source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/depthOfField.cg @ 3235

#include "../shaderenv.h"

struct fragment
{
        float2 texCoords:  TEXCOORD0; 
};


float2 ComputeBlurFactors(float4 color, float sceneRange, float zFocus)
{
        float2 result;

        const float m = 1.0f;
        const float focalLen = 1.0f;

        const float scale = 5e4f;

        // Compute blur factor based on the CoC size scaled and normalized to 0..1 range
        //float blur = abs(dLens * focalLen * (zFocus - color.w)) / (1e-6f + abs(zFocus * (color.w - focalLen)));

        const float dist = abs(zFocus - color.w);
        const float blur = scale * m * focalLen * dist / (sceneRange * (1e-6f + abs(color.w + dist * step(0, zFocus - color.w))));
        
        //float blur = saturate(blur * scale / maxCoC);
        
        // Depth/blurriness value scaled to 0..1 range
        result = float2(color.w / sceneRange, blur);

        return result;
}


float4 Blur(float4 color, 
                        float2 texCoords,
                        float2 blurFactors,
                        sampler2D colorsTex,
                        float2 filterOffs[NUM_DOF_TABS]
                        )
{
        float4 avgCol = float4(.0f);
        float total_w = .0f;

        for (int i = 0; i < NUM_DOF_TABS; ++ i)
        {
                float2 sampleTexCoord = texCoords + filterOffs[i] * blurFactors.y;
                float4 sampleCol = tex2Dlod(colorsTex, float4(sampleTexCoord, 0, 0));
                
                // combine the weights
                float w = 1;
                
                avgCol += sampleCol * w;
                total_w += w;
        }

        avgCol /= max(total_w, 1e-6f);

        return avgCol;
}


float4 DepthOfField(fragment IN, 
                                        uniform sampler2D colorsTex,
                                        uniform float2 filterOffs[NUM_DOF_TABS],
                                        uniform float sceneRange,
                                        uniform float zFocus
                                         ): COLOR
{
        // center color
        const float4 color = tex2Dlod(colorsTex, float4(IN.texCoords, 0, 0));
        
        zFocus = min(zFocus, sceneRange * 0.5f);
        float2 blurFactors = ComputeBlurFactors(color, sceneRange, zFocus);

        //float4 outCol = float4(color.x, color.y, blurFactors.y, color.w);
        float4 outCol = Blur(color, IN.texCoords, blurFactors, colorsTex, filterOffs);
        
        return outCol;
}