text:
Simulating sedimenting cylinders with a particle system and molecular addon
I want to simulate rod-like particles falling slowly down onto a surface. Eventually, my goal is to retrieve the thickness of the 'carpet' formed by those cylinders by this process.
For this, I have downloaded the molecular add_on, and set up a python script to run in the scripting window of blender
import bpy
import math

def cylinder_between(x1, y1, z1, x2, y2, z2, r):

    dx = x2 - x1
    dy = y2 - y1
    dz = z2 - z1
    dist = math.sqrt(dx**2 + dy**2 + dz**2)

    bpy.ops.mesh.primitive_cylinder_add(
        radius = r,
        depth = dist,
        location = (dx/2 + x1, dy/2 + y1, dz/2 + z1)   )

    phi = math.atan2(dy, dx)
    theta = math.acos(dz/dist)

    bpy.context.object.rotation_euler[1] = theta
    bpy.context.object.rotation_euler[2] = phi
    bpy.context.object.name='dacyl'

cylinder_between(0,0,0,1,0,0,0.03)

bpy.ops.mesh.primitive_plane_add(radius=8,location=(0,0,0))
bpy.context.object.name='bouncer'

bpy.ops.object.modifier_add(type='COLLISION')

bpy.ops.mesh.primitive_plane_add(radius=5,location=(0,0,5))
emitter = bpy.context.object

bpy.ops.object.particle_system_add()
psys1 = emitter.particle_systems[-1]
psys1.name = 'Drops'
pset1 = psys1.settings
pset1.name = 'DropSettings'
pset1.render_type = 'OBJECT'
pset1.dupli_object = bpy.data.objects["dacyl"]
pset1.particle_size=1
pset1.drag_factor=0.5
pset1.effector_weights.gravity=0.2
pset1.normal_factor =0
pset1.jitter_factor =0
pset1.frame_end=500
pset1.lifetime=10000
pset1.distribution = 'RAND'
pset1.use_rotations = True
pset1.phase_factor_random
pset1.rotation_mode = 'OB_Z'
pset1.rotation_factor_random = 1

pset1.mol_active = True
pset1.mol_density_active = True
pset1.mol_selfcollision_active = True

Where I have simply defined a cylinder to be the object of a particle system. I want the cylinders to avoid one another and this is why I have used the molecular add-on.
When I turn on the simulating engine of the molecular add-on, my cylinders fly all around the place but do not fall down anymore. Furthermore, they do not seem to intersect properly with the bottom plane which is set to 'collision', but rather only their centers seem to intersect the plane.
Lastly, I fail to see whether the cylinders really collide off of one another.
Could you explain to me what I am doing wrong ?
Regards,
 any feedback appreciated
PS: I am aware the code looks a bit contrived and weird. I am starting with blender python and I took code snippets left and right from the stackexchange/google.


text:
Blender keep rendering multiple png´s even though I only want to render a single frame
I am relatively new to blender.
Even though I have selected the Output Image to PNG (not movie) and pressed the ordinary rendering button (not animation), Blender keeps rendering the whole scene from frame 1 to 150. I am rendering in Blender Render mode.
The scene is a part of a Smoke physics simulation.
Until recently it was working fine.
Suggestions much appreciated.

Thanks for your suggestion, but that's not it.
I am in fact pressing the Camera Icon rendering button and not the animation button. Still blender starts rendering multiple frames, just as if it´s creating a movie. It´s odd. Thanks for the tip regarding F3.

Posting the .blend would be helpful.http://blend-exchange.giantcowfilms.com/

source: Stack Exchange

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

sort: votes


text:
How to get consistent stroke thickness when zooming grease pencil?
I've noticed that when I am using the Grease pencil with a placement other than "view" the thickness stays the same thickness based on the view in a way that it isn't effected by it's perceived distance from the camera.
Is there a way to make the stroke thickness remain consistent with its distance from the camera? And as a side note, is there a way to change the thickness to something larger than 10px?

As for thinkness larger than 10px, you can directlly input the desired number.

@Allosteric the problem is that the thickness is not consistent the the 3D environment, its consistant to the camera so when you zoom the line appears to be getting thinner relative to everything

my answer was just meant for the side note. I myself was curious on the main question (and set the bounty) so I didn't want others to be bothered with >10px lines.

It appears you can get something like this, by enabling "Volumetric Strokes" in your grease pencil palette.

This creates the following effect (reduced opacity for clarity, volumetric is on the right hand side).

The sampled points can be increased by adding subdivision (default is 0 for basic brush) under the stroke quality section in the grease pencil panel. Increased subdivision is only applied to new strokes though.

The volumetric strokes retain their size, regardless of viewport zoom.

Lastly, grease pencil objects are coming to blender 2.80, which will support proper scaling.

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


text:
My blender render view ports are slow in material mode, but I don't know the reason
I am working on a project for a level map for a small lowpoly city. I have 143 materials and I used 111 materials from them, but the problem is that my view port is very slow. The program only uses about 65% of my RAM and less than 50% of the CPU power. All of my textures are 1500px * 1500px  and all of my materials are shadeless. I don't use any lights and I have only 5000 faces on this layer.
What could be the reason? Are the problems from Blender or from my PC? Can I do this task in blender or do I need a different software?

143 materials is a lot. DO they all have image based textures?

@DuarteFarrajotaRamos yes they all have images

Well that is probably the reason, combined with the fact that Blender's viewport is inherently low performance

@DuarteFarrajotaRamos so are there any good software i can use in this task ?

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


text:
How to set the orthographic camera with babylon.js?
I'm struggling with using the orthographic camera. I don't know how to set the

orthoTop
orthoBottom
orthoLeft
orthoRight

Can anyone be so kind to help me understand how to calculate these values? Where do these values come from?
One similar question is here:
http://www.html5gamedevs.com/topic/28449-blender-orthographic-export/


text:
How can I get rid of multiple normals in a face with more than 4 vertices?

Each one of the faces has 20 vertices (I know that every face is actually made out of triangles), but shouldn't it have the same normals? Or maybe there is a way to access those "background virtual faces" and fix it? It also does show up in the render.
I've noticed that it only happens with smooth shading. (Isn't it supposed to make things smoother?) I think it's okay with just flat shading, but I still want to know what's up.
Edge split modifier seems to be a good solution.

Add an Edge Split modifier toyour mesh or turn on Auto Smooth in Object Data tab.

I solved it extruding and addind faces in every key

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


text:
How can I clear the weight from outsiders vertex when weight painting?
I can not fix a problem with a vertex to which I can not eliminate the weight of a certain bone. The worst thing is that I can add weight, but never subtract weight.
Does anyone know how I can fix this?


text:
doubt in rigging
In the image 1: How can I move the "con eye" under "con root" since in Unity I can only select one root bone?

In the second image I can see many con cheeks, con teeth, etc. in the dope sheet, but I couldn't see it in the outliner. Is it hidden? How can I see it?

Hi. Seems like you're asking two separate questions here. Please only ask one question at a time. You are welcome to ask as many questions as you need, but as separate posts.


text:
script addon Blender filepath
I wrote a little script addon but I can't put operator in panel with filepath to export to folder. The example under, I wan't to replace path with panel.
# EXPORTE EN COLLADA -
class ColladaExport(bpy.types.Operator):
    bl_idname = "object.colladaexport"
    bl_label = "Collada export"

    def execute(self, context):
        path = "D:\Documents\VR\mixedRea\polypheme\models"
        selection = bpy.context.selected_editable_objects
        bpy.ops.object.select_all(action='DESELECT')
        for obj in selection:
            if obj.type == 'MESH':
                obj.select = True
                bpy.ops.wm.collada_export(filepath = path + "/" + obj.name,
                                          check_existing = False,
                                          filter_blender = False,
                                          filter_image = False,
                                          filter_movie = False,
                                          filter_python = False,
                                          filter_font = False,
                                          filter_sound = False,
                                          filter_text = False,
                                          filter_btx = False,
                                          filter_collada = True,
                                          filter_folder = True,
                                          filemode = 8,
                                          selected = True,
                                          active_uv_only = True)
                obj.select = False

        for obj in selection:
            obj.select = True
        return {'FINISHED'}

Thank you
Thank you very much for these indications. I'm going fast with an ant ... I followed your directions. The good text is written correctly with the brother button But the recording in collada in the chosen file does not work. Here is the script:
import bpy
import os

from bpy.props import StringProperty, BoolProperty, EnumProperty
from bpy.types import Operator

class ColladaExport(bpy.types.Operator):
    bl_idname = "object.colladaexport"
    bl_label = "Export collada"
    filter_folder = BoolProperty(default=True) # only folders
    directory = StringProperty(subtype='DIR_PATH')

    def execute(self, context):
        selection = [o for o in context.selected_objects if o.type == 'MESH']
        scene = context.scene
        for ob in context.selected_objects:
            ob.select = False

        for obj in selection:

            scene.objects.active = obj
            obj.select = True
            filepath = os.path.join(self.directory, "%s.dae" % obj.name)

            bpy.ops.wm.collada_export(filepath=filepath, check_existing=False, filter_blender=False, filter_image=False, filter_movie=False, filter_python=False, filter_font=False, filter_sound=False, filter_text=False, filter_btx=False, filter_collada=True, filter_folder=True, filemode=8, selected=True, active_uv_only=True)

            print("collada export", filepath)
            obj.select = False

        for obj in selection:
            obj.select = True
        return {'FINISHED'}

class VrTools(bpy.types.Panel):
    bl_category = "Tools"
    bl_context = "objectmode"
    bl_label = "VR Tools"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'TOOLS'

    def draw(self, context):
        layout = self.layout
        self.layout.prop(context.scene, "directory")
        op = self.layout.operator("object.colladaexport")
        op.directory = context.scene.directory

def register():
    bpy.utils.register_class(ColladaExport)
    bpy.utils.register_class(VrTools)

def unregister():
    bpy.utils.unregister_class(ColladaExport)
    bpy.utils.register_class(VrTools)

if __name__ == "__main__":
    register()

You need to create a StringProperty to hold your path, then to access it in panel with layout.prop(...).

Don't use backslashes for file paths, or escape them properly. Use either r"D:\Documents\VR\mixedRea\polypheme\models", "D:\\Documents\\VR\mixedRea\\polypheme\\models", or "D:/Documents/VR\mixedRea/polypheme/models"

Invoke the filebrowser
If the filebrowser is invoked with only a directory property and no filepath it will only have choice of folder to export to.  Possibly more handy than having a path to set in the UI.
To call the operator from code with a directory use bpy.ops.object.colladaexport(directory="/tmp") and it wont invoke the filebrowser.
import bpy
import os

from bpy.props import StringProperty, BoolProperty, EnumProperty
from bpy.types import Operator

class ColladaExport(bpy.types.Operator):
    bl_idname = "object.colladaexport"
    bl_label = "Multi Collada export"
    filter_folder = BoolProperty(default=True) # only folders
    directory = StringProperty(subtype='DIR_PATH')

    def execute(self, context):

        selection = [o for o in context.selected_objects if o.type == 'MESH']
        scene = context.scene
        for ob in context.selected_objects:
            ob.select = False

        for obj in selection:
            scene.objects.active = obj
            obj.select = True
            filepath = os.path.join(self.directory, "%s.dae" % obj.name)
            '''
            bpy.ops.export_scene.collada(
                    filepath=filepath,
                    use_selection=True,
                    )
            '''
            print("collada export", filepath)
            obj.select = False

        for obj in selection:
            obj.select = True
        return {'FINISHED'}

    def invoke(self, context, event):
        wm = context.window_manager
        wm.fileselect_add(self)
        return {'RUNNING_MODAL'}

# Only needed if you want to add into a dynamic menu
def menu_func_export(self, context):
    self.layout.operator(ColladaExport.bl_idname, text="Text Export Operator")

def register():
    bpy.utils.register_class(ColladaExport)
    bpy.types.INFO_MT_file_export.append(menu_func_export)

def unregister():
    bpy.utils.unregister_class(ColladaExport)
    bpy.types.INFO_MT_file_export.remove(menu_func_export)

if __name__ == "__main__":
    register()

    # test call
    bpy.ops.object.colladaexport('INVOKE_DEFAULT')

Note: just found out the collada exporter I have doesn't work, so I commented it out
As a stand alone property
If you wish to define a directory on say the scene object, use the 'DIR_PATH' sub-type of a StringProperty
bpy.types.Scene.directory = StringProperty(subtype='DIR_PATH`)

can display in a draw method via
self.layout.prop(context.scene, "directory")

which will include a browse button in layout to set folder using filebrowser, like that shown for setting the render output folder.

and can use this setting in operator above from draw method with
op = self.layout.operator("object.colladaexport")
op.directory = context.scene.directory

in which case could remove the invoke method in operator above to not invoke the file browser.
Since you are using if for an addon, saving to the addons user preferences would be a good option.  See this answer
EDIT  given the edit to your question, you need to register the scene property.
def register():
    bpy.utils.register_class(ColladaExport)
    bpy.utils.register_class(VrTools)
    bpy.types.Scene.directory = StringProperty(subtype='DIR_PATH')

def unregister():
    bpy.utils.unregister_class(ColladaExport)
    bpy.utils.register_class(VrTools)
    del(bpy.types.Scene.directory)

Thank you very much. I understood a number of things thanks to you. But in fact I did not speak well (my English is not good). To be honest, this is an addon to help put 3D models in VR with A-Frame. Here is the whole code of my addon. I wish I could enter the destination folder of my selection in a text box and I sadly fails on this detail. Thank you so much.

You forgot to paste the link?

320/5000
Thanks thanks. I did everything right. it's very nice, but it does not save the collada file in the destination folder I chose. I think it's the "filepath" that is not recognized .. I give up. I will manually enter the destination file each time. Thank you for this valuable information. See my sad failure on the blend file:                                             https://www.olborne.com/telechargement/exportCollada.blend


text:
I can only see model via a transparent grey strip
I can only see the model via that strip

Render view


text:
After UV unwrapping > Shading > Add image Texture > Object show no image texture
Blender 2.93.6/Windows 10
I am following a demo. I added a material brown color to my landscape which is showing fine. Then I selected my object and UV > Unwrap. Then change to shading > Add texture Image. The Texture image is not showing in either Material Preview or Render. It does show the brown color though.
I tried :
Using Unwrap and Project from view  > Same result
Changing Render from Eevee to Cycles to Workbench > Same result.

Here is the UV Editing view

Any help is greatly appreciated
(Happy New Year!!)

Beginners issue. I had the "Use Nodes" disabled. Thanks!

plug in a mapping node and a coordinates node set to UV. make sure your texture scale is not to large or to small in de mapping node.


text:
Display issue in UV mode. Likely zoom is kind of stuck. How to reset view/zoom?
Another beginners question. I have been working on a landscape I then moved to UV Editing and now I cannot properly see my object. I had used it for this project before and it was working. My landscape had already texture applied to it but to edit it, I had disabled it. The object is now plain brown color.
It seems as if the Zoom was too close but when I tried to move the zoom out it does not go out enough. I see only brown. Pressing Keypad 7, and the screen is showing nothing (all grey) , Keypad-0 shows all brown like very close. It is the same if working in Object, Edit mode, Weight paint. When I click on the magnifying glass icon and try to zoom out or in, it does not work.

Additional info: The size of the landscape plane is 200m x 200m. When going to UV Editing . The right side window with the object shows "Kilometers". I tried the numpad . but still does not  show the object. I tried numpad + or numpad - and no changes.

Thanks for the feedback. I am still unclear what was the issue. I skipped that project and started a new one.
I tried selecting and using the numpad "." I also tried View Align View with some partial success. At then end my Zoom in layout mode while on camera view was also off which lead me to the speed of zoom in camera view mode. I tried adjusting it but it was really stuck like if it were at an extremely short distance but unable to move forward or backward. I will try to get back to it once I get more familiar with blender


text:
How to optimize Blender - Settings?
So, I upgraded my computer and now it is working much better. Still, I wonder if there is any document that explain how to best optimize it to match the computer.
For example, I was working on a sculpting with an image with about 9M faces. The system started to crawl at times, so I monitored my system capacity and,

GPU not very utilized with a top of about 27% usage.
CPU very lightly used (12700K)
Ram, still plenty available. 32GB Ram total, 70% top used
Using M2 SSD for scratch disk. Also seems low used.

I am trying to understand if the system was ok in capacity what is causing blender to slow down heavily at times.
I am not yet at rendering. Working sculpting on viewport shading.
Blender 3.21
Windows 11
Prefernces > System > OptiX (as using RTX GPU)
Thanks

Blender keeps several "copies" of your file on hand for the purposes of "undo" steps - the amount (default 32) can be changed under Preferences > System. Lowering the number may make things like sculpting more responsive, but this does affect how many times undo (Ctrl+Z) can be used so don't go too low.

You can hide parts of your scene/object that you are not working with at that moment by using collections, local view(/) or Alt+b in "Solid" viewport shading mode.
Also some operations in Blender might be done with only one CPU core, so it may(or may not) speed things up while modelling or sculpting if you disable Intel's Hyperthreading(in UEFI), but that will slow down rendering a bit. You may want to test if it makes a difference and if you care about it.
Generally this kind of optimizing should not matter. Working smart and not having unnecessary mess in your scenes and models is usually way more useful than trying to optimize hardware or software performance as it may improve speed of your work a couple of times as opposed to a couple of percent.
Other than that, there are no specific steps you should really take to optimize your PC for Blender or Blender for your PC. Modern operating systems take care of everything well. You might want not to run too many apps and programs in the background, scan your PC for viruses and malware from time to time.


text:
How can I add inputs to a file output node?
New to Blender. How to add additional inputs to the file output node?
This post doesn't explain:
How can I render all render passes to files in Cycles?

Welcome to the site :) I've edited your question a little to try and make it more concise. If you disagree with my edits, feel free to rollback or [edit] them

related: http://blender.stackexchange.com/questions/16152/save-all-render-passes-to-a-single-exr-image/18406#18406

Click the Add Input button in the properties panel (N) when the file output node is selected:

Thanks, i didn't have the properties panel open. The interface still confuses me :)


text:
Modeling a 3 Blade Boat Propeller
I  am trying to model a 3 blade boat propeller,  like the one shown in the image.  The image was taken from : http://sdshobbyusa.net

I wasn't able to come up with a good way to model this propeller.  Does anyone know a good technique for modelling this hard surface model with good topology ?
Thank You!

I believe I have gotten the result that I desire. I still need to work on it a little to make it even better.  I did it because of PGmath 's help  (https://blender.stackexchange.com/users/5705/pgmath) . Thank You!

and

Model the blades straight and then use a simple deform modifier set to twist.  I am working on an answer now.

@PGmath You are denying speed answers like my a shot at this by calling out the method in the comments! D:

@PGmath I found that adding two simple deform modifiers, one for twist and one for bend, produced an OK result, but still not what I want. I am still unable to come up with a solution.

You could also try the extra objects addon, add a "Worm" and play with the settings.

@GiantCowFilms  Sorry, that's not what I intended to do.  I also didn't expect to take this long, it took me a while to get the topology of the fin good enough for deformation. :)

Here's how I would create a propeller like the one pictured.
First create a cylinder and extrude 3 of the faces out and model them into a propeller blade shape.  To get decent topology you can extrude along the edge of the blade and then use Grid Fill to fill it in.

Then just add a Simple Deform modifier and set it to Twist, I used an angle of 90°.

Note: in the above example, instead of modeling all three fins at once, I deleted a third of the cylinder and used an Array modifier with the pivot point set to an empty rotated 120°.  That way I only had to model one blade.


text:
How to get an object to spawn at a specific location?
How would one spawn an object at a specific location?
Let's say I wanted this object to spawn in behind another object once the distance was less than 2 blender units.
So the object I want to spawn in behind another object can also be defined as "nearest" (nearest = object)
therefore
nearest.worldPosition.x = (?)

Can someone point arrows towards where/what worldPosition would be? Especially if the location of the object I want it to spawn behind is random.
Not looking for exact units, just a point in the right direction.

I gave you an answer to the question you posted. The other question(s) should be posted separate.

How would one spawn an object at a specific location?

Adding new objects (basically making a copy of an inactive object) requires a reference object. The new object will inherit the transformations (location, orientation and scaling) from the reference object, rather than from the template object (the inactive object which resides at a hidden layer).
AddObject Actuator
The AddObject Actuator uses the owner as reference object. The owner is the object the actuator is configured of.
This means when you have an empty with an AddObject actuator, this empty will be the reference object while you select the template object at the actuator itself (field: Object)
Python API
The python call KX_Scene.addObject() request you to provide a template object as well as a reference object. The call should be from the scene both objects live in.
Solution
The conclusion is quite simple:
1) place the reference object at the desired location (e.g. an empty)
2) add the new object
(alternative Solution) Post processing
In some situations it might be not sufficient to relocate a reference object (just now I can't think of such a situation). In this case you can add the new object anywhere and relocate it afterwards, just by assigning a new location.
Be aware this can have side effects on physics calculations as right after creation the object will be considered as present.
Setting object Position via Python
Use attribute KX_GameObject.worldPosition.
Examples:
import mathutils

position = mathutils.Vector([0, 1, 0])
gameObject.worldPosition = position

You can even use a list.
gameObject.worldPosition = [0, 1, 0]


text:
Python - putting operator in another operator draw()
I wan't to make an operator that has button in it that is another operator, that would call some method in original operator.
In the example bellow I want to rename object, after I click on Run. Confusing part is that, although execute_function in MineTestClass is called, nothing happens. And then if I call Execute operator from Search menu, it renames object correctly.
import bpy, bmesh
import mathutils
import os
from mathutils import Vector

bpy.types.Scene.current_operator = None

class MineExecuteOperator(bpy.types.Operator):
    bl_idname = "mine.execute_operator"
    bl_label = "Execute operator"

    def execute(self, context):
        print ("Current Operator: " + str(bpy.types.Scene.current_operator))
        bpy.types.Scene.current_operator.execute_function(context)
        return {'FINISHED'}

class MineTestClass(bpy.types.Operator):
    bl_idname = "mine.test_class"
    bl_label = "Test Class"
    bl_options = {'REGISTER', 'UNDO'}

    new_name = bpy.props.StringProperty()

    def execute_function(self, context):
        obj = bpy.context.selected_objects[0]
        obj.name = self.new_name

    def invoke(self, context, event):
        bpy.types.Scene.current_operator = self
        return {"FINISHED"}

    def draw(self, context):
        layout = self.layout
        box = layout.box()
        box.prop(self, 'new_name', expand=True, text="Name")
        box.operator("mine.execute_operator", text="Run")

def register():
    bpy.utils.register_class(MineExecuteOperator)
    bpy.utils.register_class(MineTestClass)

def unregister():
    bpy.utils.unregister_class(MineExecuteOperator)
    bpy.utils.unregister_class(MineTestClass)

Let me first say I'm not really sure if this is the way to go.
A registered operator (ie options={'REGISTER', 'UNDO'}) keeps its state, that's why calling a method from another appears to have no effect.  The registered operator also needs to have an execute method for 'REDO' to work.  For example without the flag in code below a registered op will auto rename whenever the new_name field is changed.
A registered operator when run will be context.active_operator and a history of operators is kept in the context.window_manager.operators list.
Here is one take on what you want to do.  Rather than calling a method of the original op from the other, it sets a flag, that if set will rename the object.  Once again notice how changing a prop of the reg'd operator prompts a call to execute().
import bpy
from bpy.props import StringProperty, BoolProperty

class MineExecuteOperator(bpy.types.Operator):
    bl_idname = "mine.execute_operator"
    bl_label = "Execute operator"

    def execute(self, context):
        print ("Current Operator: " ,context.active_operator)
        context.active_operator.rename = True
        return {'FINISHED'}

class MineTestClass(bpy.types.Operator):
    bl_idname = "mine.test_class"
    bl_label = "Test Class"
    bl_options = {'REGISTER', 'UNDO'}

    new_name = StringProperty()
    # a flag to rename when set.
    rename = BoolProperty(default=False, options={'SKIP_SAVE'})

    def execute_function(self, context):
        obj = context.object
        obj.name = self.new_name

    def invoke(self, context, event):
        # operator invoked
        return {"FINISHED"}

    # without an execute this wont work with REDO
    def execute(self, context):
        print("EXECUTE")
        if self.rename:
            self.execute_function(context)
            self.rename = False
        return {'FINISHED'}

    def draw(self, context):
        layout = self.layout
        box = layout.box()
        box.prop(self, 'new_name', expand=True, text="Name")
        box.operator("mine.execute_operator", text="Run")

def register():
    bpy.utils.register_class(MineExecuteOperator)
    bpy.utils.register_class(MineTestClass)

def unregister():
    bpy.utils.unregister_class(MineExecuteOperator)
    bpy.utils.unregister_class(MineTestClass)

if __name__ == "__main__":
    register()


text:
Blender script won't run "Python script fail look in the console now"
I run 2.78 blender version and have this error says:
ImportError: cannot import name 'Scene'

script below:
import bpy
from bpy import Scene, Text3d, Window

helloText = Text3d.new("Hello World")
helloText.setText("Hello World!")

scn = Scene.GetCurrent()
ob = scn.objects.new(helloText)

Window.RedrawAll()

I can't see your error message, you only posted your script. Please edito you question and provide the missing info.

I put all info that I know, also blender fails to run others script

I don't really know much about bpy but do know Python. Line 5 looks quite suspect; should it be "hello.setText(...)" instead of "hello = setText(...)"?

I still get error message  in 2nd line

Please post the error.
View the consule under the menu "Window" -> "Toggle System Console"  then https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/windows_dos_copy.mspx?mfr=true (minus #1)

Run blender from through the terminal, run the script, and post the error it gives you.  We can't tell you what is wrong if we have no way of finding out.

You shouldn't need the second line anyway since the first line already imports the whole of the bpy package so Scene, Text3d and Window should be already imported.

C'mon guys, (s)he posted the script, and from that it's darn easy to determine the error message... it appears to be a 2.49 or prior script with Blender replaced by bpy.

It appears you are using the old 2.49 (and prior) API bpy is far different from the old Blender
Here is one way to add a hello world text object using the new API.
import bpy

from bpy import context

scene = context.scene
# add a new font curve and set text
font3d = bpy.data.curves.new("Text", 'FONT')
font3d.body = "Hello World"
# add a new text object
text3d = bpy.data.objects.new("Text", font3d)

# link it to the scene
scene.objects.link(text3d)

Well, when Blender says "look in the console now", you should look in the console window...
The "console window" here is not your text editor, and also not the "Python Console", but a separate window, see this question: Where does console output go

authors: Снежана Омельчук


text:
Blender Material Listing in Woodworking
I am working as a designer at a woodworking company. I am making interior designs with Blender.
I just imagine that I could use a script to print the necessary materials for the job.
The method is simple.
I created a cube where X is the grain dimension Y is the 90 degree of grain and Z is the thickness (1.8mm in most scenarios). So my key numbers is the X and Y dimensions.
I used this cube to create carcasses (various types can be achieved with a few changes) and grouped these objects. Also I created a custom property for all panel which creates the whole carcasse (sides, top, bottom, shelf etc) called "Élfólia" (Edgebanding) where I use letters to indicate which side we need to edge-band:
'A' letter is always the x dimension 'B' is always the y dimension and also big 'A' means a different type of edge-banding (called ABS) than small 'a' (called PVC). This is true for letters 'B' as well.
This is the base.
I found a script which based on the selection (which is perfectly fine for my groups) and go through all objects then saves its X and Y dimension to a file. I want to extend this output with edge-banding and area measurements in m2.
Here is the script which I use now:
# import the necessary modules we need
# in our case, blender's python API and python's os module
import bpy, os

# get the current selection
selection = bpy.context.selected_objects

# initialize a blank result variable
result = ""

for sel in selection:
# adatok lekérdez

    dims = sel.dimensions
    # write the selected object's name and dimensions to a string
    result += "%.01f x %.01f - %s\n" % (dims.x*100, dims.y*100, sel.name)

# get path to render output (usually /tmp\)
tempFolder = os.path.abspath (bpy.context.scene.render.filepath)
# make a filename
filename = os.path.join (tempFolder, "Dimensions.txt")
# open a file to write to
file = open(filename, "w")
# write the data to file
file.write(result)
# close the file
file.close()

I want to extend this script with 3 things:
1st:
In the 'for' cycle
if (there is a custom property called "Élfólia") then
write "Élfólia" content to the end of actual line
else
simply jump in a new line
2nd.
Simple math
Make an area summary from all panels. (SumArea += sel.xdimension*sel.ydimension)
and write this to the end of the file
3rd. The trickiest
I should check if there is "Élfólia" and if there is then:
check for capital "A" and if there is then SumABS += number of "A"*x dimension
check for capital "B" and if there is then SumABS += number of "B"*y dimension
check for "a" letter and if there is then SumPVC += number of "a"*x dimension
check for "b" letter and if there is then SumPVC += number of "b"*y dimension
And of course I want to write the summary to the file.
A few examples of Custom Property(Élfólia)'s content: [AAB] or [Abb] or [ab] or [a]...and so on..you get the point.
I can write code for years now but I don't know python. It would be great if you guys could help me out. Its just 5 minutes of coding if you know the right syntax but it would be a great help for our entire company :) Thanks a lot!

Just started working with something like that =)
https://blender.stackexchange.com/questions/219328/woodwork-addon-for-blender


text:
Installing blender on another drive other than C:
i just got a new pc and found out it has 2 hard drives. one with my windows 10 OS (C:)(size: 149GB) and the other virtually blank (D:)(size: 1.67TB) my question is, will blender work if i install it on my D: drive or do i need to install it on my C: drive that has my OS on it?

not true. i want to install blender on my computer, but i want it to work. my concern is if i install it on my larger D: drive that it wont work or it wont work properly because my OS and system files are on my C: drive. ive never had more then one hard drive so i dont fully understand how it works. i dont know if the second, larger drive is strictly for storage or if i can run programs from it as well. i'm sorry if it seems off topic, but im very new to this and this is very much about installation of blender on my pc.

Yes, you can install Blender on  a drive other than C. I've used it on built in hard drives "C" and "D", both as installed, and from the Zip drive installer. I've also installed it on USB thumb drives, and microSD flash drives. Note though, that even though I install to a  "D", "F", "G"  ... drive, some bits of Blender always install in Windows to a directory with a name similar to "C:Users\your name\AppData\Roaming\Blender Foundation\Blender..."

I vote to keep the question open because it is about installation of Blender.

I am so very glad this q&a was still open so many months later.  It triggered the perfect answer for me.  Good work, people.

The anwser is YES you can! You can install any software on any of the drive you have. I have my 2nd harddisk on partition. So that means I have my physical harddisk virtually cut up into 3 portion. I have D:,E: and X:. I install all my program on X: and save all my data on E: , as my C: is an SSD with only 120GB of disk space.
As it happens Blender is no exception. In fact blender comes in Zip format flavor which does not even require any conventional installation at all.
Note Change your title to "Installing blender on another drive other than C:" at least it makes the question not sound like an OS one :) cheers.

You posted this 1 year 4 months ago and it is the perfect answer for what I needed.  i.e. ignore the .msi format in favor of the .zip - so I don't fill up my SSD.   Thank you!


text:
Use part of an image sequence as specular map
I'm using Blenders plane track feature to replace a sign with an image sequence.
Now I want to add a little bit of realism to the scene so I 3D tracked it too and added a ground plane to catch the reflections of the screen. Of course I want the reflections to blend in better.
I'd like to use the ground of the background image sequence as a specular map. The asphalt is showing through and those parts should not be as reflective as the snow.
Is there some smart way to project the ground part of the background on to the plane?

Here's the background and the replaced sign I want to shine somewhat on to the snow.

What render engine are you using? It looks like cycles to me. If this is the case try increasing the rough value of your shader. Otherwise consider using the displacement modifier to break the surface up a little.

You're correct, it's cycles. Good suggestion but I want even more realism. I'll add another image to clarify.

Within Blender you can create a mask in the Image Editor, and then go into the compositor To Get This less saturated and rendered out with the Mask applied, then saved out as a Specular Map for this reason. I will play around with it, and append this answer with some screenshots/blend files/step-by-step instructions/etc...
Before I go much further, is this what you are asking for?:

Thank you and sorry for the late reply. With your help I solved it. I made a specular map version of the image sequence and mapped using the camera texture coordinates. Then I used a feathered mask to mask out the sign and blend in the glossiness.


text:
Gradient get's dark in emissive material (cycles)
In Blender I'm using a video texture (with alpha) with transparent gradients to show an interface on a wall. But while I want the gradient to give light, it makes it darker. See image below (the vertical dark gradient behind the green interface):

As you can see the gradient is making it darker, while in the video it is a light green transparent gradient.
Does anybody know why this happens?
Here is my node setup:

Please show a frame of the (.mov) in the image editor window.  Is it really 100% transparent in the likely areas?  Is that transparent BSDF color 100% white?  Can you show your mesh objects in the area of interest.  I am assuming you can add more images.  Are they any other meshes in that area?

Can you show the area in question with and without the image in the rendered.  Before and After image in render.

Thanks a lot for your replies! This was my first post. Next time I will be more descriptive...

After trying out the answer of Uncle Snail, I found out that my original settings work just fine with png files. After some testing I found out that the alpha channel in the video is the problem. In After Effects it should be set to 'Straight (Unmatted)' instead of 'Premultiplied (Matted)'. See image below. The premultiplied rendering causes a black halo around the transparent gradient.

After setting the rendering of Quiktime to Straight I got a good result:

Keep in mind that PNG files and unassociated (straight) alpha can't produce a pure emissive transparency (lighting effects are).
You have to use EXRs instead, that are associated (premultiplied) with zero alpha. In cycles just plug your texture to the emit shader and use an add shader node to add that emit shader to a transparent shader. That will give you a correct associated luminous shader that can be properly composited as light.

SIMPLE!

Plug your texture straight into the emission node, and have that go straight to the output.
Go to the "cycles settings" for your object you would like to use as a lamp.
Disable shadows and camera.

Now it will emit light, but will not cast a shadow, or be seen by the camera. Using this method also eliminates the confusion of using light path nodes.
There is an illustration below. The top render is a plane emitting light with shadow and camera turned off, and the bottom is a normal plane emitting light.

Hope this helps.

Thanks a lot for your help! While experimenting with your answer I found the answer myself. It's the alpha rendering settings in After Effects.


text:
How to unwrap a model in 3d viewport (not UV unwrap)
I have a model that looks like this

I want to unwrap it along the seam to be used for further modelling in the viewport. I want to unwrap it and re-wrap onto another cylinder of bigger radius. I think its a simple step but all my searches are leading to UV unwrapping.
Thanks in advance! :)
EDIT:
The above shape is obtained by intersection of two cylinders and then using a boolean modifier as shown below. So I can't use proportional editing on a plane to get that exact shape.

and finally I want to unwrap the shape and rewrap it along the bigger circle as shown below

Related: http://blender.stackexchange.com/q/28678/2843, http://blender.stackexchange.com/q/2351/2843

I fail to understand how this solves my problem. But its a wonderful addon. Thanks for sharing! :)

You just get answers as good as your question is ;-)

Ok so now you mention you're using a boolean modifier. Could you please tell us what do you mean by "re-wrap onto this" ? The result would look like the "inside" tube scaled larger and offset on x and y ?

There wouldn't be any scaling. The result would look like an incomplete cylinder(like a "C" shape)

Works for me using the mentioned Export Paper Model AddOn. So that was more than just a helpful hint ;-)

Pretty straight forward:

Just assign this single Seam on the "front" of your Mesh(You don't need all these Seams at the top/bottom)
Then export via the AddOn with Limit Island Size being active for it to work
Note down the Scale that the AddOn uses in the bottom left Settings Area of your File Browser and Export the SVG to a known location. You can uncheck Create Tabs and Create Numbers.
Import the SVG back again via File - Import(it will be two Curves, you just need the black one and you can remove the material, I used the "vertical Lines" here for demonstration purposes)
Scale the Model back up with the Size you wrote down aboveYou probably need to reposition it's origin - and make sure to always Apply Scale CtrlA
Position your Curve Object properly along the X-Axis standing Upright in the Z-Direction
Add a Curve Modifier with your desired "base curve" that it should wrap along to the imported Curve et voilà...Optionally you can now reposition it along the X-Axis if needed or convert your Curve to a Mesh AltC

It works! Thanks for the detailed explanation :)

I may be mistaken but I think you've gone a complicated way. It is less trivial to make a plane follow a curve than the opposite.
I propose you start with a plane instead.

Create a plane Scale it on X axis by 10
Enter edit mode (tab) and select the top and bottom edges
Subdivide by 40 (spacebar then search for Subdivide)
Enable proportional edit mode (see screenshot) and select two vertices
Move the upwards and while moving, use your mouse wheel to increase the proportional editing falloff
Exit edit mode and rotate the plane by 90° on X axis
Create a circle (shift+a, curves > circle) and scale it by 400% (that's just an example)
Make sure the circle is at coordinates 0, 0, 0
Select the plane and add a modifier called Curve
In the modifier, select the circle You should now see the plane wrapping around the circle
Adjust the scale of the plane to do a full revolution (here scale at 12.56)

And with this you're done. You can then apply the Skin modifier to the plane to give some depth. You can duplicate the plane the circle and make a smaller inner tube. There are many possibilities this way.
UV texturing is pretty easy too.

In the proportional editing mode, select another curve than what I selected to have a mesh similar to what you have.

Thanks for the answer :) but that may not solve my problem :/ Maybe my question wasn't clear. I've edited the question. Please look at it.

In the step 4: How do you know how to move the vertices to end up with a precise shape? You just eyeball it? Not exact.

of course you eyeball it, the question wasn't clear initially.


text:
How to fix when faces points on a disc are out of sync?

I have a disc where all the black dot points for every slice are in sync, except the one circled in red in the picture above. How can I get that one back into sync where it should be on the face of that slice?

Please attach your .blend

I will give the .blend file if I have to, however, I would rather be told what I did to push it out of sync in order to know how to put it back myself since I am new to blender and need to learn it more anyways....

The other thing to bare in mind is that I wouldn't of thought it was possible to screw up the symmetry of the face points without moving the slices of the disc! :s

There are too many ways to screw up, it is much easier to do it right in the first place or let others have the blend so they might figure out what you might have done wrong and help you fix it. You don't have to do anything, if you want help, it will help to make it easier

Hey WhatAMesh. I forgot where to upload the file...

https://blend-exchange.giantcowfilms.com/

It usually means that it’s number of vertices is different compared to the other faces.
If you add a vertex to one edge (i.e by subdividing the edge), the dot in the centre of the face moves towards the extra vertex.
I don’t know what you did because I can’t look at your file, but you should know that in no way does this affect your final render… these dots only show in Edit Mode.
First you need to have a look at it in ‘Vertex select’ mode by selecting the first (left) of the three buttons on the header, directly below the 3D Viewport.
If you see an extra vertex (like the one highlighted on the right of my original screen shot), then select it and delete (press X, and choose ‘Dissolve Vertices’).
Another way to check is to select the face while in ‘Face select’ mode…
and check the number of Verts indicated in the top header, above the 3D Viewport.
The one I made has one extra vertex so it tells me: Verts:4/24 (4 Verts selected out of a total of 24 on the object. It should, of course, have only 3, being a triangle.

I think I follow what you are saying SteveW. What did I actually do then to end up with this then? and how can I change it back?

Thank you! I understand what is wrong now. I found it. The outer vertice has somehow split itself in two halves and I can't consolidate them back into one. Dissolving it seems to only delete the whole slice which aint no good.I haven't completely fixed it yet but at least you have diagnosed the problemo for me. Thanks!


text:
How to use an exported Cycles image as a projected image in Unity?
I have this simple test scene with every object having a different color. It's hard to explain, but what I want to do is:

Render this 3D scene (in Cycles) from the camera view, then save the image (pic 1).
Projecting the image onto the 3D scene (pic 2).
Bring the scene with the projected image into a game engine (Unity).

My game does'nt require the camera to be moved around, so you are basically just looking at the scene from one view, so basically 2D. This is why I thought I could cheat and only show the textures that are facing the camera.
Is there any way I can accomplish this?
Please keep in mind that I want to capture the look of the rendered image in Cycles, so that I can make great looking scenes and keep that when bringing it into Unity.
(It's fine, too, if you know any other way to make an entire scene in Blender Cycles and bringing it into Inity, but maintaining that look.)

I would be tempted to just recreate each material and the lighting in Unity, as it has okay diffuse shaders by default. That way you just need to worry about getting the models into Unity, and don't need to worry about textures and UV mapping (assuming your scene won't need textures in the future).

Render your view to an image Rendered.png
Go to UV Editing
Set the right pane (3D View) to camera view (Num .)
Select Rendered.png on the image viewer on the left
Choose one of your objects
Enter Edit Mode (Tab)
Select All (A)
Press U and choose Project From View
Repeat steps 4-7 for all other visible objects
Go back to Default workspace
Open a node editor
Set up the nodes as shown

I don't know if Window Projection actually exports to Unity but I suppose there is an equivalent setting there. Actually the small cube does not need such a Texture Coordinate, and frankly I don't understand why the outer shell needs it, I was expecting it to work out of the box.

The other way would be to just bake all textures in cycles and use them in unity


text:
How to make the strings of a guitar connect with the pegs?
I need to make the strings of my guitar and I have a problem with the part where the strings connect with the pegs. I need to make the string go around the pegs. Should I make them step by step the classic way without modifiers or is there an easier way?

Well you could use curves with a curve modifier and an Array modifier
Add Your curve:

Adapt your curve:

Add a new cylinder and assing it a curve modifier and an array modfier:

Wouldn't it be easier and cleaner to just add a bevel object or directly bevel the curve?

@bstnhnsl Thats another way too! i think its a matter of choice, with the cylinder you have a little bit more control over the mesh


text:
How to simplify CAD models?
I am trying to make an interactive website (like www.3dtuning.com) using CAD models from the engineering team (.stl ) with Blend4web PLugin. But the output file size (html) was too big  (1.2GB!) so that the browser didn't display it. Then I reduced the size to 500 MB using Meshlab. The output now opens in a browser but small parts of the models are missing and 500 MB is still too big for a webpage.
Some people I spoke to say that I should model in Blender on top of the CAD models, use the Blender Models and discard the original CAD Models. This seems redundant because I am remodeling after the engineering team has already modeled it once.
Is this a normal procedure for making such websites?
I have already read other similar questions on the site, but they don't seem to have the answer.

You may want to try using Blender's limited dissolve feature OR decimate tool, it will usually clean up the faces pretty good, but it usually depends on the geometry. Because CAD models are usually more boxy than organic models, this should help a LOT.

From my own experience - make new models. This procedure is called retopology. Sometimes with simple models you can go with cleaning up mesh from CAD, but most of the time it's quicker to make new one.

You can't use the CAD models in realtime graphics they look horrible (made by engineers, not artists) and they have their faces in all the wrong places. If you want to make a good impression you need a layer that replaces CAD models with properly made realtime graphics models.


text:
Sculpting with mirror X do not match both sides
I am following a tutorial for sculpting the issue seems to happen with any of the tools but I am for this example I am using Draw. I am also using Dyntopo and mirror on X. I am trying to add the nipples and I added the one on the right side of screen. As you can see, the one on right is sharp and well defined while the one on the left is not barely popping. It is not the only place I see the issue. Is there any reason/ideas of why this is happening ?
Using Windows 11, Blender 3.1.2
Thanks in advance!!

maybe your object is not symmetrical anymore, in the panel next to the XYZ symmetry buttons, click on the Symmetrize button?

Also check that your scale is applied and that your origin is located at the center of the mesh.


text:
Beginners: Navigation/Interface question
I am sorry if this is a dumb question. I am new to blender.
I am following a demo. At some point something changed and now I have an object and the interface also shows a small xyz axis diagram on the Modeling window. It was ok for me but now When I try to move or rotate an object, the xyz axis rotates or moves instead of the object. no matter which of the 2 objects I have, any action affects only the axis but the object remains. I am using global Orientation, and Median point. I tried changing both setting with same result. My steps are: In object mode, select the object, it shows as highlighted, Click R to rotate, I start to move the mouse to rotate it and then the slected oject is no longer selected but the Axis rotates. Same when using "G": to move it. The axis move but not the object.
I am not sure how to disable this axis. See the following snapshot

You've enabled the Affect Only Origins option, it allows you to transform the object origin but you can't move anything else unless you deactivate this option:


text:
Material, UV and objects - Interface question
A newbie here.
I create an object > Add an UV map > Apply some texture. I then duplicate the object, The 2 objects are rendered properly, they show the material correctly.
I then want to change the alignment of the material in one of the objects so I select the object > go to Edit mode >  open the UV editor. Here I am expecting to see the UV mapping I previously added and also the texture file so I can move the map to align the texture, instead it shows no material and no uv map.

Thanks for any advise

Switch to Edit mode.

Ok, it was dumb. I did select the object and then switched to Edit mode but the object was getting de-selected so I had to re-select it while in Edit mode.

According to your screenshot your 3D viewport is in Object Mode, for what you're describing you want it to be in Edit Mode:


text:
Why does my Grease Pencil object become 'transparent' depending on the angle?
I am trying to determine why my grease pencil object will sometimes become 'transparent' depending on the angle I view it.
By 'transparent' I mean, other grease pencil objects that are behind it will suddenly be rendered or drawn in front of and overlap visually even though it is behind the grease pencil object in 3d space. Additionally, when the grease pencil object becomes 'transparent' it will show grid overlays that are behind it, when previously it would block it out.

In the gif example, the leaves and base of the tree trunk will 'flicker behind' the moss ball at the base which is behind the leaves 3Dimensionally. The tree is a different grease pencil object from the moss ball base. The tree stroke layers are set to 3D location and the moss ball base stroke layers are set to 2D Layers. I have toggling each of these settings but neither had an effect on this issue. I have also attempted to toggle Z pass but that didn't do anything either. I have recreated each individual component of this project and the outcome is still the same, that some angle change what gets rendered on top.
What is causing the tree grease pencil object to become 'transparent' that it will allow the moss ball grease pencil object to be rendered above it depending on the angle it is viewed in the viewport?


text:
Grid Fill multiple areas
Hey there just wondering if there's a way to grid fill multiple edge areas at the same time, ie in this rough example I know I can grid fill these selected edges...

but can I grid fill all these edges at the same time rather than having to do a second grid fill operation...

The reason I ask is because I may have a lot of grid filling to do.
Thanks in advance.

Hey :). Grid fill probably won't work here. You need two edge loops, or Blender won't know how to fill it.

Actually I might look at trying out https://blendermarket.com/products/curves-to-mesh


text:
Modelling a mess of lines for an architectural building?
I have this architectural model to build and before I leap into it, I was wondering if you had any great ideas to make the random lines of this appear over the outer walls?

http://www.nemesistudio.it/en/projects/type/culture/item/714-italy-pavilion-expo-2015-milan.html
It will be for a low poly model (ie in a game environment), so I was thinking of modelling the basic shape of the walls (eg a curved box basically) and then modelling the main lines on top (with Shrinkwrap) but making the smaller lines as a transparent png. Just keeping in mind I'm trying to make this as low in poly count as possible.
Any better ideas?
Thanks in advance.

There is an addon that comes to mind which is quite popular, by-gen by Curtis Holt, they also put up a bunch of resources about it on their youtube channel

Neither low poly nor very clean so it's not an answer, but maybe this would be of some help to you in some way: https://i.imgur.com/FWqJnS5.png The 'Bounce Spline' from 'Add Curve: Extra Objects' addon "fills" the volume of the selected object with a randomized curve. To limit it to the outer walls, created a very thin shell with a solidify modifier on a copy of my building and used that to create the Spline. Then, shrinkwrapped that onto the original building with a little offset. Two separate splines, one for thick lines and one for thin, with these settings: https://i.imgur.com/NjczIEo.png

Addon - Add Curve Extra Object
Curve -Knots - Bounce Spline

Edit:
Oh lol, Kuboå answer the same :D


text:
How to smooth bezier solid
I've made this custom lower body of a five (5) using 4 bezier curves, converted the curves into mesh and applied subdivision surface. How to smooth these faces? Shade smooth doesn't look good even with recalculated normals.

What do you mean when you say that it doesn't look good? Have enabled the Auto Smooth option in the Object Data panel > Normals? If it still doesn't work please share your file

BEFORE you convert the curve to mesh, subdivide the bezier curve once or twice, and dail up the U resolution to suit your needs. If the curve is twisting, select a point and press ctrl+T to correct the twist. Resolution of 0 will give you a square cross section. It should look smooth in both flat and smooth shading.


text:
Plane deforming while using solidify modifier
I modelled a plane into an object , I am trying to increase the thickness so I tried using the solidify modifier, but once I tried to use it my plane became distorted and uneven
Plane in object and edit mode before applying solidify ↓↓↓

plane after applying the solidify modifier  ↑ ↑ ↑
my modifier settings ↓↓↓

You can download my .blend file from this link https://we.tl/t-e7WxuNR8ab

You have some inverted normals, go in Edit mode, select all and press ShiftN.

It worked! Thanks


text:
Is it possible to set an object's location as the default location during an animation?
I'm trying to put balls into a shape that resembles a grape. The Youtube tutorial I followed ->>>>> (https://www.youtube.com/watch?v=mHawJobP_fI&t=68s)
The image below is the way I put the balls in the shape of the grape, I changed the settings so that the balls are affected by gravity and once I start playing the animation they fall into the "container".

My question is that is it possible to set the position of the balls as default during some point of the animation?
Here is how I give the balls their shape ↓↓↓

why don't you just keyframe the location when you are satisfied? then you can move the keyframe to frame 1 - if you want

Good Idea! Thanks for your help Chris :)

You are welcome


text:
How to fix HDRI not being installed properly
Im trying to install an HDRI (https://polyhaven.com/a/mutianyu) this one
but when i tried to do it while following a tutorial (https://www.youtube.com/watch?v=6VBkj_I-ONk)
this is the result I got
Can anyone help?

maybe switch to Perspective instead of Orthographic? Orthographic doesn't allow to correctly see the HDRI. If it doesn't fix the problem, please show your node setup

Double check you used an Environment Texture node for your HDRI image and not an Image Texture node.

That was the problem , I was not using an enviornment texture, thanks a lot Christopher


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Binding materials to mesh
I made a sword, gave it materials , and then I sent it to my friend. My friend got the sword in pink (When blender does not know where the textures are).  Is there any way to permanently bind the materials to the mesh? So that when another person opens the mesh the materials are already there.

This is not material issue, rather texture issue. To solve this you need to either send the other person textures that you are using for that material or go to:
File -> External Data -> Pack resources, now save your file and send it to him once again.
Now it should work as supposed to
Also please remember that if the material or world is pink, it means that there is a texture missing from the material. You sent him your file that only contains path to how to get to that texture on your PC, but he cannot access files on your PC so he needs that image packed with file


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Why is the Blender soft body physics permanent deformation not working?
At the moment I'm working on an auto crash scene. I've set up a good rigid body sim and perented a low poly car to it so that I can run a soft body sim on it and then use it to deform the high poly model.
But whatever I do the soft body sim will not have permanent deformation, even though my plastic value is at 100.

At the moment I'm working in Blender 2.79b. I really hope someone can tell me why there is no permanent deformation and what I can do about it.

I would use the fracture modifier build. It has much better collision physics. http://blenderphysics.com/fracturemodifier/

In order for the Soft Body 'plastic' setting to have a meaningful effect you need to disable the 'goal' for those vertices - otherwise the 'goal' will simply pull the vertices back to their original positions.
However, in your situation it probably isn't as simple as disabling the 'goal' since the soft body will then be subject to other forces such as gravity so you'll need to create a Vertex Group of just those vertices that would not be expected to move (eg, the wheels) that the rest of the mesh can be supported upon. In the Soft Body Goal settings you can then leave the 'goal' enabled and set the Vertex Group to limit the goal to only the desired vertices (eg, the wheels that would be resting on the floor).
This can produce the following :

In this case a Cloth simulation is, in my opinion, better suited than a soft body simulation. By setting the cloths "Structural" property to 0 you can generate permanent deformations in the cloth. With additional settings you can have it behave like metal - quite convincingly, actually.
Here is what it looks like when rendered
And here are the settings:


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How to fix shading issue on a flat face?
Here's a simple shape with two bevel modifiers and smooth shading turned on, but the shading on the flat surface is distorted and wrong. I've tried recalculating normals with CTRL N. How can I fix this problem?

Smooth shading doesn't work well with flat geometry (like yours). If you you want to smoothen your model, I would suggest applying SubSurf modifier and adding some loop cuts to your model.

Smooth shading, without further instruction, interpolates the normal at any point in a face from the normals at its corners, so your picture showing normals illustrates why the face looks curved. There are so many approaches to controlling smoothing that your question is actually quite hard to answer.. which you choose depends on other things. You could just answer "Turn on Autosmooth in the Object Data tab", but it would be wrong a lot of the time. Start here, and ask again, if any particular way gives trouble.

I found a solution to this particular problem of mine. After applying the bevel modifiers i inset the faces which where previously giving me issues. This made it near impossible to see when rendered but probably not perfect.


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Is my performance affected by invisible items?
I am making a video and I am planning to have a particle emitter to shoot lasers from my spaceship. My theory is to somehow keep it going endlessly, but control its invisibility somehow, perhaps with drivers.
Would it still be running in the background while invisible, thereby affecting the performance?

you are talking about the blender game engine or making a video?

making a video, sorry should have said that

Generally, yes, but to varying extents, and it depends.
Any object that is has "display in viewports" enabled will have its geometry evaluated.  That includes things like armature modifiers, fcurves and modifiers, constraints, even if the objects are not rendered or are hidden (hiding is not the same as disabling display in viewports.)
If you have any objects that are displayed in viewports, that depend on an object that is not displayed in viewports, those undisplayed objects will still get evaluated.  This includes dependencies on the basis of disabled modifiers or muted constraints.
Any objects that have "display in renders" disabled may still be evaluated, costing performance, but they will not cost as much performance.  Even though their modifier stacks/fcurves/constraints will be evaluated, their vertices will not be transformed for the render, they will not play a part in BVH generation, and their faces won't be rendered.  Basically, as long as they are disabled in renders, your CPU will still compute bits of them, but your GPU won't even know they exist.

Like is it still running in the background while invisible?
-> if an object is in the renderlayer, whatever the color (even invisibility) blender will still compute it ( so it will decrease performance).
If you don't need this object you can put in in another renderlayer that you don't use.
but control it's invisibility somehow
-> you can use a keyframe on the color of the material to make visible/invisble at the moment you want


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How do I script simple math functions in OSL?
I can't figure out how to script a simple inverse square root function node like the math node. The OSL language spec is mostly over my head since I don't have any programming experience.

Inverse square root - isn't that just a square?

@PGmath - probably just means 1/√X

Never mind, looked at it again the next day and it was rather obvious.. just needed a break apparently
shader invrsquareroot(
    float x = 10.0,

    output float result = 0)
{
    result = inversesqrt(x);
}


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How to get radius of a spline in animation nodes?
Similar to Is there a way to address the shrink / fatten / radius values of individual vertices on a curve with animation nodes?
I've got one main spline that acts as a driver. This spline will have many child splines that are copies of it, but the children should be offset based on the parent's size. Higher radius -> bigger offset.
The problem is, I can't find any way to access the parent's radius at a given point. Get Spline Samples and Evaluate don't have this information.
The Spline Info node can access radii, but it returns one radius for each point in the spline, and ideally the children will have much higher resolution than their parent. Is there any way to interpolate between values like the Sound Falloff node does for spectrum data? Is my best option to make second "helper" splines to store the data?

In the new beta v2.1, which you can download from the release page, the Evaluate Spline Node returns the radii of the samples:

If you can't check out the beta for any reason, I used this slightly clumsy node setup to "resize" the list I got from Spline info and interpolate the missing values.


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Chain of Hinges Physics
I am trying to model a series of meshes that are connected by hinge points. The idea is that, with some sort of sideways force applied to the first mesh in the chain, the other meshes in the chain will move around and swing on their hinges. Kind of like a toy wooden snake:

The closest I have gotten so far is by placing cubes underneath the location of each hinge point, setting them as 'Passive', and then using them as the hinge for the meshes on each side of the hinge. However this limits the movement of all of the middle meshes a lot (because they are locked by a hinge on each side) and only the first and last meshes move how I want.
Basically I need a method so that the hinge joints can swing about while also causing their own rotations. Does anyone have any advice?

I have failed to give the rigid body enough accuracy for this kind of shape :

So the idea was to use an intermediate simple object : a cube.

The chain is composed with constraints and parenting.

The parenting :

Each element of the chain is parented to a cube and each empty is parented to the previous (to the right) cube.

Constraints :

Each empty is a hinge constraint connecting the previous and next cube. Don't forget to orientate each empty with the Z along the rotation axis.

Thanks for the great demo. I hadn't thought of using an intermediary like that. I realised after posting that what I wanted was slightly different (all the rotations are done on one axis) but this method still works well just the same.

Is there any way to do this within the Game Engine? Exactly the same physics/hinges/etc, but so that it moves in response to something that the user controls?

@toysnake, unfortunately I know nothing about BGE. You should ask another question...


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Bones change rotation to first frame of last animation
I want the bones rotation of my model to be at 0,0,0 when exporting. But it automatically sets the rotation of the bones to the the first frame of the last animation used. I cant seem find anything on the internet about this and I've been looking for ages. How do i fix this?.

Make sure the action isn't still associated with the object, either via the action editor or NLA.  To see if an object has an animation look at the outliner

Here the Cube has an action (CubeAction.001) a driver and has NLA tracks.  The camera has no animation.
How to clear all animations.
Select all the bones (pose mode)  and  clear transform

You can make a "zero" animation action here by inserting a LocRotScale.

But when i save & reopen the file it goes back to how it was before. The transform doesn't stay.

Is the action still linked to the object? via either the action editor, or NLA

I think so. How can i tell, does it have anything to do with this problem?.

Has anyone got a solution?, i need to fix this as soon as possible so i can continue with my progress.

Edited my answer to show how to tell  if your rig has animation data. Given I provided it as answer, yes It may have something to do with your problem, or at least I'm under the impression it does.  If the property gui elements are (at least in default theme) yellow or green, then you have an action, if they are grey but set it is most likely NLA. Does it export ok after you have cleared the transforms.

I'm quite new to blender i know most modeling tools (I think) but I've just finished going through some animation tutorials which only explained how to animate objects so sorry if this is nooby question but if i have to remove the action from the object (Which i think is what i have to do from how you explained your answer) wont that delete the animation?.

It unlinks it from the object (a user) . Objects, actions (all blender datablocks) are only deleted if they have zero users, you can prevent this by setting the fake user https://www.blender.org/manual/data_system/datablocks.html#fake-user

When i cleared animations they wont play anymore when i export to unity engine and after clearing animations, 7 animations start to show up for the model: Idle, Bones|Idle, Bones|Running, Bones|Walk, Character|Idle, Character|Running, Character|Walk,? Can you explain this, is there hidden animations somewhere or something?. Its not really a big problem but its kinda bugging me since there's 7 animations when i only need 3.


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Python Scripting, add hotkey with map type Mouse?
I want to add a hotkey by script. The regular Addon tutorial mentions how to add a normal hotkey. But i need a Map Type Mouse, left mouse button, with holding down a modifier key. And i run into trouble here.
My current code is
kmi = km.keymap_items.new("view3d.paint_select", map_type = 'MOUSE', type = 'LEFTMOUSE', value = 'PRESS', key_modifier = 'I')

And i get this error:
TypeError: KeyMapItems.new(): was called with invalid keyword argument(s) (map_type), expected (idname, type, value, any, shift, ctrl, alt, oskey, key_modifier, head)

map_type is missing in the expected list of keywords. But where else should i put it then? Is map_type not part of KeyMapItem?

I think there is no map_type parameter in the 'new' function. See https://www.blender.org/api/blender_python_api_2_77_1/bpy.types.KeyMapItems.html#bpy.types.KeyMapItems.new. 'LEFTMOUSE' is enough to indicate this is from the mouse

Shift+LMB example to toggle Properties > Scene > Simplify:
import bpy

# operator
class ToggleSimplify(bpy.types.Operator):
    bl_idname = "view3d.toggle_simplify"
    bl_label = "Toggle Simplify"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):
        context.scene.render.use_simplify = not context.scene.render.use_simplify
        return {'FINISHED'}

addon_keymaps = []
# register
def register():
    bpy.utils.register_class(ToggleSimplify)

    # handle the keymap
    wm = bpy.context.window_manager
    kc = wm.keyconfigs.addon
    if kc:
        km = wm.keyconfigs.addon.keymaps.new(name='3D View', space_type='VIEW_3D')
        kmi = km.keymap_items.new(ToggleSimplify.bl_idname, type='LEFTMOUSE', value='PRESS', shift=True)
        addon_keymaps.append((km, kmi))

# unregister
def unregister():

    for km, kmi in addon_keymaps:
        km.keymap_items.remove(kmi)
    addon_keymaps.clear()

    bpy.utils.unregister_class(ToggleSimplify)

if __name__ == "__main__":
    register()

Also see: https://www.blender.org/api/blender_python_api_current/bpy.types.KeyMapItems.html

Thank you, you were both right. It's enough to use type='LEFTMOUSE' . That's what i was searching for :)


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Rotationally stretch or compress 3D texture around Z axis
I want to distort a 3D texture around the Z axis in Cycles.
I found here that you can convert cartesian texture coortinates to polar coordinates but the problem is that you end up with a projected 2D texture. I want to preserve all the 3 dimensions and stretch or squash the texture around the Z axis to get a behavior like this :

...but with 3D texture coordinates.
Can we achieve that with Cycles nodes ?

you want to scale a texture around the Z axis, or do you want to create the effect shown on the bottom image, or is the texture intended to control the distortion of the objects?

I want to scale the texture around the Z axis which would give the effect on the bottom image except not with meshes but instead a 3D texture (like noise or voronoi). So if I were to use volume scattering I would get the same behavior. Of course there would be a half plane in which the texture would disappear as I would scale it down which would create a seam, just like for the Cartesian to Polar coordinates conversion.

I swear I did this by accident yesterday answering another question.
Trying to find it.

Please find it back !

Sorry, not sure what did it, I know I was messing with the scale, mapping node, separating the XYZ and some math nodes in between, I saw that effect and tought that it looked neat, and then went on because what I was lookign for had nothing to do with that.
Also it probably wasn't a clean answer either, because I suspect the real answer is probably much more complex, Im going to give it a whirl, but I think this might be above my possibilities.

Let us continue this discussion in chat.

Found it.
The idea is to use a gradient node in radial mode and plug it to the angle of a rotation node (just like a Mapping node but with an input socket for the rotation). Since such a node doesn't exist in Blender we make it with math nodes.
First the rotation node itself (it's a node group) :

then the general setup (the green node is the rotation we made above and the yellow node is the one to animate (the second value in the Multiply node) :

Result :

Here is the file :

Why put in an answer that says "I found a solution and I am currently making this reply that I will edit..."? Just write your answer, then post it.

no kidding it was simple >.< great solution, looks really fun!

Just for illustration of what I PM earlier..

this solution is also great, tough I don't understand the math behind it, super elegant!

yes but the result is not as clean towards the center (the texture converges to it). You can see it when looking from the top.


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Is there a better way to move around and view a big scene?
My problem is that I have a huge scene with meshes and (let's say) I see this scene for the first time. I do not know it, I want to look around. I can use the controls like
MMB  plus look around, ⇧ Shift + RMB  (but scene is too huge for this).
Then I select some objects on the hierarchy and press numpad . (but as I said: I do not know the scene and/or the object names can look like all the same as well), what will take me there.
I know, I can use the fly camera mode, but that is well... kinda hard to use, for me at least. Is there a better way to move around? Like in a game: WASD + mouse look? (I do not want to move my camera, my goal is to move my editing area to a specific position / angle)

Related: http://blender.stackexchange.com/q/3327/599

Also see: http://blender.stackexchange.com/q/644/55

Since 2.70 there is a walk mode (like a game). Press Shift F to enter walk mode. Then use either WASD or the arrow keys to walk and the mouse to look around.
To speed up walk mode.

during walk mode you can point the mouse cross hairs at any object and press space to teleport there. (I find it really neat)
holding shift will speed up any of the movements.
NumPad + or Mouse-Wheel up to increase the movement speed for that one time, when you exit walk mode the speed goes back to what it is set at (see next point). There is no feed back to changing the speed, just hold the button for a bit. Likewise NumPad - and Mouse-Wheel scrolling down will decrease the speed.
If you want to make any lasting speed changes you can go the the user preferences, on the input tab down on the left is a section for the walk mode entitled View Navigation. Change the Walk Speed, also the Speed Factor is how much holding shift or alt will change the speed.

If you want to zoom right in on any object or objects with NumPad . you can select the objects in the 3D view, you do not have to select them in the Outliner.

Like David said, the walk mode since 2.70 is a good way to start.
Additionally I want to add this:
http://wiki.blender.org/index.php/Doc:2.6/Manual/3D_interaction/Navigating/3D_View/Navigation_Modes
You can adjust the speed with Mousewheel Up/Down
And you can also start the Fly Mode with Tab
Teleport to a point with Space

Set up cameras for each view you might want then select one in the outliner and switch to it in view menu.

For anyone looking to replicate the navigation in other 3D software I've been able to come close. The solution below allows you to press the middle mouse button then you can navigate the scene using wasd and moving the mouse.
Go to Edit... Preferences... Keymap...
Search for "View Navigation (Walk/Fly)" (AKA: view3d.navigate) and set it to middle mouse button like this:

Delete these two interfering mappings by clicking the "X" on the right of them (or change them but you probably won't need them anymore with the new navigation style) :

(This ones hard to find I search for "middle mouse" and scroll...) Delete it:

Unlike other 3D software this activates when you click the middle mouse button not by holding it in (which I would prefer let me know if you figure out how, I've asked here). This means you need to disable it when you want to go back to doing something else by left clicking, right click makes you jump back to the last location you were at, which I'd prefer it didn't do.
I also tried to associate this with the right mouse button but didn't have any luck due to it interfering with the context menu and so many other things.

Super cool stuff! You answer gave me a push into trying Blender again. I got a step further even: I got it so that on right mouse button press I enter into Walk/Fly Mode and on right mouse button release I leave it. The trick is to bind "View3D Walk Model" -> confirm to right mouse button release. I also used a python script to change all other right mouse button actions to require the alt key pressed as well.

Blender 4.0
⇧ Shift +  ` Walk Navigation
View > Navigation > Walk Navigation

Much better than Fly Navigation, follow @DoubleVoid hints


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Select all layers upon selection
So I have this asset, which is single object in blender

and when I use Select Box on one part of object it only selects top layer

but all others that are not visible, are not selected

so the question is - how to select all layers of object below the cursor, even those that are not visible/obscured by other layers?

So I asked this question on OpenVFX discord and got my answer - I need to switch to xray mode

You can also use ALT-Z to switch in and out of x-ray mode (and SHIFT-Z for wireframe but that on its own will not enable x-ray mode). In your case you could also hover over one of those objects and press 'L' (linked) to select the whole object.

thanks for suggestions!
L key did not work for me, probably it has some geometry problem, still only selects part of object https://imgur.com/F88H7qC

Yes. I assume that objects been imported from other software? Looks as if you have overlapping vertices. try selecting all and pressing 'M' > Merge by Distance and see what is reported in the centre of the bottom toolbar.


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How to Move Objects Precisely in Axes Other Than X,Y, and Z?
I am a beginner in Blender, so far I have googled the question I asked in the caption of this post, and haven't been able to find an answer for it.
Using G and moving it in X Y Z, or using middle mouse and moving objects in the aforementioned directions are so easy. But imagine if you want to move objects precisely in let's say, between X, and Y axes?
It is very irritating for me to only be able to move objects in direction of X, Y, and Z. I know I can go to top view and move them in any direction I want. But I would like to move them accurately. Last time I made a turbine and rotated it. The turbine blade had an animation and it was rotating on X axis, but as soon as I turned the turbine to direction between X, and Y, its blade went haywire, and rotated in a messed up manner, like it was loose or something.
I would like to know if there is any shortcut or hotkey to move objects in various directions precisely?
If not, how professionals move the objects accurately in any direction?

Of course, you can just G and move an object freely.
You can also hit G shift Z and move an object freely on its XY plane.  Same for shift X, shift Y.
You can also change the orientation that you're using, from Global to Local, or Normal, or View (or some others.)
You can also create a custom orientation from another object or face by selecting it and using "Create orientation" operation (ctrl alt space for me.)
You can also parent things (which would be useful for your turbine, likely) so that you can move or rotate the parent in its local axes, rather than those of the child.
You can even hit G X X to move only on the local x-axis of your object. Same for Y and Z.
Same for G shift Z shift Z -> moves only on local xy-plane.


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How long it takes to render in Freestyle mode?
I am a beginner in Blender, and I have a question for you if you can help me.
I have a scene with multiple objects and a total of 1,731,619 triangles and I am rendering in Eevee in Freestyle.
I have two computers, one is a Mac M1 and the other one is a Windows with a CPU AMD Ryzen 5 3500X, 6x 3.60 GHz, GPU NVIDIA GeForce GTX 1660 Super 6GB and RAM 16GB.
I am testing both computers to render a frame with a resolution 1920 x 1080 px and the result is:
MAC M1: 39 sec
WINDOWS: 1 min and 03 sec
It seems that both computers uses normally the CPU and GPU, but the memory is used to the maximum.
My question is:

Is it normal, for computers with good qualities, to take so long to render in freestyle?
Am I doing something wrong?
Is the scene too heavy?
Or do I just need more memory? Do you think that if I buy 32 GB of RAM it would make a difference? Or should I just get a better computer?

Thanks in advance for your help!

On my behalf I can say my hardware is mostly like your Windows PC and yes, it is a heavy scene. From my personal experience I can tell that getting more RAM will help but it's not creating magic ;) Surely a better computer will improve things, the question how much you want to spend and how much better it will get... that's hard to tell beforehand, surely we cannot tell in precise numbers like render time in seconds for example. What helped me with heavy smoke simulations that crashed was rendering from the command line. Not only they didn't crash after a while, they also rendered much faster.

Thank you Gordon!

I suggest you to use Grease Pencil instead of Freestyle, there you get also more freedom to define whre you want to have intersections and where not. Grease Oencil can interprete also already set Freestyle edges.
Basically calculating outlines or lines in 3D can be very time consuming.

Thank you Christoph. I ll try it!


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How to keep the object size constant while it is moving?
I need to move an object in depth without automatically changing its size. Is it possible?
Blender automatically scales the object's size when the object is moved in depth according to the principles of perspective. I want to manually control the scaling.

If you  place your pivot point at the camera ( e.g. 3D cursor to camera, then '3D Cursor' selected as pivot center), when you scale your object in all axes (or any element of it, in edit mode,) the shape will not appear to change in perspective, when seen through the camera. If you then want to 'scale the object manually', you can do that in some other space, say, by setting the pivot to 'Median Point'.

This is the basis of camera mapping, and trompe l'oeil effects

This is great for grease pencil projects where you need to move objects relative to the camera without changing the size of the drawing in the camera view.

One option is to use Drivers to automatically set the scale based on the distance to the camera. This way, whenever the object or the camera moves the object will automatically scale to match.
To achieve this, add drivers to the Scale properties of your objects (move the mouse over the Scale properties and press Ctrl+D). Set each of the driver as Type 'Scripted Expression', Expr 'var / 10' (use a different constant in place of '10' for a different 'at rest' scale - how many units away from the camera that the scale should be '1'), the variable type (the icon alongside the variable name ('var')) to Distance, and set Object 1 and Object 2 for the object and the camera (both using World Space). Do the same for each of the X, Y, Z channels.

Now, moving the object (Cube) should result in the scale automatically adjusting to suit.
NOTE : You might need to go into User Preferences and enable the Auto Run Python Scripts option on the File tab to enable Scripted Expressions.
If all is set up correctly this should now produce the following result :

(To explain the animated image, the cube is moving purely along the X/Y plane - no vertical motion at all. From the top view you can see its motion along the grid and how it actually changes scale depending on how far it is from the camera (bottom-right). From the camera's perspective it appears that the object doesn't change size at all - it also doesn't appear to move away from or towards the camera but this is an optical illusion due to its changing scale - at its most distant (towards the top edge of the top view) you can see the grid overlap the bottom of the cube when viewed from the camera when it's at its largest scale)

Object is not changing its size, but only seems to be smaller due to perspective.
I suppose what you need is:

Pressing 5 on the Numpad turns off perspective. (Or other way: View -> View Persp/Ortho).
Pressing
S on the keyboard lets you scale the object.

Something I am currently using is going to the camera settings and changing the "Lens" option from perspective to orthographic. Then things stay the same size unless scaled manually.


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How to make small objects emit a ton of light?
So, I'm trying to create a chemical plant model, and you know how when you drive past an oil refinery at night it's all lit up with dozens of lights and it looks really cool?
That's what I'm going for, but the problem is, my model is HUGE! And when I make the sphere that asks as the light bulbs and I only add a basic emission shader it doesn't give off enough light and if I increase the strength it only makes the light more intense.
You can see here, the light isn't giving off anywhere near enough light:

Try using the default lamp objects instead of only the emission material.

Mesh lights can be useful but they are quite an inefficient way to light your scene - especially with a large number of small lights as in your case. A better solution is to use Point Lamps to light the scene - although those are not visible to the camera which is not the effect you are looking for.
The solution is to use a Point Lamp embedded in the center of what would normally be your mesh lamp. This way the scene is lit by the Point Lamp (and can take advantage of all the optimisations in the renderer for handling point lamps) while the mesh lamp is still visible to the camera - but is set up to not block light from the lamp.
You can achieve this using the following material :

The Is Camera Ray light path input is used to switch between a Transparent shader and an Emission shader depending on whether visible to the camera. This means that for illuminating the scene the mesh will be invisible (so the lamp is visible) but in the actual render the mesh will emit light as if it were lighting the scene (so any effects in compositing (such as a Fog Glow) will still take account of the brightness).
As a comparison, here is a scene using a mesh lamp with 20 samples. The lamp on the right is a Point Lamp (and so is not visible) while the one on the left is a mesh lamp and so if visible to the camera. Note how the mesh lamp is very poor quality. Many more samples would be required to get acceptable results.

Using the above material produces the following result. Note how the mesh lamp is still visible but that the Point Lamp (positioned inside the mesh and set with a similar size as the mesh) is providing the actual illumination. Again, this is with only 20 render samples but the result is much more pleasing than the mesh lamp.

There is already a great technical answer on how you should use a real light instead of a mesh to light the scene. So I will go into the artistic side a bit more:
When you see a strong lightsource, what you are actually seeing is:

How the nearby surfaces are lit by it. -This can be accomplished by just cranking up the energy value of the lamp.
The light is scattered due to the air and dust around it. This is what creates a visible beam or halo around a light source. - When used subtly, it can convey a lot about the intensity of the light.
When the light goes through the optics of a camera, it scatters again. The intensity and size of the glow is critical in conveying the brightness of the lamp.

In this before/after, the ember on the right appears much brighter simply due to bloom and scattering.


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Why does my mesh change when i render it?
I'v created an animation with a simple displace modifier and textures and it looks just fine in rendered view, but as soon as I hit "render" it deforms to this low poly mess. What am I doing wrong?

Recommend having modifier settings in screenshot, and / or upload a demo file

Are your render subsurf levels different from the viewport levels?

Modifiers can be disabled in viewport and/or render. The subsurf and multires modifiers also have different settings for render and viewport.
The camera icon controls the render view and the eye icon controls the viewport.


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How to clear all keys of all objects and bone?
Is there any way to clear or delete all the key frames of all object and bones?
I created an animation, but now I only want the model and not the animation. Selecting each bone and deleting every key frame is very tiresome job. I tried selecting all object and pressing alt I, but somehow the key frames still come back when I select a single bone.

Using scripts
Often for repetitive (& tedious) tasks it is handy to use a small script.
Remove all actions in file
Keyframed animation data is stored in an action. To completely remove all keyframed animation data, can remove all actions in the file.
import bpy
for a in bpy.data.actions:
    bpy.data.actions.remove(a)

Clear all animation data on scene and scene objects
To remove animation (actions, NLA, drivers) from scene objects and scene, but keep the actions in file.
import bpy
scene = bpy.context.scene
scene.animation_data_clear()
for o in scene.objects:
    o.animation_data_clear()

1.Go to animations tab, select the object's bone for which you want to delete animation.
2.Enter into pose mode,  and Press A key twice (deselect and selects all bones).
3.Now on the left side, all the animation keys will appear and they turn into orange color indicating that all are selected.
4.Now move your mouse cursor over the curves and hit Del key then select delete keyframes.

Make sure you have a timeline view open.  (Or a few other choices.)

Select all objects.  In object mode.

In timeline view, select all.  (Same-ish interface here, just hit 'a' with your mouse cursor over the timeline for me.)

Delete keyframes in timeline view.  (x->delete keyframes.)


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How to make an animation node particle wiggle?
I wonder if it is possible to have an existing particle setup (keyed) and then use an animation particle node that follows those nodes, but with a wiggle effect.
I have been trying particle nodes the whole day now, but with no results at all. The idea is that some object instance would wiggle around (normal) the particle setup.

AN won't work for keyed particles, as it is not possible to just read data from them with bpy... you will need to use two particle systems and interpolate between them in AN using vector mix node, then add the wiggle

Start by getting the particles from an object, each item from that list is an individual particle which you can get the location of by connecting to a particle info node. Then you mix a vector wiggle to the particle location and use that to set the location of an object.
Here I take the original particle z location and mix a wiggle into the x and y location to place an object that follows the particle downwards.

Add that into a loop to repeat for each particle.

well i see one object (i used cube) woble now, but its only one, and i wonder how to have each particle be followed by a wobling causin.
Also it doesnt seam to follow the particle (some how the cube wobles mostly around 0,0,0 coordinates.


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How do I export blender textures as png in cycles?
I just modeled this knife and I can't find how to export its texture as png.

I searched a lot, but nothing seems to work. I tried baking it a few times, but all I got is a black UV map. And yes, it is unwrapped. When I baked it using combined bake type it baked the texture together with the light that was reflected of it.

Is this what you are looking for? https://youtu.be/Tj-S5QAac3U


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Problem with the size of object in the blender interface after changing to a bigger monitor
I recently changed my monitor with a bigger one. Windows normally controls the zoom of the apps, but I found some problems in blender. In edit mode for example the cross of the pointer is so small that I can't see it. I tried to increase the dpi from settings and the problem is partially resolved. Anyways, the arrow and other things are really small, so I can't work as well as I would in edit mode and so on. How can I solve this problem?

In order to enlarge the cursor size, font size and the overall windows, you can always go to User Preferences by pressing CTRL+ALT+U or by navigating through File drop-down menu. You will find many options there. Two such options are depicted below. Scale your blender Windows accordingly and check on Large Cursors. Navigate through other options and you will eventually get a good view of the cursor and Windows. Alternatively, you can also use Windows Magnifier to see Whats there on the screen from a fairly far distance. Don't forget to Save changes.

"Large Cursors" seems to be gone in recent versions.