Atlas to combine all the models into one.
The problem with this method is that some faces are unwrapped disproportionately bigger than others, and I want each island to be in proportion so that the texel density is equal across the whole model. I don't want to do this by hand. I think this is a useful skill to know.
How do I do this? Is there an addon that can help me with this?

Average Island Scale
For this task I usually take advantage of the Average Island Scale operator available in the UVs menu. I don't know the math behind it, but the effect is to re-proportionate the uv island to the region extension of the real mesh.
Here's a basic example:

And here's an example with Suzanne UVs. I duplicated the same object, so the UV island are at the beginning overlapping, then I ran the command.


text:
Mapping planets with spherical coordinates
Setup
I've generated a 'planet' using the ANT landscapes add-on. The exact parameters don't really matter, but suffice to say that it's visually a UV sphere mesh with vertices pushed from the center to varying heights. There is a copy of the object that has had all the 'ocean' faces removed.

Intended goal
Project the globe onto some sort of map (the cartography kind). I'd love to have one of the (more) standard map projections, like a Winkel tripel projection or one of the really cool looking ones, like a Dymaxion or a Waterman butterfly, but I'm really just trying to get it to work.

Current approach
After fooling around with modifiers until my eyes hurt, I finally decided to just bash out the following spaghetti code:
import bpy
from math import *
def map_sphere(bpy_obj):
    vert_cnt = len(bpy_obj.data.vertices)
    coord = [0]*vert_cnt*3
    bpy_obj.data.vertices.foreach_get('co',coord)
    for i in range(vert_cnt):
        x,y,z = coord[3*i:3*i+3]
        p = sqrt(x**2 + y**2 + z**2)
        phi = acos(z/p)
        theta = asin(y/(p*sin(phi)))
        coord[3*i:3*i+3] = [phi,theta,p]
    bpy_obj.data.vertices.foreach_set('co',coord)

Basically, flop the vertices into spherical coordinates and map the spherical coordinates back into the object according to ($\phi$->x, $\theta$->y, $\rho$->z). It's pretty simple, but I'm running into a few key issues:

Huge amount of distortion around the poles
Weird scaling factors in the X and the Y directions
Points on the poles are unmappable. (solved by deleting them.)

Question

Is this the best way of doing this? I feel like it's far too roundabout and there's probably some obvious solution.
If this is the best way of doing this, then how can I reduce the distortion around the poles and/or are there other easily programmable mapping schemes besides equirectangular?

Additional troubleshooting done since posting
I took a simple UV sphere and applied the program to it. The end result was a mesh with two layers literally in the same place. Perhaps I should simply cut my mesh in half and operate on each half separately?

well I would say create your UVs like you want them to look,
then bake the texture using  an equilateral environnement texture plugged in an emit shader with object as coordinate (assuming object pivot point is at the center)


text:
How would I make a Object move while being NORMAL to a surface (Constraints)
I added shrinkwrap constraint to an yellow sphere which is a Child to an empty object, with an arrow constrained to it, as a child object. The empty object follows along a sinusoidal circular-curve.

Here is an file for you to demonstrate this with.
https://drive.google.com/file/d/1LFY7B84YFaYMNpntVDsAWe4lqTM3_Msh/view?usp=sharing

Well I give up this was as close as I could come to making it work... :( Blend file if you want to tinker with it:
https://drive.google.com/file/d/1LFY7B84YFaYMNpntVDsAWe4lqTM3_Msh/view?usp=sharing My test render of my last attempt to make this work

If you want the object to cling to the surface of an object and rotate to be in line with that object's normals, give it a shrinkwrap constraint with "Align to normal" enabled, with the proper axis you want aligned to the normal:

If we want the object to acquire only rotation based on the nearest normal, without changing its position, we can sandwich in a parent that gets the proper location, give it a new child that shrinkwraps, then have our original empty copy world space rotation from that new child:

Um I am not sure if I understood the answer but i tried enabling the shrinkwap option Align to Normal and it is all glicthy now Here is the link to a new file: https://drive.google.com/file/d/1LFY7B84YFaYMNpntVDsAWe4lqTM3_Msh/view?usp=sharing

I don't believe you linked the right file.  There's no object with a shrinkwrap constraint in that file.

the yellow sphere has one also play the animation too to see how it goes wrong, the arrow is supposed to normal to the surface

Oh, pardon, I see it.  First, don't use project, which will move it differently.  Use nearest surface point, the default, and what's in the pic.  Second, look at the spheres' axes.  If you are expecting the arrow to also point in the direction of the curve's normals, it won't, because the arrow is not aligned with the sphere's Z axis-- the axis you're aligning with the normal.  Keep in mind also that you are shrinkwrapping to nearest surface, and if you want that to be the top, keep the constrained object well on that side of the object.


text:
Face orientation
I got a relatively high poly model with faces that aren't in the right orientation. Is there any way to flip all wrong orientated faces but selecting them manually?
After question edit:
I turned down the polys now and merging didn't work either. The model is a letter and currently only a surface, but i want to put a solidify mod on it.  I subdivided the surface before for higher res, and now the polys look in the wrong direction which shows when applying the solidifier.

as Crantisz said - pls write all you have tried before so we don't waste our times with answers you already now. So click on "Edit" and improve your question

If recalculating normals outside doesn't work, you likely have duplicate or non-manifold faces. Try selecting all then press M (merge), and select "by distance". This will get rid of any dupes - you may or may not need to recalculate normals again afterwards. If that doesn't work, as others have mentioned, it would be helpful if you could post some specifics about your project, (ideally) along with some screenshots, so we can help you diagnose the problem better.

Select all → Shift+N This will automatically recalculates normals outside.

I tried that already but it doesn't work...

How it supposed we should know that you have already tried this? Please, elaborate your question and add a screenshot of file, so we could understand why this doesn't work


text:
Is there a way to rotate reflections of the mirrors in clockwise or anti clockwise by manipulating how the mirror reflect?
Right now, I have made two mirrors facing each others and a tunnel in the middle (like in viewport at the bottom-left corner of the pic). So the reflections will bounce back and forth as many times as glossy bounce limit, making it seems the tunnel goes way longer than it actually is.

What I want to achieve is to make the reflections rotate/twist a certain amount every time it reflect from a mirror. So it would seems like tunnel goes in spiral.Also, the spiral effect will hide some repetitions from reflections. I'm wondering if there's a way to achieve this by manipulating normals on the mirrors.
The goal is to make a scene looking up from inside of a tornado. The walls will be converted to volumes and displaced to make it seems like clouds and twist it to make it spiral up.
In real world, such effect can be mimicked by having a lot of grooves that radiate from the center of the mirror. In each groove, the surface is tilted a few degrees. I'm trying to make a abstract scene that will look like insides of a tornado. The wall of the tunnel will be displaced or made volume. I'm trying not to use too many geometries by using mirrors and make it less repetitive by making it look like a spiral.
[edit]Here in this screenshot is how the exact effect is achieved by modelling the geometry of the mirrors. In the picture, cylinder is a normal cylinder but it spiral out because of reflections. How can this be done just by manipulating normals?

There is no real world scenario with this working, is there? What objects are reflected there? Where does the light come from? What do you want to show with this render?

@MartynasŽiemys In real world, such effect can be mimicked by having a lot of grooves that radiate from the center of the mirror. In each groove, the surface is tilted a few degrees. I'm trying to make a abstract scene that will look like insides of a tornado. The wall of the tunnel will be displaced or made volume. I'm trying not to use too many geometries by using mirrors and make it less repetitive by making it look like a spiral.

Hello, Pyae, welcome..  .. your question would be more self-contained and clearer, if you edited a version of your comment into the post.

@Pyae OK, that makes it a bit clearer, however you still skipped the most essential part - what would be reflected in the mirror and what the image should show. You also need a light source. If it can be done with grooves, you can make them with geometry or by manipulating normals - bump or normal map.

Thanks @RobinBetts, I've added more information to my post.

@MartynasŽiemys Yes, as now, I've added some point lights in the tunnel. The two mirrors will be reflecting each other and the cylinder(clouds) between them. Like here https://imgur.com/a/iYwhZjZ. In this pic, the clouds are reflected 2-3 times and there's a dark end as the reflections stopped because of glossy bounce limit (I'll be using much higher limit in final pic ofc)
I'm trying to figure out how to make reflections rotate and go spiral alltogether by manipulating normals of mirrors. But unlike real world, I think it can be achieved just by manipulating normals, without needing grooves.

I was curious about doing this with a refraction mesh, rather than with the normals of a mirror, and I believe this may be what you're after:

I'm doing some weird things in this "mirror tunnel".  The selected mesh is a refraction mesh with impossible normals, rotated based on their polar coordinates.
Realistic lenses have backfaces that kind of undo the refraction when the rays leave the lens, but this doesn't, which means that you get successive refraction with each bounce through the tunnel.
If something like this is what you're after, there's plenty of room for playing around with it.
Looks like you can do something similar by giving one of your mirror caps these same impossible normals:

Don't want both of the mirrors to have the same material though.  One of the caps should just be a regular, flat mirror.  Not entirely sure why.

Yeah, this is definitely what I'm looking for. Achieving it through nodes give so much control over the effect. Thanks. I'll also try similar nodes like yours on normals too.


text:
How to create unsigned Int property?
I need a property that can accept the 2267538950 number, unfortunately by default Blender uses a signed int range. There was a way to set subtype="UNSIGNED" in the previous versions but it doesn't work anymore(?) and I get an error
value not in 'int' range ((-2147483647 - 1), 2147483647)
bpy.types.Scene.vertInt1 = IntProperty(
 name="Integer",
 description="Enter an integer",
 default = 2,
 subtype='UNSIGNED')

Python int can accept any size limited by memory as far as I know, so int in [-inf, inf] in documentation for maximum value (https://docs.blender.org/api/current/bpy.types.IntProperty.html) seems to make sense. I would report this as a bug or ask on devtalk forums. At least the documentation is wrong... In any case why do you need this?

I import values from a mesh format that uses uint for certain values and would be great to import them as is without an extra step with conversion them to something else just for blender

Okay I found it kinda works if you do it as simple code, but in the property group class where I need it, it raises this error

It did not work in any IntProperty I tested it on...

I handle this by converting to a string.

authors: Ігор Спасівський


text:
antialiasing is disabled when using Compositing nodes?
I just added a simple compositing node setup to add glare to my scene.
The edges of my cubical objects seem very jagged when enabling nodes while rendering.
I think it might be an antialiasing issue.
I've tried the "Full Sample" mode, but I see no difference.
What's going on?

Please provide some screenshots to estimate issue.

Are you using the Z-buffer or the Object ID buffer in some way? These inputs are normally not anti-aliased.


text:
How to toggle to camera view via python?
Is there a way to programmatically achieve the same thing as pressing the 0 key the numpad?

are you looking for the operator ?

if it is a bpy.ops thing that's fine, but I already "own" the camera and if I could assign it to a "view-slot" or something that would be awesome..

do you want to set which camera is used for this view ?, the 3d view can have it's own active camera without affecting thescene camera

What do you mean by "view slot"? Do you want to bind the camera to another key?

@poor nvm the phrase "view slot", I'm looking for a way to achieve what the first answer is about, but without swicthing the area-type

The operator for switching the 3D view which is associated with numpad keys is view3d.viewnumpad().  You have to be in the right context (3d_view) to use it and select which view you want to set:
import bpy

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        override = bpy.context.copy()
        override['area'] = area
        bpy.ops.view3d.viewnumpad(override, type = 'CAMERA')
        break

Another way, without the operator would be:
import bpy

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        area.spaces[0].region_3d.view_perspective = 'CAMERA'
        break

Which is equivalent to:
import bpy

area = next(area for area in bpy.context.screen.areas if area.type == 'VIEW_3D')
area.spaces[0].region_3d.view_perspective = 'CAMERA'

Other options are  [‘PERSP’, ‘ORTHO’, ‘CAMERA’]

that is working if the area type is 'VIEW_3D', but is there another way, to achieve this thing without temporarily switch the area?

the context should be VIEW_3D , but you can do it without switching, I will edit

just to be sure: there is no other way, then using the bpy.ops, right? (btw switching back and forth is way shorter than the solution you have provided after the edit -- but I have no idea, what is the advantage of you way vs. the "switching" way)

the best way is to put it into a function (e.g in the main of the template: simple operator)
def main(context):

    if context.region_data.view_perspective in  {'PERSP','ORTHO'}:
        context.region_data.view_perspective = 'CAMERA'
    else:
        context.region_data.view_perspective = 'PERSP'
    return {'FINISHED'}

notice region_data
another example to not do a loop over areas...
def execute(self, context):
    context.space_data.overlay.show_extra_indices^= True

to switch show_extra_indices (edit mode)
show_extra_indices


text:
Multiple materials in BGE
I have an object with a single mesh, and it has a subdivision surface modifier on it. I'm using BGE, and I cannot figure out, how to render both the wireframe (let's say in white) and the faces (let's say in red) of this object at the same time.

is it okay if you duplicate the mesh and assign one of them to a material with wire render ?

@Chebhou unfortunately not, because the vertices of the mesh will be modified on-the-fly, and I don't want to modify the two at the same time with the same amount, that is just an unnecessary overhead...

http://blender.stackexchange.com/questions/6361/how-can-i-make-an-object-render-with-a-wireframe-in-the-game-engine maybe this isn't exactly what you need, but it sounds good! You can just use an overlay texture on it with alpha transparency that you gather from unwrapp!


text:
AttributeError: '_RestrictData' object has no attribute 'filepath'
I'm working on a small post-save-hook, which is working pretty nicely only if the file is saved first and then the script is loaded later on. If I install my addon from the file and I save the currently opened new blender project I have this error:
AttributeError: '_RestrictData' object has no attribute 'filepath'

Which comes from the line, where I try to access the filepath data of my blender file:
path = bpy.data.filepath

When I remove my script, save the blender file and then readd my script it works again. So basically my question is:
What is the workaround of this issue? Can an already loaded module reload itself? Or is there some other way to do this properly?
Thanks in advance!

This is a side effect of the way you import.
from bpy import data as bpy_data imports the bpy_struct data when the py file is loaded, like a local copy (not alias). This happens during the addon registration, thus bpy_data will be and remain as:
<class 'bpy_restrict_state._RestrictData'>

In contrast, import bpy and a later use of bpy.data accesses data in the moment you actually use it. It is _RestrictData at registration time, but later on it will be
<class 'bpy.types.BlendData'>

You should change your imports from
from bpy import ( data as bpy_data,
                  context as bpy_context )
from bpy.app.handlers import ( persistent as bpy_app_handlers_persistent,
                               save_post as bpy_app_handlers_save_post )
# ...

to
import bpy
from bpy.app.handlers import persistent

# ...

@persistent
def foobar(scene):
    bpy.data.filepath
    #bpy.context...

# ...

bpy.app.handlers.save_post.append(foobar)

from ... import ... as ... should only be used if the imported module or function would overwrite another.

That was exactly the problem. Doing the from .. import .. as .. was a micro optimisation -- as it is working quite well for python modules, reduces the number of look ups as it is adding the exact value to the global name space. Thanks!

To make this work in an addon, add the foobar function to __init__.py and add the bpy.app.handlers.save_post.append(foobar) line to the def register() function

The _RestrictData object indicates that you were trying to access stuff in bpy.data.(...) before ( blender is ready )
I don't know the technical details but I know that it happens during startup if you access bpy.data prior to register()
The first time blender reads the script is just to gather bl_info and make sure that register() is defined in the script.
After this reading of the file, blender may have other scripts to scan and so it moves on to scan the rest of the files in addons/startup...
Then, after that, if the addon is to be enabled, blender calls the script's register() ––> and from there it is usually safe to go for bpy.data.(...) or bpy.context.(...)

The line I'm referring to is inside the function which will be registered by blender itself. In my module level there is only 4 functions, two of them is the register and unregister, a dictionary, which is the bl_info and the call of the register. So I guess this shouldn't be the problem..

You're not allowed to access bpy.context and bpy.data at registration time, so not in the register() function, nor in any function that is called in inside the register() function. It typically happens 'cause one tries to give a custom property a default value - e.g. bpy.types.Scene.prop = bpy.props.StringProperty(default=bpy.context.scene.name)

@CoDEmanX probably I wasn't clear enough: I don't call/use any of the bpy.data nor the bpy.context in the register function. I use them in the function I register with the register function == the feature itself

Please post the exact code. If you access bpy.data directly in the class scope of a class you register (and not in one of its methods), then it's the same story - it is executed immediately on registration / loading.

@CoDEmanX thanks for helping, here is the code. Oh, and the problem is in line 102.


text:
Is there a list of all nodes in blender?
How do I get started working with nodes and is there a complete list of nodes so I can view them?

Here's a great list of geo nodes, maintained by Quellenform: Can't find the node! Which node is available in which Blender version?

Yes there is. However the list is much too long for an answer here. I have included a list of all the node types. There are many more nodes under each type classification. Click on the type you want to learn about. Or click the title for the section to view the index on the wiki.
Compositor Node Types:

Inputs
Outputs
Color
Vector
Filters
Converters
Mattes
Distortion
Groups
Layouts

Material Node Types:

Input
Output
Color
Vector
Convertors
Groups
Open Shading Language
Shader
Texture

Geometry Node Types
[from editor: since it changes a lot currently, I recommend this list maintained by Quellenform: Can't find the node! Which node is available in which Blender version?]

As for getting used to working with them, explore and experiment! You will stumble across all sorts of goodies. You can also try an online shading tutorial. Once you get better with nodes, I would suggest you try reaching a specific result, i.e. a Wood material, a Galvanized Steel material, etc.

The above links went stale. Not surprising given how much has happened in the years since original posting. The wiki seems to have pretty good lists. Here is a start:
Shader Nodes
Compositing Nodes
Geometry Nodes


text:
BGE. How do I make the plane stop the ball
I am a first-time user of the BGE and I am trying to follow a tutorial on the BGE with a ball and a plane, but after following the instructions so far, the ball goes straight through the plane. How do I make the plane stop the ball from falling?

First, set the ball to dynamic or rigid in the properties toolbar under the physics tab. Then set the plane's physics tab to static if you want it to remain still.
If the ball still goes through. In the same physics bar tick "collision bounds" and put respective collision bounds to each item. I guess box to the plane and sphere to the ball.

That's what I did and the ball still goes through the plane.

Share your blend file through here and post the link after : http://www.pasteall.org/blend/

I tried it in another version of Blender and it worked. Thanks anyway.


text:
how can I open an hdr in blender
I have tried to see where I can open the hdr files but could not find anywhere.
I want to open and view the 360 degrees hdr in blender. How does one accomplish this?

Are you trying to open the image in the image editor or to see it spherically projected in the background of your scene?

@Duarte Is your version 2.78, that's what I'm using and I dont have the same view as your illustration. Thanks again.

I mean I don't have "surface" under "custom properties".

How do I know that @Duarte will look at this again? I have no way of contacting him! Nothing for that even on his profile.

Sorry @Duarte, I forgot the Cycles renderer! And thank you, I did it!

Blender is not an image viewer application, you can't just use Blender to directly open image files from File > Open
You also can't just "view" images directly nor can you expect it to just open a spherical image as display it as a panorama viewer.
You can however use the builtin UV Image Editor to view regular images and use a workaround to view spherical 360 panoramas.
Starting a few versions ago Blender added support for world preview as viewport background. As a workaround you can use that as sort of a spherical image viewer. It will be obscured by the 3D View interface (grids, cursor and objects), but serves as a basic viewer.
With Cycles as your current render engine create a new World datablock from the Properties Window. Add a new Environment texture to its color input.
Pick the Open image button and browse your file system to the desired image file (JPG, PNG, or HDR formats).
Pick the image then in the Properties Shelf over the 3D View (N key) under View tab activate the World Background option if disabled.
You should now be able to use the 3D Viewport as a basic spherical 360 panorama viewer.

To disable grid, cursor, empties etc from showing enable Only Render option in the same Display scroll. It will disable any (including mesh) objects as well if they are set as non-renderable.


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How can I render an object with an hdr background?
I have an object with an hdr for the background. What do I do in Cycles to render the background with my object?
How is this different from an ordinary render in Cycles?
The hdr is a big one, 350MB.

Thank you @Cegaton, I didnt make my self clear! Sorry. I already have that part, it is the rendering that I dont know. I have an hdr in blender and an object that I have made.


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All my windows and UI disappeared

How do I fix this? I need to see the entire UI.

There's generally a couple buttons at the top that toggle some of the UI

You may have accidentally pressed Ctrl + Spacebar
That keyboard shortcut toggles the maximization of the area. See https://docs.blender.org/manual/en/latest/interface/keymap/blender_default.html
Press that keyboard combination again to toggle it off.

If all else fails, you can save your .blend file, close Blender, relaunch it, and do File > Open, but this time opt not to load the UI.
The .blend will load with the interface remaining as you have it in your startup file.

Above: Untick the "Load UI" checkbox.
This is in the file browser on the right panel. If you don't see that panel at first, press N to expand it.

I found that Ctrl + Alt + Spacebar does the same thing as Ctrl + Spacebar: Toggle Maximize Area.
But! If you used Ctrl + Alt + Spacebar to Toggle Maximize Area, you have to use Ctrl + Alt + Spacebar to toggle it back. That is, Ctrl + Spacebar won't do. And viceversa.
Note: Alt Gr + Spacebar is the same thing as Ctrl + Alt + Spacebar.
I accidentally pressed Alt Gr + Spacebar (On Blender 3.6, Windows 10), searched online, found about Ctrl + Spacebar in this page, and it didn't help me. I tried Ctrl + Alt + Spacebar thinking it could have been a keyboard issue, and that worked. On Blender 4.3 it works the same way, I tried before posting this answer.


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Whenever I try joining two objects, it combines the modifiers too
I have one object that has the “screw” modifier. When I join it to another object it gives that object the screw modifier too. I even tried with the Boolean modifier, but it doesn’t let me move both objects at the same time.

If moving the objects together is the only concern, try parenting them by using Object (Keep Transform) option in the parenting context menu that you can open with Ctrl+p. You select child object first and then the parent object. You can delete this parent-child relationship by opening Clear Parent menu by pressing Alt+p and selecting Clear Parent option.


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Make helix bent into a circle have same thickness everywhere

Here is the ring I made. I bent (simple deform modifier) a helix by 360 degrees. The helix works right and is the same thickness everywhere, but this is not also true for the bent ring.
I tried to use different methods such spinning it with another spline, but I get the same result every time.

please provide blend file

https://we.tl/t-FIcfVqSG58

wetransfer link - this is the .blend file above

i am pretty sure it can be done via geometry nodes. unfortunately i am too dumb to make it...i can make it with a simple circle:  [1]: https://i.sstatic.net/bRwcN.jpg. but i cannot get the right rotation for a spiral...but i am sure Robin can do it ;)

You could create a segment with a Screw modifier, then create an empty:

Give your object an Array modifier with the empty as Object Offset, move and rotate the empty untill it makes a complete circle:

Edit the object so that the segments stick to each other:

Niiiiiiice!!!!!!!

Thanks, I hope it answers. I love the Simple Deform modifier but you can't avoid deformation with it, so Array is a solution

i tried to make an answer using curves, and bevels and lost an hour on it. this works much better :D

@Jachym Michal oh yes I didn't try with curve bevel... Edit: Ok but as soon as you bend it 360° you probably have the same problem