source: data/branches/Shader_HS18/programs/GLSL120/skinningTwoWeightsVp.glsl

#version 120
// Example GLSL program for skinning with two bone weights per vertex

attribute vec4 vertex;
attribute vec3 normal;
attribute vec4 uv0;
attribute vec4 blendIndices;
attribute vec4 blendWeights;

// ogre <> glsl notation is transposed
uniform mat4x3 worldMatrix3x4Array[24];
uniform mat4 viewProjectionMatrix;
uniform vec4 lightPos[2];
uniform vec4 lightDiffuseColour[2];
uniform vec4 ambient;
uniform vec4 diffuse;

void main()
{
        vec3 blendPos = vec3(0.0, 0.0, 0.0);
        vec3 blendNorm = vec3(0.0, 0.0, 0.0);

        for (int bone = 0; bone < 2; ++bone)
        {
        // ATI GLSL compiler can't handle indexing an array within an array so calculate the inner index first
                int idx = int(blendIndices[bone]);

                // now weight this into final
                float weight = blendWeights[bone];
                blendPos += worldMatrix3x4Array[idx]* vertex * weight;

                mat3 worldRotMatrix = mat3(worldMatrix3x4Array[idx]);
                blendNorm += (worldRotMatrix * normal) * weight;
        }

        blendNorm = normalize(blendNorm);

        // apply view / projection to position
        gl_Position = viewProjectionMatrix * vec4(blendPos, 1.0);

        // simple vertex lighting model
        vec3 lightDir0 = normalize(
                lightPos[0].xyz -  (blendPos * lightPos[0].w));
        vec3 lightDir1 = normalize(
                lightPos[1].xyz -  (blendPos * lightPos[1].w));

        gl_FrontColor = gl_FrontMaterial.diffuse * (ambient + (clamp(dot(lightDir0, blendNorm), 0.0, 1.0) * lightDiffuseColour[0]) +
                (clamp(dot(lightDir1, blendNorm), 0.0, 1.0) * lightDiffuseColour[1]));

        gl_TexCoord[0] = uv0;
}