256 lines
9.5 KiB
GLSL
256 lines
9.5 KiB
GLSL
// -*-C++-*-
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#version 120
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varying float fogFactor;
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varying vec3 hazeColor;
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uniform float range; // From /sim/rendering/clouds3d-vis-range
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uniform float detail_range; // From /sim/rendering/clouds3d_detail-range
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uniform float scattering;
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uniform float terminator;
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uniform float altitude;
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uniform float cloud_self_shading;
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uniform float visibility;
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uniform float moonlight;
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uniform float air_pollution;
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uniform float flash;
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uniform float lightning_pos_x;
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uniform float lightning_pos_y;
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uniform float lightning_range;
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attribute vec3 usrAttr1;
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attribute vec3 usrAttr2;
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float alpha_factor = usrAttr1.r;
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float shade_factor = usrAttr1.g;
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float cloud_height = usrAttr1.b;
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float bottom_factor = usrAttr2.r;
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float middle_factor = usrAttr2.g;
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float top_factor = usrAttr2.b;
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const float EarthRadius = 5800000.0;
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// light_func is a generalized logistic function fit to the light intensity as a function
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// of scaled terminator position obtained from Flightgear core
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float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
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{
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x = x-0.5;
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// use the asymptotics to shorten computations
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if (x > 30.0) {return e;}
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if (x < -15.0) {return 0.03;}
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return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
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}
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float mie_func (in float x, in float Mie)
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{
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return x + 2.0 * x * Mie * (1.0 -0.8*x) * (1.0 -0.8*x);
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}
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void main(void)
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{
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//shade_factor = shade_factor * cloud_self_shading;
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//top_factor = top_factor * cloud_self_shading;
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//shade_factor = min(shade_factor, top_factor);
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//middle_factor = min(middle_factor, top_factor);
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//bottom_factor = min(bottom_factor, top_factor);
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float intensity;
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float mix_factor;
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vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
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vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight * scattering;
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gl_TexCoord[0] = gl_MultiTexCoord0;
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vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
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vec4 l = gl_ModelViewMatrixInverse * vec4(0.0,0.0,1.0,1.0);
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vec3 u = normalize(ep.xyz - l.xyz);
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// Find a rotation matrix that rotates 1,0,0 into u. u, r and w are
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// the columns of that matrix.
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vec3 absu = abs(u);
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vec3 r = normalize(vec3(-u.y, u.x, 0.0));
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vec3 w = cross(u, r);
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// Do the matrix multiplication by [ u r w pos]. Assume no
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// scaling in the homogeneous component of pos.
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gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
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gl_Position.xyz = gl_Vertex.x * u;
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gl_Position.xyz += gl_Vertex.y * r;
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gl_Position.xyz += gl_Vertex.z * w;
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// Apply Z scaling to allow sprites to be squashed in the z-axis
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gl_Position.z = gl_Position.z * gl_Color.w;
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// Now shift the sprite to the correct position in the cloud.
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gl_Position.xyz += gl_Color.xyz;
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// Determine a lighting normal based on the vertex position from the
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// center of the cloud, so that sprite on the opposite side of the cloud to the sun are darker.
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float n = dot(normalize(-gl_LightSource[0].position.xyz),
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normalize(vec3(gl_ModelViewMatrix * vec4(- gl_Position.x, - gl_Position.y, - gl_Position.z, 0.0))));
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// Determine the position - used for fog and shading calculations
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float fogCoord = length(vec3(gl_ModelViewMatrix * vec4(gl_Color.x, gl_Color.y, gl_Color.z, 1.0)));
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float center_dist = length(vec3(gl_ModelViewMatrix * vec4(0.0,0.0,0.0,1.0)));
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if ((fogCoord > detail_range) && (fogCoord > center_dist) && (shade_factor < 0.7)) {
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// More than detail_range away, so discard all sprites on opposite side of
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// cloud center by shifting them beyond the view fustrum
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gl_Position = vec4(0.0,0.0,10.0,1.0);
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gl_FrontColor.a = 0.0;
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} else {
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// Determine the shading of the vertex. We shade it based on it's position
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// in the cloud relative to the sun, and it's vertical position in the cloud.
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float shade = mix(shade_factor, top_factor, smoothstep(-0.3, 0.3, n));
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//if (n < 0) {
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// shade = mix(top_factor, shade_factor, abs(n));
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//}
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if (gl_Position.z < 0.5 * cloud_height) {
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shade = min(shade, mix(bottom_factor, middle_factor, gl_Position.z * 2.0 / cloud_height));
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} else {
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shade = min(shade, mix(middle_factor, top_factor, gl_Position.z * 2.0 / cloud_height - 1.0));
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}
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//float h = gl_Position.z / cloud_height;
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//if (h < 0.5) {
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// shade = min(shade, mix(bottom_factor, middle_factor, smoothstep(0.0, 0.5, h)));
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//} else {
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// shade = min(shade, mix(middle_factor, top_factor, smoothstep(2.0 * (h - 0.5)));
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// }
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// Final position of the sprite
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vec3 relVector = gl_Position.xyz - ep.xyz;
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gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
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// Light at the final position
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// first obtain normal to sun position
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vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
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vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
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// yprime is the distance of the vertex into sun direction, corrected for altitude
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// the altitude correction is clamped to reasonable values, sometimes altitude isn't parsed correctly, leading
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// to overbright or overdark clouds
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// float vertex_alt = clamp(altitude * 0.30480 + relVector.z,1000.0,10000.0);
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float vertex_alt = clamp(altitude + relVector.z, 300.0, 10000.0);
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float yprime = -dot(relVector, lightHorizon);
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float yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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// two times terminator width governs how quickly light fades into shadow
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float terminator_width = 200000.0;
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float earthShade = 1.0- 0.9* smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt);
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float earthShadeFactor = 1.0 - smoothstep(0.4, 0.5, earthShade);
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// compute the light at the position
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vec4 light_diffuse;
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float lightArg = (terminator-yprime_alt)/100000.0;
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light_diffuse.b = light_func(lightArg -1.2 * air_pollution, 1.330e-05, 0.264, 2.227, 1.08e-05, 1.0);
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light_diffuse.g = light_func(lightArg -0.6 * air_pollution, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
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light_diffuse.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
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light_diffuse.a = 1.0;
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//light_diffuse *= cloud_self_shading;
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intensity = (1.0 - (0.8 * (1.0 - earthShade))) * length(light_diffuse.rgb);
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light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, (1.0 - smoothstep(0.5,0.9, min(scattering, cloud_self_shading) ))));
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// correct ambient light intensity and hue before sunrise
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if (earthShade < 0.6)
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{
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light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.6,earthShade ) ));
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}
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gl_FrontColor.rgb = intensity * shade * normalize(mix(light_diffuse.rgb, shadedFogColor, smoothstep(0.1,0.4, (1.0 - shade) ))) ;
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// lightning
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vec2 lightningRelVector = relVector.xy - vec2(lightning_pos_x, lightning_pos_y);
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float rCoord = length(lightningRelVector);
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float rn = 0.5 + 0.5 * fract(gl_Color.x);
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gl_FrontColor.rgb += flash * vec3 (0.43, 0.57, 1.0) * (1.0 - smoothstep(lightning_range, 5.0 * lightning_range, rCoord)) * rn;
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// fading of cloudlets
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if ((fogCoord > (0.9 * detail_range)) && (fogCoord > center_dist) && (shade_factor < 0.7)) {
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// cloudlet is almost at the detail range, so fade it out.
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gl_FrontColor.a = 1.0 - smoothstep(0.9 * detail_range, detail_range, fogCoord);
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} else {
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// As we get within 100m of the sprite, it is faded out. Equally at large distances it also fades out.
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gl_FrontColor.a = min(smoothstep(10.0, 100.0, fogCoord), 1.0 - smoothstep(0.9 * range, range, fogCoord));
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}
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gl_FrontColor.a = gl_FrontColor.a * (1.0 - smoothstep(visibility, 3.0* visibility, fogCoord));
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fogFactor = exp(-fogCoord/visibility);
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// haze of ground haze shader is slightly bluish
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hazeColor = light_diffuse.rgb;
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hazeColor.r = hazeColor.r * 0.83;
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hazeColor.g = hazeColor.g * 0.9;
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hazeColor = hazeColor * scattering;
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// Mie correction
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float Mie = 0.0;
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float MieFactor = 0.0;
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if (bottom_factor > 0.4)
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{
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MieFactor = dot(normalize(lightFull), normalize(relVector));
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Mie = 1.5 * smoothstep(0.9,1.0, MieFactor) * smoothstep(0.6, 0.8, bottom_factor) * (1.0-earthShadeFactor) ;
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//if (MieFactor < 0.0) {Mie = - Mie;}
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}
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//else {Mie = 0.0;}
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if (Mie > 0.0)
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{
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hazeColor.r = mie_func(hazeColor.r, Mie);
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hazeColor.g = mie_func(hazeColor.g, 0.8* Mie);
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hazeColor.b = mie_func(hazeColor.b, 0.5* Mie);
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gl_FrontColor.r = mie_func(gl_FrontColor.r, Mie);
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gl_FrontColor.g = mie_func(gl_FrontColor.g, 0.8* Mie);
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gl_FrontColor.b = mie_func(gl_FrontColor.b, 0.5*Mie);
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}
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else if (MieFactor < 0.0)
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{
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float thickness_reduction = smoothstep(0.4, 0.8, bottom_factor) ;
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float light_reduction = dot (lightFull, lightHorizon);
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light_reduction *= light_reduction;
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float factor_b = 0.8 + 0.2 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
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float factor_r = 0.6 + 0.4 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
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float factor_g = 0.65 + 0.35 * (1.0 - smoothstep(0.0, 0.7, -MieFactor) * thickness_reduction * light_reduction) ;
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hazeColor.r *= factor_r;
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hazeColor.g *= factor_g;
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hazeColor.b *= factor_b;
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gl_FrontColor.r *= factor_r;
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gl_FrontColor.g *= factor_g;
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gl_FrontColor.b *= factor_b;
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}
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gl_FrontColor.rgb = gl_FrontColor.rgb + moonLightColor * earthShadeFactor;
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hazeColor.rgb = hazeColor.rgb + moonLightColor * earthShadeFactor;
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gl_FrontColor.a = gl_FrontColor.a * alpha_factor;
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gl_BackColor = gl_FrontColor;
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}
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}
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