source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/antialiasing.cg @ 3198

#include "../shaderenv.h"

struct fragment
{
        float2 texCoords:  TEXCOORD0; 
};

// the barrier for detecting a discontinuity (x = normal, y = depth)
//const uniform float4 barrier = float4(5e-5f, 5e-5f, 0, 0); 
const uniform float4 barrier = float4(0.6f, 9e-2f, 0, 0); 
// the weights for normal / depth discontinuity (x = normal, y = depth)
const uniform float4 weights = float4(0.5f, 0.5f, 1.0f, 1.0f); 
//uniform float4 weights = float4(1.0f, 1.0f, 1.0f, 1.0f);
// the maximal size of the filter kernel
const uniform float kernel = 0.5f; 



float4 main(fragment IN, 
                        uniform sampler2D colors,
                        uniform sampler2D normals,
                        uniform float2 offsets[8]): COLOR
{
        // center normal
        const float3 centerNormal = tex2Dlod(normals, float4(IN.texCoords, 0, 0)).xyz;
        // center color
        const float4 centerColor = tex2Dlod(colors, float4(IN.texCoords, 0, 0));
        // center depth
        const float4 centerDepth = float4(centerColor.w);
        
        const float2 lt = IN.texCoords + offsets[0];
        const float2 rb = IN.texCoords + offsets[1];
        const float2 rt = IN.texCoords + offsets[2];
        const float2 lb = IN.texCoords + offsets[3];

        // compute normal discontinuities
        float4 nd;

        nd.x = dot(centerNormal, tex2Dlod(normals, float4(lt, 0, 0)).xyz);
        nd.y = dot(centerNormal, tex2Dlod(normals, float4(rb, 0, 0)).xyz);
        nd.z = dot(centerNormal, tex2Dlod(normals, float4(rt, 0, 0)).xyz);
        nd.w = dot(centerNormal, tex2Dlod(normals, float4(lb, 0, 0)).xyz);

        nd -= float4(barrier.x);
        nd = step(float4(0.0f), nd);

        // weight the influence of normal discontinuities
        //const float ne = saturate(dot(nd, weights.x));
        const float ne = nd.x * nd.y * nd.z * nd.w * weights.x;


        ////////////
        // depth filter => compute gradient difference
        // (c - sample) + (c - opposite sample)

        float depthVals[8];

        for (int i = 0; i < 8; ++ i)
        {       
                depthVals[i] = (float)tex2Dlod(colors, float4(IN.texCoords + offsets[i], 0, 0)).w;
        }

        float4 dd; // the gradients

        dd[0] = depthVals[0] + depthVals[1];
        dd[1] = depthVals[2] + depthVals[3];
        dd[2] = depthVals[4] + depthVals[5];
        dd[3] = depthVals[6] + depthVals[7];

        //for (int i = 0; i < 4; ++ i)
        //      dd[i] = depthVals[i * 2] + depthVals[i * 2 + 1];
        
        //dd = abs(2.0f * (1.0f - abs(1.0f - centerDepth / dd))) - barrier.y;
        dd = abs(2.0f * centerDepth - dd) - barrier.y;
        dd = step(dd, float4(0.0f));

        //const float de = saturate(dot(dd, weights.y));
        const float de = weights.y * dd.x * dd.y * dd.z * dd.w;


        ///////////////////////////

        // weight: 0 = no antialiasing, 1 = full antialiasing
        const float w = (1.0f - de * ne) * kernel.x;
        // smoothed color: the offset is big where discontinuities are
        // (a - c) * w + c = a * w + c * (1 - w)
        const float2 width = IN.texCoords * (1.0f - w);

        float4 s0 = tex2Dlod(colors, float4(width + lt * w, 0, 0));
        float4 s1 = tex2Dlod(colors, float4(width + rb * w, 0, 0));
        float4 s2 = tex2Dlod(colors, float4(width + rt * w, 0, 0));
        float4 s3 = tex2Dlod(colors, float4(width + lb * w, 0, 0));


        //float4 col = (s0 + s1 + s2 + s3 + centerColor) * 0.2f;
        float4 col = (s0 + s1 + s2 + s3) * 0.25f;
        //float4 col = float4(ne.x, ne.x, ne.x, 0);
        //float4 col = float4(de.x, de.x, de.x, 0);
        //float4 col = float4(w, w, w, 0);
        
        // push through the current depth
        col.w = centerDepth.x;

        return col;
}