21 lines
731 B
GLSL
21 lines
731 B
GLSL
#define PI 3.14
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extern float yresolution;
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vec4 effect(vec4 color,Image tex,vec2 tex_coords,vec2 screen_coords){
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// Iterate through the occluder map's y-axis.
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for(float y=0.;y<yresolution;y++){
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// Cartesian to polar
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// y/yresolution=distance to light source(0~1)
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vec2 norm=vec2(tex_coords.s,y/yresolution)*2.-1.;
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float theta=PI*1.5+norm.x*PI;
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float r=(1.+norm.y)*0.5;
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//sample from solid
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if(
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Texel(tex,(
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vec2(-r*sin(theta),-r*cos(theta))*0.5+0.5// Coord of solid sampling
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)).a>0.1
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)return vec4(vec3(y/yresolution),1.);// Collision check, alpha>0.1 means transparent
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}
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return vec4(1.);// Return max distance 1
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}
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