source: downloads/Samples/Media/materials/programs/Example_Fresnel.cg @ 3

// Vertex program for fresnel reflections / refractions
void main_vp(
                float4 pos                      : POSITION,
                float4 normal           : NORMAL,
                float2 tex                      : TEXCOORD0,
                
                out float4 oPos         : POSITION,
                out float3 noiseCoord : TEXCOORD0,
                out float4 projectionCoord : TEXCOORD1,
                out float3 oEyeDir : TEXCOORD2, 
                out float3 oNormal : TEXCOORD3, 

                uniform float4x4 worldViewProjMatrix,
                uniform float3 eyePosition, // object space
                uniform float timeVal,
                uniform float scale,  // the amount to scale the noise texture by
                uniform float scroll, // the amount by which to scroll the noise
                uniform float noise  // the noise perturb as a factor of the  time
                )
{
        oPos = mul(worldViewProjMatrix, pos);
        // Projective texture coordinates, adjust for mapping
        float4x4 scalemat = float4x4(0.5,   0,   0, 0.5, 
                                       0,-0.5,   0, 0.5,
                                                                   0,   0, 0.5, 0.5,
                                                                   0,   0,   0,   1);
        projectionCoord = mul(scalemat, oPos);
        // Noise map coords
        noiseCoord.xy = (tex + (timeVal * scroll)) * scale;
        noiseCoord.z = noise * timeVal;

        oEyeDir = normalize(pos.xyz - eyePosition); 
        oNormal = normal.rgb; 
        
}

// Fragment program for distorting a texture using a 3D noise texture
void main_fp(
                float3 noiseCoord                       : TEXCOORD0,
                float4 projectionCoord          : TEXCOORD1,
                float3 eyeDir                           : TEXCOORD2,
                float3 normal                           : TEXCOORD3,
                
                out float4 col          : COLOR,
                
                uniform float4 tintColour,
                uniform float noiseScale, 
                uniform float fresnelBias,
                uniform float fresnelScale,
                uniform float fresnelPower,
                uniform sampler2D noiseMap : register(s0),
                uniform sampler2D reflectMap : register(s1),
                uniform sampler2D refractMap : register(s2)
                )
{
        // Do the tex projection manually so we can distort _after_
        float2 final = projectionCoord.xy / projectionCoord.w;

        // Noise
        float3 noiseNormal = (tex2D(noiseMap, (noiseCoord.xy / 5)).rgb - 0.5).rbg * noiseScale;
        final += noiseNormal.xz;

        // Fresnel
        //normal = normalize(normal + noiseNormal.xz);
        float fresnel = fresnelBias + fresnelScale * pow(1 + dot(eyeDir, normal), fresnelPower);

        // Reflection / refraction
        float4 reflectionColour = tex2D(reflectMap, final);
        float4 refractionColour = tex2D(refractMap, final) + tintColour;

        // Final colour
        col = lerp(refractionColour, reflectionColour, fresnel);


}


// Old version to match ATI PS 1.3 implementation
void main_vp_old(
                float4 pos                      : POSITION,
                float4 normal           : NORMAL,
                float2 tex                      : TEXCOORD0,
                
                out float4 oPos         : POSITION,
                out float fresnel   : COLOR,
                out float3 noiseCoord : TEXCOORD0,
                out float4 projectionCoord : TEXCOORD1,

                uniform float4x4 worldViewProjMatrix,
                uniform float3 eyePosition, // object space
                uniform float fresnelBias,
                uniform float fresnelScale,
                uniform float fresnelPower,
                uniform float timeVal,
                uniform float scale,  // the amount to scale the noise texture by
                uniform float scroll, // the amount by which to scroll the noise
                uniform float noise  // the noise perturb as a factor of the  time
                )
{
        oPos = mul(worldViewProjMatrix, pos);
        // Projective texture coordinates, adjust for mapping
        float4x4 scalemat = float4x4(0.5,   0,   0, 0.5, 
                                       0,-0.5,   0, 0.5,
                                                                   0,   0, 0.5, 0.5,
                                                                   0,   0,   0,   1);
        projectionCoord = mul(scalemat, oPos);
        // Noise map coords
        noiseCoord.xy = (tex + (timeVal * scroll)) * scale;
        noiseCoord.z = noise * timeVal;

        // calc fresnel factor (reflection coefficient)
        float3 eyeDir = normalize(pos.xyz - eyePosition);
        fresnel = fresnelBias + fresnelScale * pow(1 + dot(eyeDir, normal), fresnelPower);
        
}