source: GTP/trunk/App/Demos/Illum/Ogre/Media/materials/programs/GameTools_DepthShadow.hlsl @ 1638

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

VS_OUT DepthVS(float4 position : POSITION,      
                                uniform float4x4 worldViewProj)
{
  
  VS_OUT OUT;
 
  OUT.hPosition = mul(worldViewProj, position);
  OUT.Position = mul(worldViewProj, position);
  
  return OUT;
}

//for directional light
float4 DepthPS(VS_OUT IN ):COLOR
{
//return 1;
        float4 pos = (IN.Position / IN.Position.w);
        //pos = (pos +1.0 ) / 2.0;
        return float4(pos.z, pos.z * pos.z, 1, 1);      
}

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

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

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

/*
float4 depthShadowPS(VS_OUT_SHADOW IN,
                                        uniform float4x4 lightViewProj,
                                        uniform sampler2D depthShadowMap : register(s0)
                                        ):COLOR
{       
        float bias = 0.001;
        float4 light = float4(1,1,1,1);
        float4 shadow = float4(0.85,0.85,0.85,1);
        //float4 shadow = float4(0,0,0,1);
        
        if(IN.lPosition.z > 0.0)
        {
                float4 pos = (IN.lPosition / IN.lPosition.w);
                
                if(length(pos.xy)>1)            
                        light = shadow;
                else
                {
                        pos.xy = (pos.xy + 1.0) / 2.0;
                        pos.y = 1.0 - pos.y;
                        float4 storedDepth = tex2D(depthShadowMap, pos.xy);
        
                        if(storedDepth.r + bias < pos.z)
                        {
                                float M1 = storedDepth.r;
                                float M2 = storedDepth.g;
                                float v2 = M2 - M1 * M1;
                                float pmax = v2 / (v2 + pow(M1 - pos.z, 2));
                                light = saturate(shadow + (1 - shadow) * pmax);
                        }
                }
                
        }
        else
                light = shadow; 
        
        return light;   
}
*/


float4 depthShadowPS(VS_OUT_SHADOW IN,
                                        uniform float4x4 lightViewProj,
                                        uniform sampler2D depthShadowMap : register(s0)
                                        ):COLOR
{       
        float bias = 0.0001;
        float4 light = float4(1,1,1,1);
        float4 shadow = float4(0.95,0.95,0.95,1);
        //float4 shadow = float4(0,0,0,1);
        
        if(IN.lPosition.z > 0.0)
        {
                float4 pos = (IN.lPosition / IN.lPosition.w);
                
                if(length(pos.xy)>1)            
                        light = shadow;
                else
                {
                        pos.xy = (pos.xy + 1.0) / 2.0;
                        pos.y = 1.0 - pos.y;
                        float4 storedDepth = tex2D(depthShadowMap, pos.xy);
        
                        if(storedDepth.r + bias < pos.z)
                        {
                                light = shadow;
                        }
                }
                
        }
        else
                light = shadow;
        
        
        return light;   
}