Blender Animations inverting mesh normals

[amorgan]

I have imported my mesh with a skeleton and animation. The Mesh comes in correctly, but once I play the animation all of the normals get inverted? I am using v2.0 beta (just downloaded fresh)? It is the same model here: http://www.html5gamedevs.com/topic/12002-blender-and-animations/

 

Any ideas?

[gryff]

Very odd behaviour amorgan

 

I have created two examples to show the effect so the coders can see the effect:

 

1. Animation not allowed to play

 

2. Animation allowed to play once

 

The babylon file created with Blender 2.73 with the babylon exporter 1.62

 

cheers, gryff

[amorgan]

Has anyone had a moment to take a look at this? I am not sure if this is a Bablyon issue or a Blender issue, though I don't know what the issue could be if it originates from Blender.

 

Thank you.

[gryff]

The above two examples are done with babylon.2.0-beta.js (downloaded last Saturday - Jan 24th 2015 - from github)

 

This is the same babylon file used in the above two examples but using babylon.1.14.js

 

3. Animation Playing

 

It seems to work fine

 

I am not sure if this is a Bablyon issue or a Blender issue

 

Well amorgan, to me there seem to be two options:

 

a.) There is an issue with the exporter - which seems unlikely as the file behaves the way it should with babylon v1.14.

 

b.) There is an issue with babylon 2 .

 

Be nice if a babylon coder took a look at this thread.

 

cheers, gryff

[Dad72]

Sorry, I do not use blender. but if it works with 1.14 and it does not work with 2.0 it is actually possible that this is a problem that version 2.0.

[JCPalmer]

I am also having a problem with bone animation.  The test .blend Gryff made suddenly went weird once animation started.  I thought it was me doing something in exporter.  I have been getting frequent updates to 2.0.  Think it started last Thursday.

 

Did not report, because I thought it was me, but this does seem to fit with an external (to me) change.

[amorgan]

Well makes me feel better, hopefully DK or someone can take a look at this. Thanks for everyone's help so far!

[JCPalmer]

Some more color:

I found a Jan 5, babylon 2.0 on my system.  Replaced my Jan 23 version with it, and it now animates correctly.  Put it back to Jan 23 and problem.  Thought the problem showed up the day before though, Jan 22.

 

Also, not experiencing a normals problem.  See picture

 

[JCPalmer]

Found another on Jan 22, 632.6 kb, a little smaller than the Jan 23 file.  Still have the problem.

 

Using Github, got the file with the tag '/*! Babylon 2015-01-20 */'.  Still the error.  I have not been re-running my entire battery of test with every version I get.  Do not actually care much about bones, since I have not actually been do dev there.

 

Was going to check earlier files, but nothing before that.

[GameMonetize]

Crap!

 

Gryff can you send me the .babylon file you used?

[gryff]

Your wish is my command

 

Figure.zip

 

I hope it is not serious.

 

cheers, gryff

[GameMonetize]

Investigating

[JCPalmer]

Hey,  score a big one for paranoia!  The entire volume backup process I do using truecrypt got me a repository with a babylon.2.0-alpha.js with the date Jan 20.

 

Want me to try to walk back last known working comit?

 

[JCPalmer]

Well, just double checking I could actually do it.  Bisected & tried Jan 11, still worked.  Will check till no longer works.

[JCPalmer]

Jan 19, 2015 1:03:51 PM, Performance improvements is the culprit

[JCPalmer]

classes changed in that release:

Color4.prototype.copyFrom

Quaternion.Identity

Matrix.prototype.decompose

Matrix.Compose

Tools.Sign

Tools.CreateScreenshot

AsyncLoop

_DepthCullingState

 var partialLoad

Engine constructor

Engine.prototype.createCubeTexture

Engine.prototype.createCubeTexture

SpotLight.prototype.getAbsolutePosition

SpotLight.prototype.computeTransformedPosition

DirectionalLight.prototype.getAbsolutePosition

DirectionalLight.prototype.computeTransformedPosition

ShadowGenerator.prototype.isReady

Scene.prototype.getNodeByName

Mesh.prototype.simplify

Particle.prototype.copyTo

ParticleSystem.prototype.recycleParticle

Animation.prototype.matrixInterpolateFunction

Animation.prototype._interpolate

 

Getting tired. More if asked for

[GameMonetize]

Ok thanks JCPalmer, sounds like a good point to start with

[GameMonetize]

ok and it's a win!!

 

The matrixInterpolate stuff introduced by kpko. So far I'll revert the matrix interpolation code to previous version

[kpko]

Hi guys,

 

I'm currently investigating this issue. I had a similar problem while testing with one of my own models exported from Blender, but since the meshes and animations which come with the babylon samples are working with the interpolation functions, I would have not believed the bug was introduced by my code and I did something wrong in Blender itself.

[GameMonetize]

Thanks a lot Kpko!

 

So far I commented the interpolation so things should now work well

[kpko]

Hi again,

 

I think I found a clue leading to the problem. I looked into the file exported by Blender:

...    "skeletons": [        {            "name": "Skeleton",            "id": 0,            "bones": [                {                    "name": "pelvis",                    "index": 0,                    "matrix": [                        1,                        0,                        0,                        0,                        0,                        1,                        0,                        0,                        0,                        0,                        -1,                        0,                        0,                        4,                        -0.1425,                        1                    ],...

If you have no rotation, the scale values of the matrix (the values at position 0 (scale x), 5 (scale y) and 10 (scale z)) would be X: 1, Y: 1 and Z: -1. This could lead to the flipped normals problem. These values are created from the Blender exporter which I'm not very familiar with. 

 

Maybe my code did reveal that issue because I multiply with those matrices when I do the interpolation. I'm still looking into this issue, but could anyone who knows the Blender exporter tell me where the value "-1" is coming from? Just to be sure :-)

 

Thank you very much for flagging this bug :-)

[GameMonetize]

I.m not sure this is related to exporter because rendering works with the same .babylon file so far

[JCPalmer]

Maybe my code did reveal that issue because I multiply with those matrices when I do the interpolation. I'm still looking into this issue, but could anyone who knows the Blender exporter tell me where the value "-1" is coming from? Just to be sure :-)

 

Cannot help you directly.  Code is below.  Matrix_world comes from skeleton.matrix_world.  I did not write this part. 

@staticmethoddef get_matrix(bone, matrix_world):    SystemMatrix = mathutils.Matrix.Scale(-1, 4, mathutils.Vector((0, 0, 1))) * mathutils.Matrix.Rotation(math.radians(-90), 4, 'X')    if (bone.parent):        return (SystemMatrix * matrix_world * bone.parent.matrix).inverted() * (SystemMatrix * matrix_world * bone.matrix)    else:        return SystemMatrix * matrix_world * bone.matrix

I can say that when I first saw this issue, that I diffed my in-line code generated (similar to .babylon file).  I found that Blender 2.72 generated different values for some position, normals, indices, skeleton weight, & skeleton indices than 2.69.  None of the bones matrices or animations changed. This is why I thought it was something I had done in an unreleased version of the exporter.

 

It did not make any sense that it rendered ok without animation, though.  Gave me a head ache & was not in production, so I worked on something else.  Think that 2.72 must of just generated things in a different vertex order.

[kpko]

I.m not sure this is related to exporter because rendering works with the same .babylon file so far

 

Yeah, I'm not sure too, that was just the first thing that caught my attention.. As far as I know, -1 at this position defines a negative scale at z axis, given you have no rotation:

 

https://www.opengl.org/discussion_boards/showthread.php/159215-Is-it-possible-to-extract-rotation-translation-scale-given-a-matrix

 

 

 

To begin, your scale matrix is of the form 

Code :

[sx 0 0 0]

| 0 sy 0 0|

| 0 0 sz 0|

[ 0 0 0 1]

 

which is really difficult to extract when a rotation was applied:

[ ax*ax*(1-c)+c    ax*ay*(1-c)+az*s  ax*az*(1-c)-ay*s   0]|ax*ay*(1-c)-az*s   ay*ay*(1-c)+c    ay*az*(1-c)+ax*s   0||ax*az*(1-c)+ay*s  ay*az*(1-c)-ax*s   az*az*(1-c)+c     0|[       0                 0                 0           1]

[amorgan]

Thanks for being on top of this guys! I tested the newest version with mine and of course it works. I know you guys have more stuff to work on, but thank you!

 

On the note of animations and blender, does the exporter support multiple animations? I have made multiple animations with the Action Manager and have attached them to Fake Users, but are not showing up anywhere in the imported model. I can make another forum post if needed.

 

Edit: Also wanted to note that I now have two meshes that are attached to my bones and only the first mesh is moving with my animation?