source: data/branches/Shader_HS18/programs/GLSL/instancingVp.glsl

uniform vec4 worldMatrix3x4Array[240];
uniform mat4 viewProjectionMatrix;
uniform vec4 lightPos;
uniform vec4 ambient;
uniform vec4 lightDiffuseColour;

void main()
{

        // transform by indexed matrix
        // perform matrix multiplication manually since no 3x4 matrices
        vec3 transformedPos;
        vec3 transformedNorm;
        int instanceOffset = int(gl_MultiTexCoord1.x) * 3;
        for (int row = 0; row < 3; ++row)
        {
                vec4 matrixRow = worldMatrix3x4Array[instanceOffset + row];
                transformedPos[row] = dot(matrixRow, gl_Vertex);
#if SHADOW_CASTER
#else
                transformedNorm[row] = dot(matrixRow.xyz, gl_Normal);
#endif
                
        }
        
        // view / projection
        gl_Position = viewProjectionMatrix * vec4(transformedPos,1);
        gl_TexCoord[0] = gl_MultiTexCoord0;
    gl_FrontSecondaryColor = vec4(0);
        
#if SHADOW_CASTER
        gl_FrontColor = ambient;
#else
        vec3 lightDir = normalize(
                lightPos.xyz -  (transformedPos.xyz * lightPos.w));
        gl_FrontColor = ambient + clamp(dot(lightDir, transformedNorm),0.0,1.0) * lightDiffuseColour;
#endif
        
}