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Adding an edge loop to a pyramid
I have created a pyramid by adding a cube, then selecting the 4 upper vertices and clicking Alt + m, then "To Center":

I would not like to make the sharp top "dull".
There should not be a sharp end anymore, but instead I would like to create something like this:

To do that, I tried to insert an edge loop into the pyramid.
However, this doesn't work: It only wants to insert an edge loop at the "ground" of the pyramid (where we still have 4 vertices), but not on top.
I'm stuck. How could I resolve this?
Thank you!
Edit: I found out that the Knife tool allows me to cut my pyramid. Is there a smarter solution anyways?

See https://blender.stackexchange.com/questions/24781/how-to-loopcut-a-square-based-pyramid. Sides of the pyramid are triangles which aren't available for cuting with Loopcut

Instead of knife tool you can just select edges and use W->Subdivide operation, it works on triangles and N-gons as well. But just a thought: if you intend to cut off the tip, you already had a cube, you could have just scaled the top face smaller to achieve the same result.

One quick way is to use Offset Edge Slide tool. Select bottom face and run it (depending on the version) either with Ctrl+Shift+R or via viewport menus:

Add two edge loops on either side of selected loops.

Offset Edge Slide
Since there aren't any faces on the other side of the selected face before using the command, no extraneous edges will be added and you don't need to dissolve any unnecessary geometry in this case.

Not exactly an answer to your question, but there may be an easier way to make the surface in your reference, which shows you can leave the rounding to Catmull-Clark subdivision. Working in the XY plane....

Start with a manually subdivided plane, (here, 8 cuts,) and from all vertices selected, in the header Select menu, hit 'Checker Deselect'

GZ move the selected vertices up in Z, and assign a Subdivision modifier, level 2.

The subdivision on the perimeter is unconstrained by adjacent vertices, prodicing higher peaks, so we'll get rid of them.

Apply the modifier
With all faces selected, Select > Loops > Boundary Loop
CtrlNumpad + increase the selection from the outside. I found 6 steps worked with this mesh..

Deleting the selected faces leaves you with a tileable section of a surface like the one in your illustration:

You can decide where to cut it and extrude the perimeter to give it thickness, when the size is settled.
EDIT: (response to comment)
This is working in the same way for me in Blender 2.80..

Thank you so much! While not exactely the answer to the question, your approach is an amazing piece of art! Thank you!!

With Blender 2.8, I don't have to apply your steps mentioned in the section ranging from "The subdivision..." to "this mesh.". With Blender 2.80 Beta, I can skip this step. I wanted to get these sharp for a test with the Modifier attached, but I can't get these sharp spikes. Do you think you could perhaps check this? Or is it too early with Blender 2.80beta?

I have uploaded a video here that shows what I'm experiencing: https://youtu.be/baS_cHY3grg

@tmighty.. see edit.. in the modifier,  the UV settings and 'Use Crease' shouldn't make a difference here.. 'Quality' makes some difference at the  corners, which will be deleted anyway. Is it just that you're not moving the vertices far enough? (Note  dimensions) After nudging the checkerboard vertices up in Z, you can scale all  vertices in Z about their median to give a more centered result..

If you want to add a loop cut you can use the knife tool. Look at the pyramid from an ortho view such as the front. Select the knife K and then hit Z and C (K + Z + C). It will auto cut back faces (Z = cut through). Start the cut outside of the pyramid and drag across.

https://easyblend.org/html/modeling/meshes/editing/subdividing/knife_subdivide.html


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Shading issue when adding Subdivision Modifier
Firt things first, needless to say that I'm still a newbie haha.
I've been learning how to model with extruding vertex and faces, instead of starting from a cube.
Everything went pretty well until I decided to add a Subdivision Surface modifier to smooth everything and I found this(Also happens when I right click and check shade smooth):

Also I let you see the X-Ray version, which made worry:

So thanks in advance and any help would be appreciated :3

Hi and welcome to Blender Stack Exchange. Please show and tell. A little more information about what you mean would be really helpful. Please read this to learn how you could help us to give good answers.

Looks originally like "Normal" problem. this post will give you an idea about it. it happens a lot when models are extruded.
Blender How to Recalculate Normals

Thank you mate :D I'll save this for future references

Fixed by deleting the faces and adding them again.

Hey :). In the future, you can just recalculate face orientation. Some faces are visibly flipped in your x-ray view. Good luck with your project.

Oh thank you :) I'll keep that in mind for future cases hehe

source: Stack Exchange

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

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Blender texture baking?? Can we bake blender cycle material into texture with bump included
Blender texture baking?? Can we bake blender cycle material into texture with bump included....
Or Anybody please explain how to export from blender(cycles) to unity with material

Google "how to bake normals blender" or "texture from blender to unity". Basically, try to research if someone else has already answered the question before asking it on this platform. Sorry I don't mean to be rude but this specially true when new to a software as there is a good chance someone has already faced the same problem and avoids duplicated questions...

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


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Rig deforms my mesh
I rigged this robot here and weight painted its arm. The joints are right I think because the other arm moves fine, but when i rotate this one the mesh becomes deformed. I don't know what the problem is, I've made sure to paint the entire arm too.

If a part of your robot does not deform, can simply parent the part directly to the bone, without having an armature modifier.  Can you upload your blend https://blend-exchange.giantcowfilms.com

it looks like a dirty weight painting. Try to use another approach - just go to the edit mode, select the whole arm, and set its vertex group's weight with the assign button (weight = 1). I think it will do.

If you want a vertex to solidly move with a bone, assigning a weight of 1.0 is not enough: you need also to delete any weight referred to every other bone: It looks like the deforming vertices of your mesh are weighted also to some others bones.
To check one vertex and see which weights it has, select it in edit mode and search in the "N" properties panel the "vertex weight" panel.


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Metallic object reflecting dynamic sky instead of hdri
I created a sky texture using dynamic sky and hdri.
I use lightning from dynamic sky and sky texture from hdri (only texture not its light)  using mix shader and light path(is camera ray)
Now i have a metallic object it is reflecting dynamic sky not hdri. I want it to reflect hdri what i can do ??

"Is Reflection Ray"?

no is camera ray. i understand the problem , acutally object is relfecting the light striking on it and the light is coming from dynamic sky not hdri but i want it reflect hdri because its visible in enviroment not dynamic sky what i can do

I meant, have you tried combining Is Reflection Ray into the mix?

No its also not working.

Did you try in Cycles? I am not sure the Sky texture works in Eevee..

hm... since you want to light up your scene with the sky... all light bouncing should be a reflection so you can't avoid seeing the sky there, unless you do some compositing.

yes i want to only light up the scene from dynamic sky not it want to present in the enviroment so if the sky is pink object should reflect pink not the dynamic sky

I believe that's what I illustrated in my answer below. My "dynamic sky" is green and illuminates the scene where as the environment is pink and is showing in the background and on reflections.

YA BUT USING DIFFUSE RAY ENVIROMENT IS PINK {COLOR FIRST INPUT NODE} AS WEL AS LIGHT IS ALSO PINK MEANS THE COLOR GREEN HAS NO ROLE. I INCREASE STRENGTH OF BACKGROUND NODE OF GREEN COLOR BUT NOTHING CHANGE IN ENVIROMENT

Please don't use all capitals in your comments. This is considered shouting and rude.

I added another screenshot showing that the green "sky" strenght is working. Please doublecheck your setup, you must have made a mistake.

sorry i dont know

added blend file FYI...

Is Diffuse Ray might work for you. Here I simulate your HDRI with pink and your Sky with green (the ground has a white diffuse shader).
Here is the blend file:

no its not working both in eevee as welll as cycle

what do you mean? Please explain.

thanks its working. Thank you very much


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Geometry behind glass material appears slanted in render
When I render an image, there are bevels somewhere on it that shouldn't be there. How to fix it?

It almost appears like it's index of refraction hitting the hard normals of triangulated geometry. Have you tried rendering with glass set to auto smooth? Turn the glass object off during render and see if distortion occurs? Give the glass a shiny reflective MatCap material and check if normals reflect oddly?

@CobyRandal yes, without glass all is fine, i added modifer and the problem desapiar, thanks

@CobyRandal Form it as a response so I can mark it as a solution

Ok will do! What modifier did you add that worked for you?

It almost appears like it's index of refraction hitting the hard normals of triangulated geometry. Have you tried rendering with glass set to auto smooth (Object Data Properties>Normals>Auto Smooth)? Turn the glass object off during render and see if distortion occurs. Give the glass a shiny reflective MatCap material and check if normals reflect oddly. Some modifiers that can help (depending on if you want sharp or smooth glass): 1. Weighted Normal 2. Edge Split. You typically use them separately.


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How can to do the inverse of explode modifier in Blender
How can to do the inverse of explode modifier in Blender
like the text "CHRIS MACARI" at the beginning in this video
Here is a GIF of this section

You may do it using the Video Sequence Editor.

Go to the Video Sequence Editor window (Sequencer) and add the scene animation strip to it (Shift+A-->Scene-->Scene). Check the Backwards checkbox in the Filter panel of the properties shelf (press N being in the Video Sequence Editor window).

Press the Image Preview button to see the preview of your animation. Render animation with F12.

I made this addon:
How to reverse an animation?
(It contains details on excatly how to do a reverse explosion)
It allows much greater control than simply running the explosion backwards as seen above, although that can be useful.

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


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Shape appears different in Edit Mode and Object Mode
So this is my first model. And the shape appears different in Edit Mode and Object Mode.

Can someone please explain me why it is piking out like that?

Have you applied modifier? It can be turned off in edit mode but turned on again when in layout mode.

only mirror modifier

it looks like one misplaced vertex. Try to fix it or use bisect at the modifier.


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Weird artifacts when importing texture to Unity
I have this tree texture that I UV Mapped and the bark should be a single color as it is in Blender. But when I import the texture and apply it to the model in Unity I get these dark stripes. I have tried changing the compression values of the UV Map image but it doesn't really do anything.
Thanks a lot for any suggestions.
Edit: Turns out it was the emission value of the material in blender. I had put the same color as the base color but way darker as suggested in a YouTube tutorial but when I put the same value as the base color the lines disappeared.

Unity is less precise when it comes to texture sampling. This means, it can accidentally pick a pixel outside the UV island. Can you show the texture, preferably with the UV Layout?

@FrederikSteinmetz Yeah I've realized that after reading a few other posts. I uploaded the UV Map, hopefully that's what you meant.


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How to use the rotation matrix calculated by Matlab in Blender?
Good morning,
For a project, I created in MATLAB a scene composed of an object and twelve cameras looking at it. With the tool box of MATALB, I got the rotation matrix and the translation vector for each camera.
Now I would like to use these information (rotation matrix and translation vector) to create the same scene in Blender.
So I want to use the translation vector to position correctly my cameras in the space, so I will modify the location parameters in Blender with it.
I want to use the rotation matrix to get the correct rotation of my cameras in the space. So I will modify the rotation parameters with it.
The panel I am using  is this one:

For the rotation, I know in Blender, I can use the quaternion, the euler rotation angles (XYZ, YXZ, ZYX) or the axis vector. I calculated all of them with MATLAB but unfortunately they don't give the correct result. The cameras don't look in the correct direction as shown on the following pictures:

Camera's view:

What I would like is the camera looking at the object like on the following picture but with the parameters calculated by MATLAB. In this example, I use the object constraint properties:

So, in the view of the camera, we can see the object:

The rotation matrix of the first camera is:

Its translation is:

The XYZ angle calculated with this matrix by MATLAB is:

I read that MATLAB and Blender don't have the same coordinate system.
How can I do that?
Thanks for your help.

We are going to need a lot more info in order to address your issue.  Could you please add some screenshots of your setup and an example of what is different between the two?

Hi,
I would like to use the parameters calculated by MATALB to define my model to built it with Blender.
Sorry, I will ask a stupid question but how I can share here the screenshots from my computer?

See this meta post.  Use the add image button when editing your post.

Thanks for your help.
Let me know if it is still unclear.

Welcome Noella... One particular thing missing here is, values of  the MATLAB rotation matrix  and what the rotation is. Eg Euler XYZ in degrees of  (23, 45, 55) This will tell us if it is row or column order.... or look it up.

See https://blender.stackexchange.com/a/176762/15543  the camera in blender looks down its -Z axis and pitches on Y.  If you know the MATLAB camera FORWARD and UP can use https://blender.stackexchange.com/questions/102293/how-to-properly-use-exporthelpers-axis-conversion-method

Thanks for your answer. I edited my post with the information you asked me. I had a look at your two links. The first one doesn't seem to answer my question. The second could be a possibility. The problem is I don't answer how to use it. I tried the code but I don't understand how to indicate to Blender that I want to use the camera axes, and I don't understand how to pass to the function the rotation angles calculated by MATALB.

Some rattling on.
Not sure one arbitrary rotation matrix and one location vector with very little more info is enough. Instead of a very long commment, here is some ways to try and work this out.
The matrices given.
>>> print(R)
<Matrix 3x3 (-0.4877,  0.8728,  0.0190)
            ( 0.4404,  0.2648, -0.8578)
            (-0.7537, -0.4100, -0.5136)>

 T = Matrix.Translation((1.5581, 1.2190, 1.4871))

In blender (row order matrix) the columns of a 3x3 rotation matrix are the vectors of local axes.  If the camera was placed such that it focused directly on (0, 0, 0) (In blender a camera looks down its $-Z$ axis)
For example in default blend, with a track to constraint on camera to look at cube at (0, 0, 0)
>>> C.object
bpy.data.objects['Camera']

>>> print(C.object.matrix_world.to_3x3())
<Matrix 3x3 (0.6563, -0.3579,  0.6642)
            (0.7545,  0.3114, -0.5778)
            (0.0000,  0.8803,  0.4744)>

>>> print(C.object.matrix_world.translation.normalized())
<Vector (0.6642, -0.5778, 0.4744)>

ie its local  $Z$ axis matches its normalized location
if it was same for given data would expect
>>> T.translation.normalized()[:]
(0.6295621991157532, 0.4925462305545807, 0.6008740663528442)

to match a column (or row, not sure of order) of rotation matrix, unfortunately it does not,.
Using angles given to  get this matrix by setting order to ZYX and transposing
>>> print(Euler((map(radians, (141.4, -48.9, -137.9))), 'ZYX').to_matrix().transposed())
<Matrix 3x3 (-0.4878,  0.8728,  0.0187)
            ( 0.4407,  0.2647, -0.8577)
            (-0.7536, -0.4101, -0.5138)>

Reversed order suggests pitch, roll, yaw type rotation.
Transposing suggests either column order of matrices, it is also a cheap way of inverting a rotation matrix.
>>> print(Euler((map(radians, (141.4, -48.9, -137.9))), 'ZYX').to_matrix().inverted())
<Matrix 3x3 (-0.4878,  0.8728,  0.0187)
            ( 0.4407,  0.2647, -0.8577)
            (-0.7536, -0.4101, -0.5138)>

Which also suggests there could be a difference in +/- for CW / CCW rotation.
>>> print(Euler((map(radians, (-141.4, 48.9, 137.9))), 'XYZ').to_matrix())
<Matrix 3x3 (-0.4878,  0.8728,  0.0187)
            ( 0.4407,  0.2647, -0.8577)
            (-0.7536, -0.4101, -0.5138)>

Seeing what happens, set the matrix world to
C.object.matrix_world = T @ R.to_4x4()

for the hell of it in this one have used
C.object.matrix_world = T @ R.transposed().to_4x4()

since it is easy to see in image that (if the object of interest to focus is around (0, 0, 0)  it's looking the wrong way and is upside down.
Can make a conversion matrix via
>>> bpy_extras.io_utils.axis_conversion(
...         from_forward='Z',
...         from_up='-Y',
...         to_forward='-Z',
...         to_up='Y')

Matrix(((1.0, 0.0, 0.0),
        (0.0, -1.0, 0.0),
        (0.0, 0.0, -1.0)))

Or can see that flipping 180 degrees around $X$ axis would give same result.
>>> Matrix.Rotation(pi, 3, 'X')
Matrix(((1.0, 0.0, 0.0),
        (0.0, -1.0, -8.742277657347586e-08),
        (0.0, 8.742277657347586e-08, -1.0)))

So with one of the conversion matrices above as S
>>> S = Matrix.Rotation(pi, 4, 'X')
>>> C.object.matrix_world @= S

In as much as it doesn't exactly answer your question, I hope it gives enough info that if you have two locations and a rotation from each that points directly at a known point (eg the origin) then it would be a relatively easy task to work out the space.

Hi,
Thanks for your answer.
I tried to write the script step by step, according to your answer.
I wrote this script (I put it in my next comment) but I have an error when I try to calculate Camera.matrix_world = T @ R.transposed().to_4x4()
I searched on the internet, but I found nothing. Why I have the following message:
expected a sequence of float, not float.
Otherwise, I will try this script when the problem on this line will be sorted out, and see if it is the solution of my problem or the start of a possible solution.
Thanks a lot for your help.

Sounds like you have missed some brackets.a = ((1, 0), (0, 1)) as opposed to  b = (1, 0, 0, 1) first element of a is a sequence of floats, first element of b is a float.

Thanks, it was that.
I tried what you told me. The position of my camera does not match with your screenshots.
Is it possible by comment to share what I have on my screen and the code?


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Is there any other way to model this archway?
I want to make a hole to a plane in this way but it's taking so much time. I deleted faces and added spin to a vertex and joined the vertices I want to make it even easier is there any other way to make this

"is there any other way to do this?" Please use a descriptive title that sumarizes the specific content of the question

how to make the curve on the top,easily

use subdivision modifier? Round stuff is usually achived by using subdiv, bevel or boolean. Spin is also a good and fast option if you dont do it for the first time.

Sounds like a job for Proportional editing.
Set it to Sphere faloff and adjust size to your liking.

THANK YOU IM SEARCHING FOR THIS TYPE


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How to recalculate normals?
in version of Blender 2.72, where is the option recalculate?.
Like in this video https://www.youtube.com/watch?v=IZPqxADetWE&feature=player_detailpage#t=108
Here is a screenshot:

If you don't see the Shading/UVs tab in the Tools menu, make sure you're in Edit Mode.

'Toolbar tabs' were implemented in 2.70. You can recalculate the normals from the 'Shading/UVs' tab of the tool shelf (revealed with T), or you can do it by a short cut by Ctrl+N

I don't see this menu


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Objects disappearing when zoomin in and out
I want to make a 3D from a 2-dimensional floor plan in dxf. Size around 28 '(9m) X 54' (17m). I can see my plan when I open it but as soon as I want to zoom in or out I lose it because it immediately becomes too big or too small
How can I adjust the zoom according to the dimensions objects I create?
Thanks in advance!

I'm not sure I understand what you mean but try this:

Open the N panel menu.
Go to the View tab.
Set the Camera Clip Start value to a lower value than the current one.

Thanks for your fast response! I try it with no success in the 3D workspace :-( When I try with a top view the zoom work properly


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Cycles Render Lighting Glitch While Using Transparent Normals Map
i just have a question that i couldn't solve myself. The thing is i started to use substance designer and get my own custom textures from there, but the normal map it generates is transparent. I do know how to change it from transparent to non-transparent image but the transparent map looks better in my case. Anyway, in the cycles render whenever i render my object, there will be lighting issues. I am pretty sure the normal map is making this problem. Please i need this question to be answered asap. Here are some pictures of the issue and the transparent normal map. P.S The map is a png file and the light is smack right in the middle, so one half is lit up and the other isnt.
I also found out that the glossy shader is broken with this kind of normal map, there is a "void" in the reflection which moves with the camera:

From what I'm seeing in other discussions about this around the web (1, 2), Substance Designer embeds a height map in the alpha channel of the normal map PNG. In other words, the way Allegorithmic is using it in their normal maps "alpha" means height/bump, not transparency.
Theoretically this is convenient because only one PNG needs to be loaded into memory to provide both height and normal data. In practice some render engines, including Cycles will be confused by this, as Cycles quietly passes the alpha channel along with the RGB data. Cycles does not anticipate RGBA data being fed into a normal input socket - it expects RGB only.
The way to strip that out is by using a Separate RGB node, followed by a Combine RGB node. Then you can connect that RGB normal data as usual.
If you will be doing this often you might want to Group these nodes together and save that group in your startup .blend.
Now what about that alpha channel containing the height data? Let's not let it go to waste. Here's how to use both height and normal data together in Cycles.
Remember to specify that the image texture is of the type "Non-Color Data".

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


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Annoying Bone Rotation Glitch?
My english is bad. I apologize for my bad english.
I've been watching tutorials and learning on my own too, but I cannot seem to be able to find a solution to this problem in particular, or maybe I simply don't know how to describe it. :(
Context
I am rigging a large dragon model for a game. When it comes to the tail bones, I have 3 bones making his tail and they have the limit rotation constraint, but the bones seem to ignore the constraint.
When I'm testing the Y-axis rotation limit, instead of going up and down, it makes a kind of an "S" shape slide. Funny and weird, because the bone seems to be entirely ignoring the restriction to not rotate over the X-axis.
This animation will clarify what I mean:

Summary: when I test Rotation on Y-Axis on the tail, first up/down, then it goes to right/left. The tail moves in an "S" shape even though the X-axis is limited to 0:0. I honestly don't know much about rotation engines or measures like Euler or quaternion, I haven't messed with that yet.
I attached a .blend file for further comprehension of my issue.
EDIT
Thanks for the elegant edit of this post, forgot to link the .blend file
https://drive.google.com/file/d/14nmny0wEqOcibfAlXmsPhZO7ZNUYfxFa/view

Did you apply rotation to your mesh? I had a slightly similar issue and not applying rotation to the mesh solved it.

I had a look at your blend file and everything seems fine to me. I think you have some misconceptions about local and global space. Try to align the tail bones properly, and look at the axes again. Use the manipulator widget in local mode to see what axis you are actually rotating on and then you'll understand that the constraint works fine, but the axis of the bone and what you want the bone to do don't match up.

The rig is working OK. If you bring up the transform manipulator and set it to rotate on local access:

You can visually see the orientation of your bones:

The red circle is x-axis etc. Clicking on these sequentially gives the range of movement you stipulate in the constraint. Notice x-axis is on an orientation I assume you would want the tail to move but you've set it to zero. The "s" shape movement you describe happens when you try to force movement in a direction that is choked by the constraint.
I also noticed that the bone roll doesn't quite agree with the orientation of the tail (all the bones are diagonal to the axis). I hit ctrl-n and chose global +z in edit mode to recalculate the tail bones. This ensured up/down, side-to-side but not twist movement - again assuming this is what you wanted.
ps. Nice model
Edit: I notice TeeTrinker has already answered in the comments as I was typing this LOL.

Thank you for helping me. As TeeTrinker said i had misconceptions about local and global spaces, in the animation i provided i rotated over the Y-Axis hoping the tail to go Up+/Down- but after the d8sconz method of recalculate roll, The Global Y-Axis is now the X-Axis of the bone locally, so i applied the rotation constraints based on the global space and not local space, the tail still makin "S" shape rotation, but now in the allowed constraint min/max range, but if i edit degree values manually i can get the results i wanted. Thank you both, that was the slap i needed to open my eyes.


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Character disappearing, normals are good
I have all the normals of my mesh are all recalculated and I Turned on backface culling for good measure but my mesh still disappears when I press p.enter image description here(Thank you for answering, I've decided to make this game first person instead.

In the viewport if you are in textured view does everything look right?

oh, yes, everything looks right

That tells me that there is something going on that is causing your object to be physically moved out of view, and not just turned transparent . Try parenting your camera to the disappearing object and see what happens. Also check to make sure you don't have conflicting collisions. For your character only the collision box should have any collisions, everything else should be set to no collision.

yes, I know, and that's what i have, no collision

Some points to check:

When you do not see the object at all, the normals are normally not the problem. Unless all faces are facing away from the camera you should see at least something. On a closed mesh it is not possible that all faces are facing away from camera when the camera is outside of the mesh.
And there we are: ensure your object is within the camera's frustum (the view of the camera). The object should not be behind the camera, or above or somewhere else.
Ensure all parents of the object are supported by the BGE. E.g. parenting your mesh to a curve. The curve is not supported and therefore not loaded. The mesh as child will not be loaded too.
Check if the mesh and the parent are at a place you expect them to be. Start from top view. Use wireframe mode too se through the faces. Add a cube and parent the character to it. Un-parent the skin mesh to see it is rendered at all. Switch the armature to rest pose etc. These are little steps to see if it changes something.

Remarks: You should only enable backface culling when simulating very thin objects where you might be able to see both sides at the same time (like paper sheets, leaves or curtains). It doubles the workload of the renderer.

darn, I tried all that and none of it worked.

In that case ... please post a demo file.

I've decided to do something different with my game, so do not worry.


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Can't perform boolean difference with an imported collada object
I imported a Collada file created on Photoshop (turning a png into 3d plane), then extruded it in Blender.
The reason for that is that this is a complex object to create with curves myself so I figured it's a faster approach.
Then I try to cut through some objects with this extrusion using the boolean modifier - difference, but I never seem to get this to work properly. Either getting "Cannot execute boolean operation" or it just won't cut the objects at all.
Tried modifying the boxes with the imported object as target, and the other way around too...
I tried to use the knife project by selecting a box and the imported project but I get an error on "no other selected objects for projection" error.
I tried removing doubles and fixing the normals.
Nothing helped so far...
Here's the Blender file -
What can I fix for that to work?
This is my first Blender project btw...
Please don't mark as duplicate because I already mentioned that I perofrmed the actions described in other posts and it didn't help.

Welcome to bse Please use http://blend-exchange.giantcowfilms.com/ for blend files.  Paste All files will be removed after time making the link dead for future readers of this question.

unfortunately it's not a duplicate... I already checked all other occurrences of this matter before posting. Also I updated the link to the blender file.

It seems to be working in the .blend file you uploaded. You realize that after you Apply the Boolean Modifier your bull/buffalo object will still be there. You need to hide it and move it to another layer/ turn render for it off or delete it.

I accidentally uploaded the wrong file. Now uploaded the correct file relevant to the question. The file I uploaded by mistake included an object created from curves, but the file I am referring to (which is now available in the link above) contains the imported object I referred to in the question. Thanks for notifying me...

I already mentioned in the original post that I fixed the normals. Is there anything I missed?


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Selecting faces not covered by other objects
I have a mesh of a terrain with seperate models of a large building and various roads and parking lots on top of it. I wanted to add a tree particle system to the faces of the terrain not covered by the building and roads and I wanted to know if there was a way to select only the faces that are not covered. All of the faces that I want to select are visible when looking from above.

Please show your work as a Blender screen capture.

Please click on the image to see a larger image. Particles are emitted in the areas not covered by buildings as explained below.  A flat plane is the terrain.  A torus and cone represent simple buildings.  The buildings are in wire mesh mode to indicate no particles are in that area of the terrain.  The yellow arrow shows  the particle [density influence] with a check mark.

In the image above the building area have been expanded by blurring in a 2D image manipulation program. Perhaps Blender. Blur, Dilate, Erode can be used.  This helps to eliminate trees placed too close to buildings.

In the particle panel, Textures can determine the areas of particle emission.
The plane has a UV projection.  Use that UV projection as needed.
GIMP image manipulation was used. GIMP is free. Use the image manipulation tool of your choice.
You can hand paint the image if that suits your tastes in what follows below or use the other tools that come with your image editor.
You can easily render and create an image of the top view of your scene, with orthographic projection. I used a low quality workbench render with flat colors. You may choose to temporarily have your terrain in an unusual color such as bright green as in green screen for the top view render.  You can save a single image with a name such as image001.png.
Use an image manipulation tool to process the image001.png for about 33 seconds, to increase contrast if necessary, and building area dilation. This image can be processed to achieve a gray scale or black and white image.  In the first image above you see a green and white image. Next it was processed to get the solid green and solid black image for high contrast. Black for no trees. White or Bright for trees. The new image was saved as image002.  Use this image002.png to control emission density.  Of course choose image names that are suited to your tastes.
A texture slot was added in the particles panel. The same texture slot was edited with the texture panel to change the [Influence Density]. The image image002.png was specified.
Please inspect and improve any steps.

Can also bake to obtain the texture (probably above a vertical sun light)..

"You may choose to temporarily have your terrain in an unusual color "  - would it be a good idea to use the material index / object index in the compositor for that?

As @lemon has commented, an alternative method for generating the raw texture might be to temporarily disable all your lighting, replace with a Sun lamp pointing vertically down in Z, and (using Cycles) bake a shadow map, as shown on the left.

If you set the angle of the lamp wide, to get a soft shadow map, you can have some control over the margin between the buildings and the trees, by putting the texture through a color ramp, and out into an Emission shader. You can then re-bake the resulting Emission.
Optionally, retouching can all be done inside Blender, using Texture Paint.

Can we call you Robin Bestt?

@lemon Moi? You could try, but I don't think my extraordinary humility would permit it.

Another way is to use vertex weights.
But this technique needs either :

That you group all of your objects into one (Object > Join when selecting multiple objects)
Use as many "vertex weights proximity" modifiers as you have different obstructing objects.
Create a "proxy" object mesh which will encompass all your other objects. You can then deactivate rendering for this object and hide it in viewport or set it to bounding box display so that it doesn't bother you.

So :

Add a vertex group to your terrain
Add a particle system to your terrain set to Hair
In the "Vertex groups" foldout of the particle system, set the "Density" to your group

Important : In Emission > Source, check "Use modifier stack"

Add a "Vertex Weight proximity" modifier to your terrain. Place it in first position, before the particle system. Set the Vertex group to your newly created group, the object to the obstructing object. Set the distance to geometry, and you can SHIFT + Drag to select Vertex, Edge and Face. Set the fallof to median step. Keep "Lowest" to 0 and crank up Highest till your trees visibly get pushed out of your geometry.

Note : It won't update directly if you move the obstructing object. You need to toggle off/on the particle system for it to update. It will update if you move the terrain itself.

Nice because it doesn't depend on the resolution of a bitmap. I guess you could link the terrain to a 'Canvas' collection, and all the buildings to a 'Brushes' collection and abuse Dynamic Paint as a way into a Vertex Weight layer, too.

Right that would remove the hassle of going around having multiple obstructing objects !


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Wave Modifier Physics
::Edit::
Thank you, respondents.
I now have the desired z-transforming camera, the second part of my question is: I would like a sphere to be able to roll on top of the wavy plane due to the wave motion of the plane.
I can't seem to get the sphere object to make contact with the wavy plane during animation. The ball should rise and fall with the wave, and also roll due to gravity when the wave is vertical under the ball. I have it close, but the ball is going through the wavy plane.

Please visit http://gph.is/2EpCrto for a better gif picture.
The ball's y-transform is locked because it kept going off the side. The plane's and ball's rigid body source includes all modifiers via "final" mode. There is no collision modifier yet applied to the ball.
The Blender Docs mention something that could be of help: "The changing collision shape is available also with Change Shape button in the Physics tab of the Tool Shelf."
https://docs.blender.org/manual/en/dev/physics/rigid_body/properties.html#rigid-body
Thank you.
Answered - ::I would like to modify a mesh, either a plane or cube, to have a wave modifier. I would like an object to rest on the surface of this wavy plane and receive forces from it. Basically, I want the object to transform its Z-location value (Z axis is up) based on the waves of the plane. I do not wish to use the Ocean modifier.
So far, I've had minimal success; the wave-riding object seems to accept vertical forces from the waves but it's awkward, unrealistic, and just not right. What's the right way to have a stick-mounted camera move up and down with the waves?
Thank you.::

it would help if you further describe what you want to achieve.  Are you trying to animate an object on the surface of the plane, or the camera, or both (together/separately)?  Are you looking for realistic waves as one might find in a real body of water (and if so, how big?), or stylized sine-type waves?  When you say "wave modifier," do you mean that you actually need to use that particular modifier, and if so why?  what's wrong with the ocean modifier?  in what way is  your object's motion "unrealistic"?  are you looking for "bobbing" like https://www.youtube.com/watch?v=q23WFVrQ7GI

The link you provided is actually what I used as guidance before asking this question. As you can see, he used the ocean modifier. I think my problem is that my wavy plane is an "array"-modified object, so the three vertexes that I select apply to all the copies of the wavy plane, which skews the motion of the wave-riding object.
I've now reduced my experiment to using one plane and now have the camera motion I desired.

Please don't write "Thank you" between every line, don't say "answered" and don't write "Edit" every time you edit the question, we can see exactly what you edited.

Please don't exaggerate in order to belittle others. I am a polite and grateful person. I thank three times, whereas there are 13 "lines", do you mean sentences? Otherwise, your exaggerated claim would appear as an attempt to defame me.

@silvermanj7 I meant a markdown line (paragraph), but it is not my point. Sorry if exaggerated. I simply was advising you to a better question format for the future. The first line in your question is "Edit : Thank you", don't you think that this is a bad way to start a question? and the sentence repeat two or three times. Thank the community by upvoting, accepting answers as well as participating. Also, edit log is available, so you don't have to type in "Edit" unless necessary.

Create an empty where your object touches the surface. It's usually good to have an inbetween empty for additional freedom.
Go into edit mode of your mesh with the modifier.
Select the empty with CTRLLMB. Then select 3 verts of your mesh that are close to the point where the object swims.
Hit CTRLP to make a vertex parent, formerly know as face parent.
Now that's not exactly forces acting on the object, but the parented empty does what the 3 verts tell it to do. Now you can parent anything to the empty and adjust it.
If you use only one vertex as parent, rotation will not be taken into consideration and the empty will only be moved.
You could be even more flexible by having several empties with several single vertex vertex parents and then use constraints between the empties to handle the rotation of the master empty that bears the camera.

This works for me because I can use the actual empty object to manipulate my camera as desired. Thanks, Haunt_House.

This technique is not a physics based simulation, it is just a fake approximation but might yield what you are after.

Just add a single faced small planar object above your "wave surface" object.
Add a Shrink Wrap modifier to it and set it to Project mode. Make sure you tick the Negative option if necessary.

This will make your object stick to the waving surface. Now just parent whatever object your want to this plane and use Duplifaces from the Properties Window > Object Tab > Duplication > Faces to duplicate it at the face center.

I agree that this one's better since you can still place the camera elsewhere.

Yours works fine too :). Upvoted

Likewise. I used the shrinkwrap on several occasions just like you describe. I'm a bit absent minded of late.

I can't seem to get anything to move by parenting it to the shrink-wrapped object because the origin of that shrink-wrapped object never changes.

You are probably missing the Duplifaces Step


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having trouble getting rid of unwanted vertices
reworked my model and now can not get rid of stray vertices ,how do I get rid of unwanted Vertices on a model?

If they're close to useful vertices you can try remove doubles, if not you can select an useful vertex, then press Ctrl L (select linked) then press H to hide them; if the mesh has more useful parts go on and hide all useful vertices, then A to select all (unuseful) and X to delete.


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Boolean operation BUG?
I can not properly cut out holes with boolean modifier. Difference or Union looks very similar. The object with which I want to cut (5 cylinders) after cutting always sticks on the shape that I want to cut (after choosing difference). Tried flipping normals and triangulation modifier on all shapes. But nothing helps! Begging for some wise words!

have you given a bit of thickness to your plate? I guess it will work if you do, use the Solidify modifier, apply it, then try again boolean

Nice, it worked! Thanks a lot, moonboots !

Use a Solidify modifier to give thickness to your plate, apply it, then try again. Boolean needs thickness. If you don't want to give thickness to your object, use the Knife Project tool.


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How to avoid faces overlapping when bridging edge loops
I want to create a bottom wall and to do it i add a circle and then use "bridge edge loop"

But the result is strange:

I don't want a face also inside circle (beacause it will be a hole).
I hope can you help me and sorry for my english

you don't need the central circle, just extrude with E, press enter, scale inwards, then W > LoopTools > Circle. Enable the LoopTools addon if it's not the case already

Duplicate that loop and Scale it down.
Make it a circle.
Select both loops and apply the bridge.
See the images below.


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How to avoid misplaced objects when importing into Blender
I am new at blender so i dont understand much of it, i've got a problem at the moment of importing an ifc file as all the objects are in the same axis and not distributed in parts that should be. I will leave a video so it can be understanded better. On the top it shows how it should look, and on the bottom it shows how is imported.

In what software was this model exported?

It was exported from Revit.

This issue is usually caused on export, not import, if transform methods were not applied upon export, the export method will not detect a software dependant transform, modifier, or parenting, try to check the options when exporting the objects, if there are options to apply transform and modifiers, make sure to check them. There's nothing much you can do on import since the data was not exported properly.


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Is it possible to execute copy/paste operations using Blender interface?
this may be a weird question. I started rendering my animation on my school computer and I left it overnight. How forgetful I was! I set the rendered images to save to the tmp folder not the folder I created. So now when I go to the 'output' section on the render tab and clicked on the folder icon next to it, I see all my rendered pngs but the thing is that I can't drag all the pngs to the folder that I created. I also can't access the tmp folder on the windows computer manually itself as I don't have an administrator password. So I'm wondering is there a way to drag all the rendered pngs out from Blender program itself to the folder I created?

The 'output' section on Blender I know it does say 'tmp' now that is because I'm now starting to render again.

Rendered PNGs

Is your question about copying files using Blender interface?

Yes. Sorry for any misunderstanding.

@root can you write this as an answer?

@root it doesn't work?

@root You're right, it can help him in this situation though

@cegaton The reason why I'm asking is because IT is too busy today fixing things and no students are allowed to go to IT. I had already started the rendering process again. I'll delete this question if  you want me to.

@cegaton Alright then

If the file is protected by windows, presumably it will stop programs from entering there, otherwise it would be way to easy to bypass the protection password, so just of a guess, it may not be possible. (I'm no expert though)


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cloth keeps pulsing when simulating on rigged character
I'm new to cloth Physics in blender and I'm trying to simulate cloth on a cape rigged to my character. It wont stop blowing or pulsing even when the character stops moving in the animation. I've tried several things that solved similar problems in other questions to no avail. For example, I increased the poly count, collision settings and weight and it still pulses. The mesh isn't going inside one of the collision meshes either
Here's a little gif showing the issue

Just let me know if you need the model and I'll share the link


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Why does parenting to a bone put the object at the bone *tail*?
This is a question mostly for my curiosity, because I figure there's probably something I'm missing.
When I parent an object (an empty) to a bone in an armature, the object gets placed at the bone tail. (The object has the identity transform.) To the extent that the bone has a location, isn't it the bone head? So why move the child to a location that's a somewhat arbitrary distance from the bone's actual location?
And as long as we're here--what transformation space is the object in once I've done that? If I parent to another object, the child object's transformation space is relative to its parent. If I parent to a bone, is it relative to the bone's world transformation? That would be logical but I'm having trouble with it.
Thanks for any insight.
--
E.g.: I have Suzanne set up with an armature with a single bone and a single unparented Empty hanging out at the origin:

I parent the Empty to the bone with this code:
bpy.data.objects['Empty'].parent = bpy.data.objects['Armature']
bpy.data.objects['Empty'].parent_type = 'BONE'
bpy.data.objects['Empty'].parent_bone = "Bone"

The result is the empty is moved to the bone tail position:

If I parent an empty to a bone, it will stay where it is and keep its location values, so I'm not sure what you mean. And it works as if you parented it to an object. Maybe show a sceenshot?

Sure, I added an example. Maybe the behavior is different if you do it through the UI? --No, just tried that and the empty moved.

Hey, I played around with this and confirmed what you were saying.  It is weird, and I don't know why Blender's coded that way.  In typical use, when you parent anything, you'll be creating an inverse at the same time that controls what the local space of the child is (including the origin of that space, whether it be at the tail or head.)  Because the tail has the exact same transform as the bone as a whole, it doesn't matter to what Blender measures the inverse.  But I agree, it's weird.  (The object transform, in this case, is relative to the bone's local, rest orientation.)

The only thing I can guess is it's an artifact of child bones having their reference lines running to their parent's tail. But it's a PITA for me.


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Custom Split Normals in view vs. in python
I have a mesh with custom split normals. When I look at the normals on the loops through python I see the values I expect, but when I look at the split normals visually in edit mode, they are quite different--and the shading matches what the view is showing.
How do I get the view to show the custom normal data I see in the mesh data with python?
I've tried C.object.data.calc_normals_split() but that copies the values I see in the view into the values I see in python. I want to go the other way.
Details:
C.object.data.loops[1967].vertex_index
492

C.object.data.loops[1967].normal
Vector((-0.5192142128944397, 0.7101643681526184, 0.4754820466041565))

Viewing the object in edit mode with vertex 492 selected, showing split normals:

You can see the y and z values of this split normal are negative whereas they are positive when I printed the loop normal.

Can you post screenshots of what it is you experiencing/ looking for? It's unclear just by reading.

Thanks - sure, added the code I'm using to test and an image

Your problem is that there is a difference between a loop and vertex. Loop is a combination of one edge and one vertex. More info. I'm inclined to believe that if you're looking for the different split normals vectors for each vert then you'll want to go for something like obj.data.polygons.verts or in bmesh bm.faces.verts. Just looping over the verts by themselves will only produce the averaged normal, the split normals are most likely stored in the polygons or maybe the loops.

Yes, I know loop normals and vertex normals are different--that's why I was getting the normal from the loop in the example. And the normal in the pic is the split normal (cuz it's magenta.) Not sure about polygons and what they'd give. But see the answer I just posted.

Turns out I needed to run update() on the mesh before trying to set the normals, and then I never got into the weird state in the question. I would love a tutorial on when the update() and calc_*() functions need to be called.


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Merge two armatures
I have a scene with a lot of armatures and I want them to be only one rigged big model but merging them with Ctrl+J break all the animations

do you have any idea how to fix this?
EDIT: I'm not sure that my post is a duplicate of the other one, I managed to join the armatures by having proper names, then merging the two objects (Crtl+J), Applying transforms, putting two armature modifiers on the object instead of one, and finally, merging the armatures ...
The weights are ok, but there is two problems: the action of the second armature is deleted and the armature is like slightly deformed ,
to fix the action missing I've copied the action before the merge and paste it in the graph editor after the merge, at first the animation kinda looks like it works, but then it goes all over the place ...
EDIT2:
so it's not possible to merge armature with the actions attached to it, plus merging armatures with scales not applied properly (and I can't apply scales on it because it breaks the animations) deforms everything.
It seems that there is no solution apart from do all the animations again (1600 frames), something that a can't afford to do, in other words, I'm f****d,  its a project I've been working on for weeks and there is no solution.
I'm depressed right now

You could try merging the armatures into groups. That might work a little bit better than one whole group.

I'm not sure it's a good idea, it's going to make your work much harder in my opinion. Besides that, in 2.8 you can switch several armatures to Pose mode


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Masking out parts of an object for compositing
I am making a model of an Arc Reactor. In the model, there are some wires and a sphere with emission material, inside a glass material to create a glow effect.
Now I want to make these emitting objects glow and add flares in post-processing, so I was wondering if I could Isolate the emitting objects and mask out the objects in front of it so that I can mix the two images in post processing to make the whole thing glow.
Thanks.
My Final render:

Emitting surfaces only:

What I want (kind of):

Also, I think that the center ball-like emitting piece will block the foreground of the render which I don't want; So what would be a good way to composite it?
Thank you.

Why do you need to mask for a glow? Isolating via masks will likely end up with a less than ideal output.

So what would recommend if I want to add a glow around the object?

This might be of some help to you: https://www.youtube.com/watch?v=nMo67qBqc_0

Simply keep the scene referred ratios, and apply a generic glow. If you need an outer ring emission, model it.

Can you please elaborate on how can I model the outer ring emission? I have tried increasing the emission value but I loose the details. Actually I want the ring to glow but the glow should be blocked by the copper wire pieces.


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Modelling a modern dome tent
I am trying to model a dome tent with four sides for an outdoor night scene but I cannot figure out the modelling approach. I have seen this question and it helps to make the basic shape, but I want to make it as real as possible with big wrinkles and stuff. I have tried sculpting and cloth sim with pinning and stuff but it doesn't look good.
So if you can tell how would approach it, it would be really helpful.
Thanks.

have you checked this? https://blender.stackexchange.com/questions/102020/is-there-a-better-way-to-make-complex-cloth-than-sculpting-it?rq=1

Thanks. This would help but still I would not be able to create the stretching effect along the corners and where the pipe is attaches to the cloth.

You could try inflating a square pyramid, or something like it, using Rich Colburn's Modeling Cloth

I think you should get something pretty good with sculpting, you just need to observe how the fabric behaves. Here's a quick try, I've given the object a Multiresolution modifier, when you're fine you can bake the normals, delete the Multiresolution modifier and use the normal map on the original low-res version.

Looks pretty good. Are you using any specific brushes of the default ones? Also, any idea how to create the stretches where the tent is clipped to the frame?

I've added the wireframe, it's just the basic shape with a bevel on each corner. For the brushes: I'm very bad at sculpting so I just used the basic SculptDraw brush, sometimes brought some corrections with shift or ctrl, I guess with some experience you can do much better, but again the key thing is to see how the fabric behaves. Now maybe it's feasible with cloth physic simulation but I don't know enough about cloth...

Thanks. I'm actually waiting if someone answers using cloth sim with better results or I'll accept this :)


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Activating Vertices and Edges selecting modes simultaneously
How can i convert from Edges to Vertices selection, in my modeling? I need to keep Edges and Vertices selected, not to switch selection from Edges to Vertices.

In 3D View, you can change your selection mode by clicking the related buttons (check the image) you can activate 1 selection mode, or 2 by pressing Shift and clicking the related button, or you can activate all of them using the same method, so you can activate Vertices, Edges and Faces selection modes at the same time.
In the image you can see I have both Vertices and Edges selection modes activated.

It converted my selection. Thanks, it works

While the information Georges provided is correct, there is an alternate method that I sometimes find useful, the hotkey combination CTRLTAB. This opens a dialog box in which one can select vertex, edge, or face mode, though not more than one mode at the same time.


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Modeling a cylindrical object to resemble an image reference
I'm trying un-successfuly to model the cylinderical shape in the reference image. I tried simple deform, But that results in pinching artifacts. unlike basic circle model. Please how can I make it the right way? With right workflow. Thanks

I believe the best way is to use Boolean intersection using small cylinders to carve the edges, or using BoolTool addon, which will give you more freedom editing the Boolean operation before applying it.

1- Model the main object and the shape to use for Boolean modifier.

2- Select the main object, in Modifiers panel, add a Boolean modifier, assign the object you want to extract under (Object) in Boolean modifier.

3- Choose Difference as the Method, then Apply the modifier.
4- Delete the extraction object or move it to another layer.

The disadvantage of this method is that it'll create Ngons, yet since this a radial symmetrical object, you can model 1/8th of the object first, use the Boolean modifier and apply it, fix the Ngons by connecting vertices using J or using knife tool K, then copy rotate it 45 degrees, in order to get the whole object.

thks for your solution sir....

You are most welcome :)


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How to avoid gaps in mesh when using smooth
I downloaded this hat mesh online, and it is originally polygonal.
I want it to be smooth, so I use the smooth tool and....
It turns into some weird web of faces. The only solution I thought of is painstakingly selecting EVERY edge, and pressing "F" to close the gap.
Is there a way I can fill the gaps automatically, or prevent this from happening when I use the smooth tool?

This is happening because the faces are separate from one another. You can join them together by going into edit mode on the original mesh, selecting all, and then doing “Merge -> By distance”. Smooth should then work correctly.

Thank you very much! That was it!

@Diio Your welcome. PTL!


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Applying physics to hair in Blender 3
When i apply physics to an object and press space button object is moving but hair is not moving.
I was advised to bake the hair stimulation in the hair particles system cache settings, however, that didn't work for me.
I watched a YouTube video were the user enables the advanced setting and hair dynamics, unfortunately, following the same steps didn't work in my case. Is there something I should do different since I'm using Blender 3.0?

pls provide your blend file so we can check it out...or watch again the tutorial carefully and follow each step which is taken. But without seeing any settings of your work we cannot say what you did wrong so pls improve your question. Thanks. And a link to the tutorial you watched would help too.

Is not about blend file i just click shift A and add  uv sphere or cube after that i click on particle properties and add hair   after that i click on physics properties and add rigid body to object  but when i click space button object is moving due to gravity but hair is not moving with object

Add UV-Sphere, add rigid body, choose source "base"

add particle system, hair, check hair dynamics
result:

Note: if you just "change" your particle system i might be necessary to delete your cache


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Hats for characters
I have a character with a hat and separate shoes. Should I be joining all separate objects when i'm about to rig a character?
Edit:
What are the benefits of each method, joining the parts in own object vs Keeping them separate.

I'd be inclined to parent them to your character. That way you could still have the wind blow his hat off without having to separate it from the body mesh! Select the character, then SHFT select the hat and CTRL-P > Object (Keep transform). You can then move the character around and the hat will follow it but you can still move the hat separately.

ah nice, should i do the same to the shoes?

That answer would really have to be be opinion-based. Personally I'd probably have modelled them as part of the legs, but it depends whether you want to take them off or not! You could of course parent the hat to the head bone of the armature rather than directly to the head, but I'm not sure what would be best for the shoes.


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How to remove all shape keys but exclude one shape key in Script
I have a head model with a lot of shape keys that I don't need. I only need one shape key which is ("mouthOpen"). How can I delete all shape keys excluding the mouthopen ?
I'm a beginner level at python.
This is my attempt:
bpy_obj = bpy.context.active_object

    index = bpy_obj.data.shape_keys.key_blocks.keys()

    for ob in index :
        if index.index('mouthOpen'):
            bpy.ops.object.shape_key_remove(all=False)
        else:
            bpy.ops.object.shape_key_remove(all=True)

Is it a prerequisite for your answer to have python involved? To my knowledge you can archieve this without having to code.

yes, I need to do automation in cleaning up rig model for Readyplayerme avatar :)

In that case I am of no use here. I have 0 coding skills. Sure someone else here knows how. Good luck!

Thanks, man! :)

# make sure you are in object mode first
import bpy

ojs = bpy.data.objects
oj = ojs["Cube"]
bpy.context.view_layer.objects.active = oj #set context.object

blocks = oj.data.shape_keys.key_blocks
for ind in reversed(range(len(blocks))):
    bl = blocks[ind]
    if bl.name in {"mouthOpen", "Basis"}:
        print(f"Key: {bl.name}")
    else:
        print(f"Key: {bl.name} (removed)")
        # set active index before remove
        oj.active_shape_key_index = ind
        bpy.ops.object.shape_key_remove()

appreciate it! I've tried it but I don't know why it always deletes all and leaves the bottom shape key. And I realize I also need the Basis shape key and  not only the "mouthOpen".
I'm have to modify my question to delete all shape keys and leave the basis and the mouthOpen shape key.

if b.name == "mouthOpen":    change to     If b.name in {"mouthOpen", "basis"}:

Hi, I've tried it again but it still removes all shape keys and leaves only the last bottom. I was thinking what if I achieve it by removing from index 2 - 50 because the basis and the mouthOpen is index 0 and 1. How to add
_shape_key_index  to the shape_key_remove

Try the new one, it should work.

thank you!! that's sick! you reverse the range and set the active index..woww I have so much to learn !!


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How to rotate textures? Or how to set texture coordinates?
I'm currently trying to texture a road with textures from CC0Textures. I've got an asphalt texture and a road lines texture both Principled BDSF with their own colour, roughness and normal maps. The only problem is, is that the road lines come out facing the wrong way.

My node setup looks like this.

https://docs.blender.org/manual/en/latest/render/cycles/nodes/types/vector/mapping.html

Hey, I've tried this but all it does is just make it disappear. Though I don't exactly know how to use it :/

You have to plug a texture coordinate node in its vector input.
https://docs.blender.org/manual/en/latest/render/cycles/nodes/types/input/texture_coordinate.html

You can use "Mapping" node: with this node you can edit scale, location and rotation of your texture. Just add it to the node tree of your shader and connect the "Vector" output to the "Vector" socket of your image nodes (try only mask first, and if it doesn't work try with both mask and color/rgh/nrm maps). "Mapping" node needs the "Texture coordinate" node (Shift+A > Input > Texture coordinate).
But I would suggest to properly UV unwrap your plane, so the direction is set in the UV editor once:


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Can't get my texture to show up in 3D view
I can make blender 2.79 sit up and beg but I'm coming up to speed on 2.91 and the learning curve is... significant. Today's problem:
I have a model with a UV diffuse texture and I can't get the texture to show up in 3D view. It's just black.

3D view is showing materials, render pass "Diffuse Color". This is working for other meshes in scene.
Mesh has a "Principled BDSF" shader with "CGX" and "Christiansen/Burley"
Shader has my texture as the base color
Texture file shows correctly in the UV editor. UV shows up correctly in Edit mode.
Switching the texture to one which is showing up correctly on another mesh has no effect. This mesh still shows up as black.

I've checked the shader in the materials panel and also in the shader editor. It looks right, and it looks the same as the other meshes that are working.
Texture does show if I switch the 3D view to "render" but that's slow and I have another problem which I think this problem is causing, so I have to solve it. (When I bake the texture from this model to another, it shows up black.)
I've run out of things to try. Any ideas?
Screenshot showing the model selected, some other models in the same scene showing correctly, the image that should be shown, and the materials panel.

please show a screenshot

Hey :). So the mesh shows any texture as black, but only in Eevee (material preview)?

Screenshot. Shows model selected in 3d view along with two other meshes which are showing correctly. Shows texture in upper right and material in lower right.

Erm, screenshot coming as soon as I figure out how.

I think I'm using cycles, not eevee. But, noob here. Is material preview always eevee? Then that's what I'm using.

please show the Shader Editor so that we can see the node organization (and put the screenshot in your initial question)

Done, @moonboots

You specified your material output as Cycles - try changing it to All.

That did it. Based on the above comments, I think I even understand why. Thank you.

Fixing the material output to match what the 3D layer is using per above suggestion fixed the problem.
The image of the Shader Editor above shows that the Material Output node is set to Cycles. But Blender has several render engines, Cycles and Eevee in particular.
In the image of the 3D View above, the view is set to show Materials. (Circle highlighted in blue in the lower right corner). The materials view uses the EEVEE renderer.
So the key is the material output has to match the active renderer in the 3D view. All or *EEVEE * in the Material Output produce an EEVEE output the renderer can use. Cycles, which I had set for no good reason, does not.

In hopes this can help not just you but also people finding this thread in future, here's some things to check to better understand the problem:

disconnect the image texture from the shader and manually set the base color to see if it's a texture issue at all (in OP's case it isn't)
change the background color (World Properties tab ) to see if the issue is black color of the model or transparency:

As for the solutions:

in viewport shading settings try deselecting Scene World or selecting Scene Lights:

in Material Properties tab make sure Blending Mode is Opaque:

in Shader Editor make sure the Material Output is set to All:

I had the same problem and worked it out by disabling Screen Space Refraction

Hi, thanks for the post. This site is not a regular forum, answers should be substantial, stand on their own, and thoroughly explain the solution and procedure. One liners and short tips rarely make for a good answer. If you can [edit] your post and provide some more details about the workflow and how it works, feel free to restore it, otherwise it may be converted to a comment. Perhaps add a few images illustrating some steps and final result. See How to write a good answer?


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Blender camera with follow-path constraint does weird turns along curve
I have imported a 3D curve into Blender. It was obj and is now NURBS.
All the curve points' tilt values are set to 0.
I have created a camera with an empty parent object.
Then, attached a follow-path constraint to the empty object.
The empty object is attached to the curve and is moving along the curve, however, it does weird turns in random directions along the way making it impossible for the camera to have a proper view of the model.
So tweaking the follow-path parameters won't do the trick.
I know I can manually set tilt values for the curve points but it will take ages.
I was wondering if there's a systematic fix so I could have a neat follow-up along the curve.
Update:
I decided to remove the images and upload a link to the file.
The file contains:

The curve
Suzanne (with an Array + Curve modifier) which clearly shows the weird behaviour.
A camera (Alt+R and Alt+G-ed!)

Changing the follow-up parameters won't fix the overall issue. Cheers

Just turn off "follow curve" in the constraint and it will no longer follow the curve's tilt.  If you want it to track a particular point, give it an additional constraint to do so (track to, damped track, locked track, whatever you want.)

I have the same issue applying an Array modifier. Still think there's sth wrong with the curve. @Nathan

The trick is to select the curve then in Object data properties change the Twist Method from Minimal to Z-Up (screenshot). Thanks to Christopher Bennet for posting the response here.

Path-following Camera -

Use a cube, either visible or invisible as the path object.
Add a line between two diagonally opposed corner vertices and subdivide that.
Set the cube's Origin point to that. (with SH-S)  (Shouldn't be necessary, but... )
Parent the camera to that vertice ONLY.  Select the cube, then the camera, go into Edit mode and select the center vertice.
Press CTL-P --> 'Single Vertice' .
That will stop the cube's tilts & rotation antics from affecting the camera.
The cam can also be turned and animated at will, or focus on some object or other using the 'Track-to' constraint.

Thanks for all the detail. As you mentioned, the centre of the cube is the origin by default. So no need to do that. But I also have issues trying to add an Array modifier to the curve. I am gonna update the post and add a link to the file I have. Just to make sure we are on the same page you know.

I'm on Vers 2.77 here and can't see your file so I'll hand you over to someone else.  Good luck with the curve problem...


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complex geometry bending in wind while maintaining length and individual dimensions (geometry nodes)
I'm working on a scene which includes a grass field that is affected by a strong wind.
Therefore the desired result is a bending affect in the grass, due to the wind force.
For the grass I'm using a grass clump from an asset library.
I have seen posts in the forum that tried something similar with a simple bezier curve as the geometry which is supposed to be affected by the wind. Unfortuantely I failed to apply there solution to a more complexe geometry. Therefore I'm asking here in a new post for help.
In the following, there is my current geo node setup and the results it is generating. The two main problems for me are the distortion (increased width) that is happening on some of the leaves and the stretching of the length of the leaves.

can you share the file to play with?

I added the blend.file to the question. thank u for the interest

See this: Grass wind bending with simulation nodes and maintaining length and then convert the curves to mesh, using either a "Curve Line" profile for flat blades, or something else like a "curve circle" for circular blades (or just 3 vertices of the 'circle' for a triangular profile, you can pass it through a transform to flatten it on one side a little bit etc.) - I don't think it's a reasonable approach to deform the entire mesh.

Yes, it‘s the post I‘m referring to in my text. And I know it‘s possible to expand the approach shown there to make it more grass-like. Me, I‘m interested in finding a method I can apply on a number of different nature assets (more complex plants, trees). So it‘s possible to create a wind effect for complex nature scenes, without having to create all of it inside geometry nodes.

Has anyone any other leads on how to solve the problem? Would be super thankful!!

It seems you want to (basically) reproduce the cloth simulation in geometry nodes. Can be done, and the system used in Blender is open sourced, you can read the implementation - you probably would be satisfied with some simplifications, but thinking about it, I think it would still turn out to be too complex for me to bother to write it into an answer: grass alone will need to interact with gravity, have its stiffness, that's an interaction based on edges, you also probably want to maintain volume… This could easily turn out to be the most complex answer I've ever written…


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Blender 2.92 Lag when modeling
Computer Info:
CPU - Intel i9 10900K
GPU - 3090 Geforce
Memory - 32GB
Windows 10
I have been working on different models, some have a lot of vertices others don't. Most do have subsurf at 4 or 5 but so did many other models I did prior and I wasn't getting this problem. I will move an item or scale a section of vertices and it will jump like a second later. This started recently and I am not sure what has happened since then. I actually installed a new CPU and motherboard thinking that was the problem and it didn't help. When it is at the worst my memory usage is at 30%. I recently have installed Windows and have a fresh install of Blender and it is still doing this. I have been looking at other posts on this issue which are usually 2.8 and prior versions of Blender. Nothing on those seem to fix it or are relevant. Any help would be greatly appreciated.
Update: This morning I was working on a model that had 900 vertices and it kept on lagging when I tried to apply a bevel. Also it lagged when I tried to apply a seam(shift-E) or clear a seam.

"subsurf at 4 or 5" seems a lot also for a powerful computer.

can you check if the falloff of the brush is set as sphere and not "projected"?

Yes it is set to sphere

So still have a problem here and there but just now I was trying to vertex paint on a model with about 100 to 200 vertices. It was taking forever to paint the object still working on it.


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How export constant keys?
I have recorder cutscene where the characters and the camera are teleported depending on the camera frame using constant keys.
When exporting to unity, the keys become linear and the movement between teleportation becomes noticeable, how do I solve this? (Simplify doesn't help)
To reproduce the problem, you need to record the constant key, export fbx, import it, and it will become linear (in the span of one frame).

baked :

If when exporting your asset you let the bake animation enabled and the sampling rate on 1, then it should put keys on each frame of your animations, removing any interpolation and negating the effects of key type change.
I forgot to mention, Blender's FBX exporter does a keyframe cleanup in its baking, which you might want to remove by setting the "simplify" to 0.

It always export linear keyframes, i need contant

You won't export constant keyframes, hence the baking. If you bake the animation on export, it will place keyframes everywhere needed so that you don't leave any of your animation to hazardous interpolations and incompatible data transfers. Plus in videogame you want your animations to be baked so you don't use extra resources calculating unnecessary interpolations, it's faster to have as much keyframes as you can bear. I forgot to mention, Blender's FBX exporter does a keyframe cleanup in its baking, which you might want to remove by setting the "simplify" to 0.

I cant export fbx animation without baking. So its impossible?

You can't export any other keyframe type but linear. You have to bake if you have animation data that can't be done using only linear (which is basically every animation in the world) and you have to bake for performance and data reliability anyway. So, just always bake, out of principle.

So, how can i make teleports in cutscene like this?
https://www.youtube.com/watch?v=OXW5Z1fmlb0
Unity shows the movement between frames well, do I need to limit the frames in unity or increase them in blender?

Have you baked your animation with the settings I advised you?

yep, still can notice movement in unity between blender frames

Then post your files he so we can check this. It's not normal.


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how do you bevel like shown in picture

what i have tried

insetting but insetting starts tearing the faces after some thickness
i tried beveling but i do not have idea how do i do varying bevel as shown in the picture

edit:

the face tearing is marked in red
I want to inset the face and modify it along the blue lines (how do I do this?)
the bevel thickeness of inset is 3cm in thickness

Proportional editing might be helpful here.

If you have still problems it might be a good idea to add a screenshot of what you have done so far. It's not clear to me where you want to bevel it honestly.

i have added a picture, please check it out

There are many options. Use a Curve and parent it to faces, modify in Editmode and extrude with curvemodifier.
Or use Subdivision surface modifier and bevel it out, after mesh and scale a cube with 4 Faces. (Delete front/backface)

I'm new to blender, could you be a bit more clear (a small gif would be of great help)

@arjunlokesh : don‘t worry. I have a bit experience in Blender and I don’t understand it either…


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camera animation - camera following path with offset
the camera has a weird offset from the path i want to follow. the origin of the camera has a blue dotted line to a weird place in the curve which i feel is the reason for offset. I shall show how i do the animation.
video of how i set animation

the weird offset is highlighted in red and the blue shows how i want the camera to follow the path
moonboots solution worked in getting the camera to the position.
the al + g actually solved the issue however the camera has the blue line going somewhere in the world and when i change the offset from 616 to 522 it doesnt happen to be following the curve i just made.

Select the camera and press Alt G so that it sticks to the curve, does it fix the problem?

yes thanks! may i know why this is happening ?

you need to reset the camera location, Alt G, so that it sticks to the first vertx of the curve, otherwise Blender thinks that you want to offset its location

Select the camera and reset its location with AltG so that it sticks to the curve first vertex, otherwise you'll have an offset.

i did do that and it solved the issue however the camera has the blue line going somewhere in the world and when i change the offset from 616 to 522 it doesnt happen to be following the curve i just made.

i found the solution to my weird problem . apparently its important that the offset constraint of the camera is set to 0 before doing the alt + G.


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rendered image has jaggedered edges
I am trying to render the image of a jersey. The jersey looks decent.

however when i render it there are lots of issue with jaggered edges and somehow bad render...?

I added sub division surface modifier but it doesnt seem to be solving the issue.

the file can be found here
drive link to the file

hello, maybe the image is simply too low res?

its 1920 x 1920

It's the model that is too low res, not the image. I think if you are not happy about the model, you should either remodel it(simulate it in higher resolution) or attempt to fix it - maybe sculpting after subdividing could help. This does not seem to have anything to do with rendering. It's about the geometry that is being rendered.


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area light lighting unevenly in a scene evee
i am trying to light a symmetrical box in a scene as background however the area light lighting it unevenly (over lit on right)

On the left it behaves as the way expected however on the right it over lights the scene

Hello could you please share your file, I can't reproduce the same problem with an area light

Maybe try setting the scale to 1, ans set Shape to Rectangle ? I'm not sure if that could be the issue.

https://drive.google.com/file/d/1sNfDuwxu76os0P_fC9uB3UbPV5Sp6Iwt/view?usp=sharing - the file is here

You forgot to include your image textures in your blend file, so it's hard to tell for 100% certainty. But shader normals can definitely give such results, and you can see yourself that unplugging the normal map node from the Principled BSDF "fixes" the issue.
First, make sure you have a valid normal map, and whether it is object or tangent space:

Credit: glsl - How To Convert World Space Normal To Tangent Space? - Game Development Stack Exchange

Your image textures nodes for roughness and normal have their color management set to sRGB. The only kind of maps that should be left with that are ones that directly affect color, such as base color / albedo maps or emission. Other ones should be set to non-color for Blender to interpret them correctly. And in the case of a normal map, it could be the cause of your specific issue.
So try to set your rough and normal image textures to non-color color management, and it probably will fix the issue:

And seeing the name mentions "dx", maybe you have a DirectX format normal map, which need to have its Y channel inverted in Blender who is based on OpenGL. It's a bit had to tell if you don't know the shape supposed to be represented. When looking a normal from top to bottom, OpenGL uses green (Y) to show upward slopes and purple for downwards slopes.

Credit: cycles render engine - DirectX vs. OpenGL normal maps - Blender Stack Exchange

Or look at the final surface, moving a light around it to see if bumps look like bumps and holes like holes. If not, cycles render engine - DirectX vs. OpenGL normal maps - Blender Stack Exchange


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Blender render result not consistent

This is a one-color green cube rendered, no light in scene.
But it has two color mixed instead(try color pick).
Anyway to fix this?
Here is the shader I used for cube.

In your Render Properties tab, scroll all the way to the bottom where it says "Color Management" and under View Transform try changing from "filmic" to "standard" and see if that helps. It's hard to tell much else without seeing your node setup, any chance you could post a screenshot?

I suspect it may have something to do with dithering, i.e. Blender tries to display color that can't be described in a given color space, so, based on some formula involving position, it displays one of neighboring colors in the color space. Can you go to Output Properties tab, expand Post Processing panel on the very bottom and decrease dithering to 0?

I changed view transform to raw and standard, still has two colors.

Thanks a lot Broady, my problem solved!

Dithering is useful, so it's still worth to investigate why Blender fails to display the exact color and dithers it.


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Move an object after baking normals
I'm a new Blender user and I'm facing my first big issue.
I've just baked high poly normals to a low poly object successfully after a night of tutorials reading, but now, whenever I try to move the low poly object, normals won't follow the low poly object in space.
What should i do if i need to move any object that i've baked avoiding this issue ?
https://i.sstatic.net/3sKxS.jpg here is my node setting
https://i.sstatic.net/MRpyc.jpg here is what happens whenever i try to move the low poly object affected by the baked normals
Did I miss something during the baking or anything ? I've noticed whenever I disconnect the normal node, the normals stays active but nothing changes and I'm still not able to move it without this awful result.

hello, please show your node setup, you need to use the Texture Coordinate "UV" output socket

I've found the issue and I feel stupid now but maybe someone will feel like me one day so here is what happened : Before I bake normals, I add a modifier on my low poly (shrinkwrap) and I forgot to shut it down... :p


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Low Poly Character Elbow Deforming
I made a low poly character that I am rigging currently.  However, when I bend the elbows inward on the Z-axis, the inner part of the elbow bends too much (Picture attached).

I have tried doing shape keys however I have the mirror modifier enabled so that wont work as the key effects both sides.

I have tried changing the weights but haven't found the right numbers.

** On the elbow there are 8 vertices that make it up, 4 on the outer part, and 4 on the inner part **
File: https://drive.google.com/file/d/13RwzuTDdQ_MhGH_Z18uQ_l7vIP_pelpN/view?usp=sharing

please share your file. If shapekey doesn't work you could create one or 2 bones for the elbow so that it will deform it?

I have added a link to the file.
Hm.  I think I saw someone talk about that.   So you think adding a bone in the elbow would help?

why not but why don't you want to apply the Mirror?

if you create an elbow bone that influence the inner side of the elbow, you can use it to deform the mesh when the arm is bent, but it means either move this elbow bone after rotating the arm or give it a driver

@moonboots I guess I could.  The only thing I didnt know is if I need to change the mesh for any reason, will reapplying the mirror still work?

you can use the Mesh > Symmetrize or Snap to Symmetry to symmetrize back but you'll have to bring correction in Weight Paint mode

@moonboots Couldnt I just reapply the mirror after I do the shape keys?

you can't apply a mirror if you ceate shapekeys

@moonbootsI see. What I ended up doing was the shape key which seems to be fine for now.  Ill just have to make sure I change each side the same which shouldn't be too bad. Thanks for the help!


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Render shadows without denoise on a transparent background in cycles
I have a problem with the graininess that appears in the shade. I want to render an object with a nice and clean shadow. The result is a png with a transparent background.
Render in Cycles engine. I have enabled Shadow Catcher, Transition, RGBA, Denoising - OpenImageDenoise . The number of Samples is 1000.
Can I fix this problem somehow?

Does this answer your question? Shadow-catcher stays noisy even with Denoising - also very dark

One way to solve this problem is to render the shadow catcher in a separate view layer. Then, in the compositor, add a blur node for this view layer, then alpha over the other layer. C.f. linked question.

I was dealing with the same issue in a very similar scenario, I bumped up the samples to 2500 and used NLM denoise.
I tried many other tricks and variations but to this date, couldn't find a better solution other than just using more samples.

This may not be ideal, but I solve this issue by passing the "Alpha" from "Render Layers" through a HDR Denoiser, then use the denoised alpha map to blend with the background image to generate the noise free shadow.

Hi, thanks for help but it still doesn't work. I created nodes in compositor: https://ibb.co/xq72WgV  , but result is still same


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Problem with Child Of Location
I'm learning Blender and am following a spiderman tutorial ( https://youtu.be/UO0OM0plOX0?t=773 ) .. but I've been battling a serious problem for several days now and can't find the solution. Maybe someone can help ? I use Blender 2.92 and when I insert the Keyframe when letting go of the Web at around 13:00 it actually puts the (ChildOf-)Empty to the starting position and not to the current position? So My "web" just snaps around weirdly and does not at all behave as it should.. (when I observe the Empty's location coordinates the don't move at all either, but the empty moves, beeing linked to the hand)..
https://youtu.be/UO0OM0plOX0?t=773
Here 3 pics of the problem :
Here pic 1, start of animation "Empty" is selected Location is shown :
Then 1st Keyframe :  (Location unchanged)
Then the frame right afterwards where the Empty snaps back to original location :

Can you put screenshots instead of requiring following the YouTube link?

Yes of course, sorry.
Here pic 1, start of animation "Empty" is selected Location is shown : https://pasteall.org/media/b/0/b01f3c51bc306157bc0015d1f80a0b02.png
Then 1st Keyframe : https://pasteall.org/media/3/e/3efe87d74a985b3c992f031dd414ab31.png 5Location unchanged)
Then the frame right afterwards where the Empty snaps back to original location :
https://pasteall.org/media/2/3/23f907c9052a0340ea2f6c72566d717e.png

Can you edit them into the question?

Did it right away, sorry, new to StackExchange..

Ok, that’s good formatting. Hmm, the child of constraint would not be adequate to leave the empty in the correct position... maybe it’s backwards, or you forgot to animate something?

Have a look at 'Method 2' at the link below.  I think @Moonboots came up with this and it sounds like it could solve your problem.  I'll have to spend time and find the original post for future reference when I have time.  To repeat myself, "Method 2". The link -
https://blender.stackexchange.com/questions/154199/how-to-sequence-paths/154777#154777

Cont from above...  Follow 'Method 2's instructions down to the line - "You can now move the timeline. The model is again free and unconstrained".  If you run into trouble there is another option - bake the model's action.  That will free it of all constraints when you tick all the Baking panel's boxes.  A 3rd option is to split the action between two Blend files.  More details available if you need them.


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Render parts of object(s) only when they are within a defined area
I'd like to animate a train car entering and exiting a diorama from left to right. As the train car exits the station, "breaking the plane" that is the boundary of the station, the parts of the train car outside the station should be transparent.
Here's what the train car would look like passing through if there were no masking or holdouts or anything:

What I'd like is for it to be "chopped off" outside the diorama bounding box, resulting in something like this:

...but I don't want to accomplish this with booleans. It's way too expensive and intense, as the train will have many objects and shaders involved with it.
I can achieve the desired effect behind the station with compositing and render layers using holdouts. But the foreground part of the train as it exits, I'm lost on how to achieve that.
Thanks!

With Holdout:

Create a layer with the train and with a holdout object both visible (make sure that the holdout object is alpha blend and no shadow):

Create a second layer with neither of these 2 objects visible:

Render and mix in the Compositor through a Color > Alpha Over:

Or create a black and white image that will allow you to mask the left part:

Create 2 layers, one with the train, one without, use the black and white image as a mask in the Compositor:

That's really simple and brilliant - thanks!


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The second Particles System not working Properly
I am building up a firework scene after watching this tutorial. However, some problem turns up when I set up the second Particle System. In the tutorial, the second particles emission from the first ones. But when I tried it out, it is not so. My second particles was a line of cubes(at the cursor of the picture). I changed a lot of setting, but it never works like in the tutorial.

Blender version:2.77a
OS System:UbuntuStudio
My blender file is uploaded to GDrive, Download it if you need it.
Don't care about the stuffs in the first layer;)

I can't sift through it right now, but this other tutorial looks like it's doing the same thing, but with a newer version of Blender. See if this one reveals what the problem is... https://www.youtube.com/watch?v=s9vceDdTufo

@Matt  But in this tutorial it set three particle systems--same as the video I watched.

@Matt in the video above at about 11:18, after he settled the third particles, when he play the animation, a line of stuffs drop off just like mine, but there are small stuffs come behind the first particle system. Can the phenomenon be explained?

There should be 2 particle systems on the object (there's only one in your file). The second particle system modifier should be in the bottom of the stack.

You will setup it as desired, the main option to change would be start and end frame.
Starting frame should be roughly the same as the end frame of the first system. Values from the lesson didn't work well so I changed them - while particles of first system die at frame 26, particles of the second one burn at 23.
However to make second particle system emit particles from the faces exploded by the Explode modifier you should enable Use Modifier Stack option:

The reason this wasn't mentioned in tutorial is because Use Modifier Stack option was added starting from version 2.68.


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Resize different sized faces to 1 uniform size?
I would like to be able to select a group of faces that are all different sizes, and be able to make them all the same size.
Please see the attached image for the my example -

I would like to resize all the highlighted faces to be 1 uniform size (ie. the average size) so that I can then extrude them back to create equal sized indents.
The method needs to resize them based on their current orientation as the surface is not completely flat (intentionally).
Thanks in advance.

Partially related - http://blender.stackexchange.com/questions/7698/how-to-evenly-space-vertices. You select bottom edges of faces and execute Looptools > Space. Length of selected edges will become roughly the same. Then you should repeat that with other edges forming the faces.

I'm affraid it is impossible to do this in one step. I'll show you the dirty way.
With the face select mode enabled select the face and press Shift+Num 7 to allign it to view. Then snap the cursor to it (Shift+S-->Cursor to Selected) and add a plane. Check the Allign to View box in a Tool Shelf (T) and scale it (S) to the desired size.

Enable the snapping tool (click the magnet icon), change snap element type to Vertex. Snap the vertices of your object to the newly added plane, then select the whole mesh (A) and remove doubles (W-->Remove Doubles).

Repeat the process with the other faces.

You could use Smooth and repeat W -> Smooth -> F6 and adjust Smoothing factor and number of Repeats.
Or a small script - at the end of the script all selected faces will have almost identical area. The orientation and shape are preserved.
import bpy
import bmesh
import math
from math import sqrt

obj = bpy.context.edit_object
me = obj.data
bm = bmesh.from_edit_mesh(me)

face_data = []
area_accum = 0.0
for f in bm.faces:
    if f.select:
        area = f.calc_area()
        if area != 0.0:  # avoid divide by zero
            center = f.calc_center_median_weighted()
            face_data.append((f, area, center))
            area_accum += area

            print(area)

area_average = area_accum / len(face_data)
print("average area is:", area_average)

for f, area, center in face_data:
    rescale = sqrt(area_average / area)
    for l in f.loops:
        v = l.vert
        v.co = ((v.co - center) * rescale) + center

bmesh.update_edit_mesh(me, True)

output:
0.009626750834286213
0.01746169477701187
0.020414138212800026
0.009531363844871521
0.012785278260707855
0.016477763652801514
0.010115167126059532
average_area 0.013773165244076933

# if you ran it a second time all areas are as close as they'll get.
0.013773156329989433
0.013773160986602306
0.013773168437182903
0.013773171231150627
0.01377316378057003
0.013773173093795776
0.013773162849247456

(view this image in a new tab to see the difference in area directly displayed on the polygons)

The above script preserves Shape, but uses a rescale factor to homogenize the Area of all selected Faces. If you need to also make all edge lengths the same while preserving Area and Orientation that's possible too.


text:
Lining up vertices/edges horizontally along a slanted object without altering the shape of the object?
I have a slanted object with verts aligned along the slanted edge, however I wish to have the verts aligned horizontally (in Global orientation) while still maintaining their alignment with the edge they are placed on.

If I S, Z, 0, this gets them all perfectly in line, but then it changes the shape of object as it pulls all the verts in a bit.
If I set the edge as the transform orientation, and use snapping to align the verts, then it aligns them as they are currently are in the screenshot.
In essence, I need to mix the 2 methods to align in Global orientation while maintaining the edge alignment.
Any help would be appreciated.
Thanks

Related: http://blender.stackexchange.com/questions/29043/slanted-loop-cuts and http://blender.stackexchange.com/questions/14481/how-do-you-make-a-loop-cut-a-straight-line-not-follow-the-contours-of-the-mesh

The best option here IMO is to use a knife tool. Press K and place the knife icon on the vertex to snap to it. Then press C to make a straight cut. Then select the angled edge and press X-->Dissolve Edges.

To align other edge loops to the newly created horizontal one add an edge loop with Ctrl+R, press E and then F.