source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/lenseFlare.cg @ 3215

#include "../shaderenv.h"

struct fragment
{
        float2 texCoords:  TEXCOORD0; 
};


inline float2 ComputeTexCoords(float2 tex, float2 v, float dist, float scale, float distScale)
{
        const float2 center = float2(.5f, .5f);
        const float2 newPos = -v * dist * distScale;
        //const float2 newPos = v * dist * distScale;

        //return (tex - center - newPos) / scale + newPos + center;
        return (tex - center) / scale + center + newPos / scale;
        //return tex / scale - center;// + center + newPos;
}


inline float4 ComputeColor(sampler2D tex, float2 texCoords, float2 v, float dist, float scale, float distScale)
{
        const float2 newTexCoords = ComputeTexCoords(texCoords, v, dist, scale, distScale);
        return tex2Dlod(tex, float4(newTexCoords, 0, 0));
}


float4 LenseFlare(fragment IN, 
                                  uniform sampler2D colorsTex,
                                  uniform sampler2D flareTex1,
                                  uniform sampler2D flareTex2,
                                  uniform sampler2D flareTex3,
                                  uniform sampler2D flareTex4,
                                  uniform sampler2D flareTex5,
                                  uniform float2 vectorToLight, // vector to current light position
                                  uniform float distanceToLight, // distance to current light position
                                  uniform float sunVisiblePixels
                                  ): COLOR
{
        // center color
        const float4 color = tex2Dlod(colorsTex, float4(IN.texCoords, 0, 0));
        
        const float scale = 0.3f;

        float4 flare[8];

        flare[0] = ComputeColor(flareTex1, IN.texCoords, vectorToLight, distanceToLight, 1.0f * scale, 1.0f);
        flare[1] = ComputeColor(flareTex2, IN.texCoords, vectorToLight, distanceToLight, 0.7f * scale, 1.0f / 3.0f);
        flare[2] = ComputeColor(flareTex3, IN.texCoords, vectorToLight, distanceToLight, 0.25f * scale, 0.7f);
        flare[3] = ComputeColor(flareTex4, IN.texCoords, vectorToLight, distanceToLight, .7f * scale, -1.0f / 2.0f);
        flare[4] = ComputeColor(flareTex3, IN.texCoords, vectorToLight, distanceToLight, .4f * scale, -1.0f / 6.0f);

        flare[5] = ComputeColor(flareTex5, IN.texCoords, vectorToLight, distanceToLight, .1f * scale, 0.5f);
        flare[6] = ComputeColor(flareTex5, IN.texCoords, vectorToLight, distanceToLight, .2f * scale, -0.25f);

        flare[7] = ComputeColor(flareTex2, IN.texCoords, vectorToLight, distanceToLight, 1.0f * scale, -1.0f);

        float4 result = color;

        //result.xyz = float3(0);
        sunVisiblePixels = clamp(sunVisiblePixels, .0f, 100.0f) * 0.01f;

        for (int i = 0; i < 8; ++ i)
                result.xyz += flare[i].xyz * sunVisiblePixels;

        return result;
}