lens_flare.sha

//Cg
// Second part of lens flare postprocess filter from this article http://www.john-chapman.net/content.php?id=18
// Panda3d interpretation by 09th (rupanda3d@gmail.com)
void vshader(
    float4 vtx_position : POSITION,
    float2 vtx_texcoord0 : TEXCOORD0,
    out float4 l_position : POSITION,
    out float2 l_texcoord0 : TEXCOORD0,
    out float2 l_texcoord1 : TEXCOORD1,
    uniform float4 texpad_tex1,
    uniform float4x4 mat_modelproj)
{
    l_position=mul(mat_modelproj, vtx_position);
    l_texcoord0 = vtx_position.xz * texpad_tex1.xy + texpad_tex1.xy;
    //l_texcoord0 = vtx_position.xz + float2(0.4, 0.3);// * texpad_tex.xy + texpad_tex.xy;
    l_texcoord1 = 1.0 - (vtx_position.xz * texpad_tex1.xy - texpad_tex1.xy);
    
}
 
void fshader(float2 l_texcoord0 : TEXCOORD0,
              float2 l_texcoord1 : TEXCOORD1,
             out float4 o_color : COLOR,
             uniform float4 texpad_tex1,
             uniform sampler2D k_tex1 : TEXUNIT0,
             uniform sampler2D k_tex2 : TEXUNIT1,
             uniform sampler2D k_tex3 : TEXUNIT2)
{
    int NSAMPLES = 5;
    float FLARE_HALO_WIDTH = 0.2;
    float FLARE_DISPERSAL = 0.3;
    float3 CHROMA_DISTORT = float3(0.004, -0.004, 0.0);
    
    float4 c = tex2D(k_tex1, l_texcoord0);

    float2 sample_vector = (texpad_tex1.xy - l_texcoord0) * FLARE_DISPERSAL;
    float2 halo_vector = normalize(sample_vector) * FLARE_HALO_WIDTH;
    float3 tmp = float3(0.0);
    float3 result = 0.0;
    result.x = tex2D(k_tex3, l_texcoord0 + halo_vector + halo_vector * CHROMA_DISTORT.x).x;
    result.y = tex2D(k_tex3, l_texcoord0 + halo_vector + halo_vector * CHROMA_DISTORT.y).y;
    result.z = tex2D(k_tex3, l_texcoord0 + halo_vector + halo_vector * CHROMA_DISTORT.z).z;
    for (int i = 0; i < NSAMPLES; ++i) {
        float2 offset = sample_vector * float(i);
        tmp.x = tex2D(k_tex3, l_texcoord0 + offset + offset  * CHROMA_DISTORT.x).x;
        tmp.y = tex2D(k_tex3, l_texcoord0 + offset + offset  * CHROMA_DISTORT.y).y;
        tmp.z = tex2D(k_tex3, l_texcoord0 + offset + offset  * CHROMA_DISTORT.z).z;
        result += tmp;
    }
        
    result /= float(NSAMPLES);
 
    o_color = (float4(result.x + c.x, result.y + c.y, result.z + c.z, 1.0));// +
              //tex2D(k_tex3, l_texcoord0));
}