source: data/branches/Shader_HS18/programs/GLSL120/HW_VTFInstancing.vert

//---------------------------------------------------------------------------
//These materials/shaders are part of the NEW InstanceManager implementation
//Written by Matias N. Goldberg ("dark_sylinc")
//---------------------------------------------------------------------------
#version 120

//Vertex input
attribute vec4 vertex;
attribute vec3 normal;

#ifdef BONE_TWO_WEIGHTS
        attribute vec4 blendWeights;
#endif

attribute vec4 uv0;
attribute vec4 uv1;
attribute vec4 uv2;
        
#if BONE_MATRIX_LUT
        attribute vec4 uv3;
        attribute vec4 uv4;
        attribute vec4 uv5;
#endif

attribute vec3 tangent;

//Parameters
uniform mat4 viewProjMatrix;
uniform sampler2D matrixTexture;

#if (DEPTH_SHADOWCASTER || DEPTH_SHADOWRECEIVER)
uniform vec4 depthRange;
#endif

#if DEPTH_SHADOWRECEIVER
uniform mat4 texViewProjMatrix;
#endif

//Output
#if DEPTH_SHADOWCASTER
        varying vec2 depth;
#else
        varying vec2 _uv0;
        varying vec3 oNormal;
        varying vec3 oVPos;
        #if DEPTH_SHADOWRECEIVER
                varying vec4 oLightSpacePos;
        #endif
#endif

vec3 calculateBlendPosition(vec3 position, mat2x4 blendDQ)
{
        vec3 blendPosition = position + 2.0*cross(blendDQ[0].yzw, cross(blendDQ[0].yzw, position) + blendDQ[0].x*position);
        vec3 trans = 2.0*(blendDQ[0].x*blendDQ[1].yzw - blendDQ[1].x*blendDQ[0].yzw + cross(blendDQ[0].yzw, blendDQ[1].yzw));
        blendPosition += trans;

        return blendPosition;
}

vec3 calculateBlendNormal(vec3 normal, mat2x4 blendDQ)
{
        return normal + 2.0*cross(blendDQ[0].yzw, cross(blendDQ[0].yzw, normal) + blendDQ[0].x*normal);
}

//---------------------------------------------
//Main Vertex Shader
//---------------------------------------------
void main(void)
{
        vec4 worldPos;
        vec3 worldNorm;

#ifdef ST_DUAL_QUATERNION
        mat2x4 blendDQ; 
        blendDQ[0] = texture2D( matrixTexture, vec2(uv1.x, 0.0) + uv2.xy );
        blendDQ[1] = texture2D( matrixTexture, vec2(uv1.y, 0.0) + uv2.xy );
#ifdef BONE_TWO_WEIGHTS
        mat2x4 blendDQ2;
        blendDQ2[0] = texture2D( matrixTexture, vec2(uv1.z, 0.0) + uv2.xy );
        blendDQ2[1] = texture2D( matrixTexture, vec2(uv1.w, 0.0) + uv2.xy );

        //Accurate antipodality handling. For speed increase, remove the following line
        if (dot(blendDQ[0], blendDQ2[0]) < 0.0) blendDQ2 *= -1.0;
        
        //Blend the dual quaternions based on the weights
        blendDQ *= blendWeights.x;
        blendDQ += blendWeights.y*blendDQ2;
        //Normalize the resultant dual quaternion
        blendDQ /= length(blendDQ[0]);
#endif
        worldPos = vec4(calculateBlendPosition(vertex.xyz, blendDQ), 1.0);
        worldNorm = calculateBlendNormal(normal, blendDQ);
#else
        mat4 worldMatrix;
        worldMatrix[0] = texture2D( matrixTexture, uv1.xw + uv2.xy );
        worldMatrix[1] = texture2D( matrixTexture, uv1.yw + uv2.xy );
        worldMatrix[2] = texture2D( matrixTexture, uv1.zw + uv2.xy );
        worldMatrix[3] = vec4( 0, 0, 0, 1 );

        worldPos                = vertex * worldMatrix;
        worldNorm               = normal * mat3(worldMatrix);
#endif

#if BONE_MATRIX_LUT
        mat4 worldCompMatrix;
        worldCompMatrix[0] = uv3;
        worldCompMatrix[1] = uv4;
        worldCompMatrix[2] = uv5;
        worldCompMatrix[3] = vec4( 0, 0, 0, 1 );
        
        worldPos =  worldPos * worldCompMatrix;
        worldNorm = worldNorm * mat3(worldCompMatrix);
#endif

        //Transform the position
        gl_Position                     = viewProjMatrix * worldPos;
        
#if DEPTH_SHADOWCASTER
        depth.x                         = (gl_Position.z - depthRange.x) * depthRange.w;
        depth.y                         = depthRange.w;
#else
        _uv0            = uv0.xy;
        oNormal         = worldNorm;
        oVPos           = worldPos.xyz;

        #if DEPTH_SHADOWRECEIVER
                oLightSpacePos          = texViewProjMatrix * worldPos;
                oLightSpacePos.z        = (oLightSpacePos.z - depthRange.x) * depthRange.w;
        #endif
#endif
}