30 lines
1.1 KiB
C#
30 lines
1.1 KiB
C#
#define PI 3.14
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extern float xresolution;
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//从1D距离map采样
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float samp(vec2 coord,float r,Image u_texture){
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return step(r,Texel(u_texture,coord).r);
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}
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vec4 effect(vec4 color,Image texture,vec2 texture_coords,vec2 screen_coords){
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//直角转极坐标，用于采样1D材质的y总是0
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vec2 norm=texture_coords.st*2.-1.;
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float r=length(norm);
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vec2 tc=vec2((atan(norm.y,norm.x)+PI)/(2.*PI),0.);
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//根据离光源距离放大模糊系数，模拟影子淡出
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float blur=(1./xresolution)*smoothstep(0.,1.,r);
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//简易高斯模糊
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float sum=
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samp(vec2(tc.x-4.*blur,tc.y),r,texture)*.5
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+samp(vec2(tc.x-3.*blur,tc.y),r,texture)*.9
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+samp(vec2(tc.x-2.*blur,tc.y),r,texture)*.12
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+samp(vec2(tc.x-1.*blur,tc.y),r,texture)*.15
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+samp(tc,r,texture)*.16//The center tex coord,which gives us hard shadows.
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+samp(vec2(tc.x+1.*blur,tc.y),r,texture)*.15
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+samp(vec2(tc.x+2.*blur,tc.y),r,texture)*.12
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+samp(vec2(tc.x+3.*blur,tc.y),r,texture)*.9
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+samp(vec2(tc.x+4.*blur,tc.y),r,texture)*.5;
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//sum值为亮度(0~1)
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//乘上距离得到逐渐变淡的光线
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return vec4(vec3(1.),sum*smoothstep(1.,.1,r));
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} |