45 lines
1.3 KiB
GLSL
45 lines
1.3 KiB
GLSL
!!cvarf crep_decay
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!!cvarf crep_density
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!!cvarf crep_weight
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!!samps 1
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//this is a post-processing shader, drawn in 2d
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//there will be a render target containing sky surfaces drawn with crepuscular_sky, and everything else drawn with crepuscular_opaque (to mask out the sky)
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//this shader then just smudges the sky out a bit as though its coming from the sun or whatever through the clouds.
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//yoinked from http://fabiensanglard.net/lightScattering/index.php
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varying vec2 tc;
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#ifdef VERTEX_SHADER
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attribute vec2 v_texcoord;
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void main ()
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{
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tc = v_texcoord;
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gl_Position = vec4(v_position, 1.0);
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}
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#endif
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#ifdef FRAGMENT_SHADER
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const float crep_decay = 0.94;
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const float crep_density = 0.5;
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const float crep_weight = 0.2;
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uniform vec3 l_lightcolour;
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uniform vec3 l_lightscreen;
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const int NUM_SAMPLES = 100;
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void main()
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{
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vec2 deltaTextCoord = vec2(tc.st - l_lightscreen.xy);
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vec2 textCoo = tc.st;
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deltaTextCoord *= 1.0 / float(NUM_SAMPLES) * crep_density;
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float illuminationDecay = 1.0;
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gl_FragColor = vec4(0.0,0.0,0.0,0.0);
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for(int i=0; i < NUM_SAMPLES ; i++)
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{
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textCoo -= deltaTextCoord;
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vec4 sample = texture2D(s_t0, textCoo);
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sample *= illuminationDecay * crep_weight;
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gl_FragColor += sample;
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illuminationDecay *= crep_decay;
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}
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gl_FragColor *= vec4(l_lightcolour, 1.0);
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}
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#endif
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