// from OGRE3D's skinningTwoWeightsShadowCasterVp.glsl
// Example GLSL program for skinning with two bone weights per vertex
attribute vec4 vertex;
attribute vec4 uv0;
attribute vec4 blendIndices;
attribute vec4 blendWeights;
// 3x4 matrix, passed as vec4's for compatibility with GL 2.0
// GL 2.0 supports 3x4 matrices
// Support 24 bones ie 24*3, but use 72 since our parser can pick that out for sizing
uniform vec4 worldMatrix3x4Array[72];
uniform mat4 viewProjectionMatrix;
uniform vec4 ambient;
void main()
{
vec3 blendPos = vec3(0,0,0);
for (int bone = 0; bone < 2; ++bone)
{
// perform matrix multiplication manually since no 3x4 matrices
// ATI GLSL compiler can't handle indexing an array within an array so calculate the inner index first
int idx = int(blendIndices[bone]) * 3;
// ATI GLSL compiler can't handle unrolling the loop so do it manually
// ATI GLSL has better performance when mat4 is used rather than using individual dot product
// There is a bug in ATI mat4 constructor (Cat 7.2) when indexed uniform array elements are used as vec4 parameter so manually assign
mat4 worldMatrix;
worldMatrix[0] = worldMatrix3x4Array[idx];
worldMatrix[1] = worldMatrix3x4Array[idx + 1];
worldMatrix[2] = worldMatrix3x4Array[idx + 2];
worldMatrix[3] = vec4(0);
// now weight this into final
blendPos += (vertex * worldMatrix).xyz * blendWeights[bone];
}
// apply view / projection to position
gl_Position = viewProjectionMatrix * vec4(blendPos, 1);
gl_FrontSecondaryColor = vec4(0,0,0,0);
gl_FrontColor = ambient;
gl_TexCoord[0] = uv0;
}