276 lines
8.3 KiB
GLSL
276 lines
8.3 KiB
GLSL
// -*-C++-*-
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#version 120
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// Shader that uses OpenGL state values to do per-pixel lighting
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//
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// The only light used is gl_LightSource[0], which is assumed to be
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// directional.
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//
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// Diffuse colors come from the gl_Color, ambient from the material. This is
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// equivalent to osg::Material::DIFFUSE.
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// Haze part added by Thorsten Renk, Oct. 2011
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#define MODE_OFF 0
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#define MODE_DIFFUSE 1
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#define MODE_AMBIENT_AND_DIFFUSE 2
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// The constant term of the lighting equation that doesn't depend on
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// the surface normal is passed in gl_{Front,Back}Color. The alpha
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// component is set to 1 for front, 0 for back in order to work around
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// bugs with gl_FrontFacing in the fragment shader.
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varying vec3 relPos;
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varying float yprime_alt;
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varying float autumn_flag;
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uniform int colorMode;
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uniform int wind_effects;
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uniform int forest_effects;
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uniform int num_deciduous_trees;
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uniform float hazeLayerAltitude;
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uniform float terminator;
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uniform float terrain_alt;
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uniform float avisibility;
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uniform float visibility;
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uniform float overcast;
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uniform float ground_scattering;
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uniform float snow_level;
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uniform float season;
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uniform float forest_effect_size;
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uniform float forest_effect_shape;
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uniform float WindN;
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uniform float WindE;
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uniform float osg_SimulationTime;
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uniform int cloud_shadow_flag;
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uniform bool use_forest_effect;
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float earthShade;
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float mie_angle;
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float shadow_func (in float x, in float y, in float noise, in float dist);
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float VoronoiNoise2D(in vec2 coord, in float wavelength, in float xrand, in float yrand);
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// This is the value used in the skydome scattering shader - use the same here for consistency?
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const float EarthRadius = 5800000.0;
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const float terminator_width = 200000.0;
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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 < -15.0) {return 0.0;}
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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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void main()
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{
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vec4 light_ambient;
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vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
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float yprime;
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float lightArg;
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float intensity;
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float vertex_alt;
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float scattering;
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// this code is copied from tree.vert
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float numVarieties = gl_Normal.z;
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float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties;
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// determine whether the tree changes color in autumn
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if (texFract < float(num_deciduous_trees)/float(numVarieties)) {autumn_flag = 0.5 + fract(gl_Color.x);}
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else {autumn_flag = 0.0;}
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texFract += floor(gl_MultiTexCoord0.x) / numVarieties;
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// Determine the rotation for the tree. The Fog Coordinate provides rotation information
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// to rotate one of the quands by 90 degrees. We then apply an additional position seed
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// so that trees aren't all oriented N/S
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float sr = sin(gl_FogCoord + gl_Color.x);
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float cr = cos(gl_FogCoord + gl_Color.x);
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gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0);
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// Determine the y texture coordinate based on whether it's summer, winter, snowy.
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gl_TexCoord[0].y = gl_TexCoord[0].y + 0.25 * step(snow_level, gl_Color.z) + 0.5 * season;
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// scaling
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vec3 position = gl_Vertex.xyz * gl_Normal.xxy;
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// Rotation of the generic quad to specific one for the tree.
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position.xy = vec2(dot(position.xy, vec2(cr, sr)), dot(position.xy, vec2(-sr, cr)));
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// Shear by wind. Note that this only applies to the top vertices
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if (wind_effects > 0)
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{
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position.x = position.x + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindN;
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position.y = position.y + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindE;
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}
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// Scale by random domains
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float voronoi;
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if ((forest_effects > 0)&& use_forest_effect)
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{
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voronoi = 0.5 + 1.0 * VoronoiNoise2D(gl_Color.xy, forest_effect_size, forest_effect_shape, forest_effect_shape);
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position.xyz = position.xyz * voronoi;
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}
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// Move to correct location (stored in gl_Color)
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position = position + gl_Color.xyz;
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gl_Position = gl_ModelViewProjectionMatrix * vec4(position,1.0);
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vec3 ecPosition = vec3(gl_ModelViewMatrix * vec4(position, 1.0));
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//normal = normalize(-ecPosition);
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//float n = dot(normalize(gl_LightSource[0].position.xyz), normalize(-ecPosition));
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//vec4 diffuse_color = gl_FrontMaterial.diffuse * max(0.1, n);
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//diffuse_color.a = 1.0;
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vec4 ambient_color = gl_FrontMaterial.ambient;
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// here start computations for the haze layer
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// we need several geometrical quantities
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// first current altitude of eye position in model space
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vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
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// and relative position to vector
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relPos = position - ep.xyz;
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// unfortunately, we need the distance in the vertex shader, although the more accurate version
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// is later computed in the fragment shader again
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float dist = length(relPos);
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// altitude of the vertex in question, somehow zero leads to artefacts, so ensure it is at least 100m
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vertex_alt = max(position.z,100.0);
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scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, vertex_alt);
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// branch dependent on daytime
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if (terminator < 1000000.0) // the full, sunrise and sunset computation
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{
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// establish coordinates relative 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
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yprime = -dot(relPos, lightHorizon);
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// this gets an altitude correction, higher terrain gets to see the sun earlier
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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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// now the light-dimming factor
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earthShade = 0.6 * (1.0 - smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt)) + 0.4;
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// parametrized version of the Flightgear ground lighting function
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lightArg = (terminator-yprime_alt)/100000.0;
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// directional scattering for low sun
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if (lightArg < 10.0)
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{mie_angle = (0.5 * dot(normalize(relPos), normalize(lightFull)) ) + 0.5;}
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else
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{mie_angle = 1.0;}
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light_ambient.r = light_func(lightArg, 0.236, 0.253, 1.073, 0.572, 0.33);
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light_ambient.g = light_ambient.r * 0.4/0.33;
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light_ambient.b = light_ambient.r * 0.5/0.33;
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light_ambient.a = 1.0;
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// correct ambient light intensity and hue before sunrise
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if (earthShade < 0.5)
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{
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//light_ambient = light_ambient * (0.4 + 0.6 * smoothstep(0.2, 0.5, earthShade));
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intensity = length(light_ambient.rgb);
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light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,earthShade) ));
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}
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// the haze gets the light at the altitude of the haze top if the vertex in view is below
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// but the light at the vertex if the vertex is above
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vertex_alt = max(vertex_alt,hazeLayerAltitude);
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if (vertex_alt > hazeLayerAltitude)
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{
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if (dist > 0.8 * avisibility)
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{
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vertex_alt = mix(vertex_alt, hazeLayerAltitude, smoothstep(0.8*avisibility, avisibility, dist));
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yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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}
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}
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else
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{
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vertex_alt = hazeLayerAltitude;
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yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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}
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}
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else // the faster, full-day version without lightfields
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{
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earthShade = 1.0;
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mie_angle = 1.0;
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if (terminator > 3000000.0)
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{light_ambient = vec4 (0.33, 0.4, 0.5, 1.0); }
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else
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{
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lightArg = (terminator/100000.0 - 10.0)/20.0;
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light_ambient.r = 0.316 + lightArg * 0.016;
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light_ambient.g = light_ambient.r * 0.4/0.33;
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light_ambient.b = light_ambient.r * 0.5/0.33;
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light_ambient.a = 1.0;
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}
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yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
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}
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light_ambient.rgb = light_ambient.rgb * (1.0 + smoothstep(1000000.0, 3000000.0,terminator));
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// tree shader lighting
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if (cloud_shadow_flag == 1)
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{light_ambient.rgb = light_ambient.rgb * (0.5 + 0.5 * shadow_func(relPos.x, relPos.y, 1.0, dist));}
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//vec4 ambientColor = gl_FrontLightModelProduct.sceneColor +
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//gl_FrontColor = ambientColor;
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gl_FrontColor = light_ambient * gl_FrontMaterial.ambient;
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gl_FrontColor.a = mie_angle; gl_BackColor.a = mie_angle;
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}
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