source: data/data_extern/programs/Cg/ShaderInstancing.cg

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

//---------------------------------------------
//Vertex Shader Input
//---------------------------------------------
struct VS_INPUT
{
        float4 Position :       POSITION;
        float3 Normal   :       NORMAL;
        float3 Tangent  :       TANGENT;
        float2 uv0      :       TEXCOORD0;

        float4 BlendIdx :       BLENDINDICES;
        float4 BlendWgt :       BLENDWEIGHT;
};

#include "InstancingVertexInterpolators.cg"
#ifdef ST_DUAL_QUATERNION
#include "DualQuaternionSkinning_Shadow.cg"
#endif

//---------------------------------------------
//Main Vertex Shader
//---------------------------------------------
VS_OUTPUT main_vs( in VS_INPUT input,
                                   uniform float4x4 viewProjMatrix,
#ifdef ST_DUAL_QUATERNION
                                   uniform float2x4 worldDualQuaternion2x4Array[120]
#else
                                   uniform float3x4 worldMatrix3x4Array[80]
#endif
#if defined( DEPTH_SHADOWCASTER ) || defined( DEPTH_SHADOWRECEIVER )
                                ,  uniform float4 depthRange
#endif
#ifdef DEPTH_SHADOWRECEIVER
                                ,  uniform float4x4 texViewProjMatrix
#endif
                                   )
{
        VS_OUTPUT output;

        float4 worldPos  = 0;
        float3 worldNorm = 0;

        int idx = int(input.BlendIdx[0]);
#ifdef ST_DUAL_QUATERNION
        //Only dealing with one weight so normalization of the dual quaternion and weighting are unnecessary
        float2x4 blendDQ = worldDualQuaternion2x4Array[idx];
#ifdef BONE_TWO_WEIGHTS
        float2x4 blendDQ2 = worldDualQuaternion2x4Array[int(input.BlendIdx[1])];
        
        //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 *= input.BlendWgt.x;
        blendDQ += input.BlendWgt.y*blendDQ2;
        //Normalize the resultant dual quaternion
        blendDQ /= length(blendDQ[0]);
#endif
        worldPos = float4(calculateBlendPosition(input.Position, blendDQ), 1.0);
        worldNorm = calculateBlendNormal(input.Normal, blendDQ);
#else
        worldPos  = float4( mul( worldMatrix3x4Array[idx], input.Position ).xyz, 1.0f );
        worldNorm = mul( (float3x3)(worldMatrix3x4Array[idx]), input.Normal );
#endif

        /*int i;
        for( i=0; i<4; i++ )
        {
                int idx = int(input.BlendIdx[0]);
                worldPos += float4( mul( worldMatrix3x4Array[idx], input.Position ).xyz, 1.0f ) * input.BlendWgt[i];
                worldNorm += mul( (float3x3)(worldMatrix3x4Array[idx]), input.Normal ) * input.BlendWgt[i];
        }*/

        //Transform the position
        output.Position         = mul( viewProjMatrix, worldPos );
        
#ifdef DEPTH_SHADOWCASTER
        output.ps.unused        = float3( 0 );
        output.ps.depth         = (output.Position.z - depthRange.x + SHADOW_BIAS) * depthRange.w;
#else
        output.ps.uv0           = input.uv0;
        
        //Pass Normal and position for Blinn Phong lighting
        output.ps.Normal        = normalize(worldNorm);
        output.ps.vPos          = worldPos.xyz;

        #ifdef DEPTH_SHADOWRECEIVER
                // Calculate the position of vertex in light space to do shadows
                output.ps.lightSpacePos = mul( texViewProjMatrix, worldPos );
                // make linear
                output.ps.lightSpacePos.z = (output.ps.lightSpacePos.z - depthRange.x) * depthRange.w;
        #endif
#endif

        return output;
}