41 lines
867 B
GLSL
41 lines
867 B
GLSL
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#version 120
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// Atmospheric scattering shader for flightgear
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// Written by Lauri Peltonen (Zan)
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// Implementation of O'Neil's algorithm
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varying vec3 rayleigh;
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varying vec3 mie;
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varying vec3 eye;
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float miePhase(in float cosTheta, in float g)
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{
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float g2 = g*g;
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float a = 1.5 * (1.0 - g2);
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float b = (2.0 + g2);
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float c = 1.0 + cosTheta*cosTheta;
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float d = pow(1.0 + g2 - 2.0 * g * cosTheta, 0.6667);
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return (a*c) / (b*d);
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}
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float rayleighPhase(in float cosTheta)
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{
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//return 1.5 * (1.0 + cosTheta*cosTheta);
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return 1.5 * (2.0 + 0.5*cosTheta*cosTheta);
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}
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void main()
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{
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float cosTheta = dot(normalize(eye), gl_LightSource[0].position.xyz);
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vec3 color = rayleigh * rayleighPhase(cosTheta);
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color += mie * miePhase(cosTheta, -0.8);
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gl_FragColor = vec4(color, 1.0);
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gl_FragDepth = 0.1;
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}
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