Original Post
I am doing GPU skinning in my vertex shader which works fine on PC, and which I'm porting to Android. My vertex shader is below, and the problem is that the creation of the matTransform matrix seems to only use the first matrix in boneMatrices:
#version 300 es
precision highp float;
precision highp int;
//Uniform count: projectionMatrix(16) + modelViewMatrix(16) + MVPMatrix(16) + textureMatrix(16) + normalMatrix(9) + lightMVPMatrices(16*5) + nShadowLights(1) + boneMatrices(16*boneMax) = 73 + 1 + 16*shadowLightMax + 16*boneMax = (out of ~1024 components)
//GLSL ES (vectors): projectionMatrix(4) + modelViewMatrix(4) + MVPMatrix(4) + textureMatrix(4) + normalMatrix(3) + lightMVPMatrices(4*5) + nShadowLights(1) + boneMatrices(4*boneMax) = 19 + 4*shadowLightMax + 4*boneMax = 239 out of 256 vectors on Nexus 5 (shadowLightMax = 5, boneMax = 50, 17 vec4s remain, or 4 matrices and 1 vec4)
//Matrices
//uniform mat4 projectionMatrix;
uniform mat4 modelViewMatrix;
uniform mat4 MVPMatrix;
uniform mat4 textureMatrix;
uniform mat3 normalMatrix;
uniform mat4 lightMVPMatrices[5];
uniform int nShadowLights;
//Bones
uniform mat4 boneMatrices[50];
//Vertex information
in vec3 position;
in vec4 colour;
in vec2 texCoord;
in vec3 normal;
in vec3 boneWeights;
in ivec4 boneIndices;
out vec4 _colour;
out vec2 _texCoord;
out vec3 _normal;
out vec3 _eyePos;
out vec4 _lightPos[5];
void main(void)
{
vec4 positionSkinned;
vec4 normalSkinned;
mat4 matTransform = boneMatrices[boneIndices[0]] * boneWeights[0];
matTransform += boneMatrices[boneIndices[1]] * boneWeights[1];
matTransform += boneMatrices[boneIndices[2]] * boneWeights[2];
float finalWeight = 1.0 - (boneWeights[0] + boneWeights[1] + boneWeights[2]);
matTransform += boneMatrices[boneIndices[3]] * finalWeight;
positionSkinned = matTransform * vec4(position, 1.0);
//positionSkinned.w = 1.0;
normalSkinned = matTransform * vec4(normal, 0.0);
gl_Position = MVPMatrix * positionSkinned;
_colour = colour;
_texCoord = (textureMatrix * vec4(texCoord, 0.0, 1.0)).xy;
_normal = normalize(normalMatrix * normalize(normalSkinned.xyz));
_eyePos = (modelViewMatrix * positionSkinned).xyz;
for(int i = 0; i < nShadowLights; i++)
_lightPos[i] = lightMVPMatrices[i] * positionSkinned;
}I have verified that:
1) the correct matrices get pushed into boneMatrices
2) the correct bone indexes exist within boneIndices
3) the correct boneWeights exist within boneWeights
4) accessing components of boneIndices with dot notation (.x, .y, .z and .w) doesn't make a different
5) There are no OpenGL errors at all, as I check for errors after every call, and uniform size isn't an issue (if I increase boneMatrices by 5 extra matrices, I get invalid operation errors after each time I push matrices to the shader, but at this size and lower it's fine)
I have checked points 1, 2 and 3 (boneMatrices, boneIndices and boneWeights are correct) by doing the following:
1) using a specific animation which modified a few bones only (e.g. boneMatrix[6]), then hard-coding boneMatrix[6] and verifying that all vertices get properly modified by this single matrix, with the same result on PC and Android
2) drawing out boneIndices by doing the following in the vertex shader:
_colour = vec4(float(boneIndices[0]), float(boneIndices[1]), float(boneIndices[2]), float(boneIndices[3]));and the following in the fragment shader:
gl_FragColor = _colourwith the same colours on PC and Android
3) doing the same as above but with setting _colour to:
_colour = vec4(boneWeights[0], boneWeights[1], boneWeights[2], finalWeight);I have no idea what else to try, and it definitely seems to be that only the first matrix is used. I have also tried using vec4 instead of ivec4 for boneIndices. This is on a Nexus 5 with an OpenGL ES 3.0 context. Help!
Here are images from it running both on Windows (showing all bone matrices being used) and on Android (showing only the first being used) with bones indices used for colour.
