16 lines
654 B
C#
16 lines
654 B
C#
#define PI 3.14
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extern float yresolution;
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vec4 effect(vec4 color,Image texture,vec2 texture_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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//直角转极坐标
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vec2 norm=vec2(texture_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)*.5;
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//y/yresolution为到光源的距离(0~1)
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//遮光物采样
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vec4 data=Texel(texture,(vec2(-r*sin(theta),-r*cos(theta))*.5+.5));//vec2()..是遮光物采样的coord
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if(data.a>.1)return vec4(vec3(y/yresolution),1.);//碰撞检测，像素透明度>.1即透光
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}
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return vec4(1,1,1,1);//返回最远距离1
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} |