source: GTP/trunk/App/Demos/Illum/Ogre/Media/materials/programs/GameTools_DepthShadow.hlsl @ 1102

///////depth map
struct VS_OUT
{
        float4 hPosition        : POSITION;
        float4 Position : TEXCOORD0;
};

VS_OUT hDepthVS(float4 position : POSITION,     
                uniform float4x4 worldView,
                uniform float4x4 worldViewProj)
{
  
  VS_OUT OUT;
  OUT.hPosition = mul(worldViewProj, position);
  OUT.Position = mul(worldView, position);
  OUT.Position.z *= -1.0;
  return OUT;
}



float4 DepthPS(VS_OUT IN ):COLOR
{
        float dist = length(IN.Position.xyz);
        return float4(dist, dist, dist, 1);
        //return 1;     
}

///////////////Shadow

struct VS_OUT_SHADOW
{
        float4 hPosition        : POSITION;
        float4 Position         : TEXCOORD0;
        float4 cPosition        : TEXCOORD1;
};

VS_OUT_SHADOW depthShadowVS(float4 position : POSITION, 
                uniform float4x4 world,
                uniform float4x4 worldView,
                uniform float4x4 worldViewProj)
{
  VS_OUT_SHADOW OUT;
  OUT.hPosition = mul(worldViewProj, position);
  OUT.Position = mul(world, position);
  OUT.cPosition = mul(worldView, position);
  return OUT;
}


float4 depthShadowPS(VS_OUT_SHADOW IN,
                                        uniform float4x4 lightView,
                                        uniform float4x4 lightViewProj,
                                        uniform float4x4 lightView2,
                                        uniform float4x4 lightViewProj2,
                                        uniform sampler2D depthShadowMap : register(s0),
                                        uniform sampler2D depthShadowMap2 : register(s1)):COLOR
{                                       
        float bias = 0.06;
        float4 shadowColor = float4(0.6, 0.6, 0.6, 1.0);

        float4 light1 = float4(1,1,1,1);
        
        float4 lightCamPos1 = mul(lightView, IN.Position);
        float d1 = length(lightCamPos1.xyz);    
        float4 lightScreenPos1 = mul(lightViewProj, IN.Position);
        lightScreenPos1 = lightScreenPos1 / lightScreenPos1.w ; 
        lightScreenPos1 = ( lightScreenPos1 + 1.0 ) / 2.0;
        lightScreenPos1.y = 1.0 - lightScreenPos1.y;
        float4 storedDepth1 = tex2D(depthShadowMap, lightScreenPos1.xy);
                if(storedDepth1.r + bias < d1)
                        light1 = shadowColor;   
        
        
        return light1;  
}