invert_threshold_r_blur.sha

//Cg
// First 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,
    uniform float4 texpad_tex1,
    uniform float4x4 mat_modelproj)
{
    l_position=mul(mat_modelproj, vtx_position);
    // invert texture coord
    l_texcoord0 = - (vtx_position.xz * texpad_tex1.xy*2);
}
 
void fshader(float2 l_texcoord0 : TEXCOORD0,
             out float4 o_color : COLOR,
             uniform float4 texpad_tex1,
             uniform sampler2D k_tex1 : TEXUNIT0,
             uniform float3 k_threshold)
{

    int NSAMPLES = 3;
    float BlurStart = 0.5;
    float BlurWidth = -0.1;
    float BRIGHTNESS = 1.0;
   
    // threshold + radial blur
    float4 c = 0;
    float3 tmp = 0;
    for(int i=0; i <NSAMPLES; i++) {
        float scale = BlurStart + BlurWidth*(i/(float) (NSAMPLES-1));
        tmp = tex2D(k_tex1, l_texcoord0 * scale + texpad_tex1.xy ).xyz;
        tmp = saturate((((tmp - k_threshold)/(float3(1.0) - k_threshold))) * BRIGHTNESS);
        c += float4(tmp, 1.0);
    }
    c /= NSAMPLES;
   
    o_color = c;

}