278 lines
8 KiB
GLSL
278 lines
8 KiB
GLSL
// -*-C++-*-
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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 vec2 rawPos;
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varying vec3 VNormal;
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varying vec3 VTangent;
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varying vec4 ecPosition;
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varying vec4 constantColor;
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varying vec3 light_diffuse;
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varying float yprime_alt;
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varying float mie_angle;
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uniform int colorMode;
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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 eye_alt;
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uniform float moonlight;
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attribute vec3 tangent;//, binormal;
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float earthShade;
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float steepness;
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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(0.65, 0.67, 0.78);
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vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight;
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//float yprime_alt;
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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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rawPos = gl_Vertex.xy;
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steepness = dot(normalize(gl_Normal), vec3 (0.0, 0.0, 1.0));
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VNormal = normalize(gl_NormalMatrix * gl_Normal);
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ecPosition = gl_ModelViewMatrix * gl_Vertex;
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// Normal = normalize(gl_Normal);
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VTangent = gl_NormalMatrix * tangent;
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// VBinormal = gl_NormalMatrix * binormal;
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// this code is copied from default.vert
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//vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
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gl_Position = ftransform();
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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//normal = gl_NormalMatrix * gl_Normal;
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vec4 ambient_color, diffuse_color;
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if (colorMode == MODE_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_FrontMaterial.ambient;
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} else if (colorMode == MODE_AMBIENT_AND_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_Color;
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} else {
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diffuse_color = gl_FrontMaterial.diffuse;
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ambient_color = gl_FrontMaterial.ambient;
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}
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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 = gl_Vertex.xyz - 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(gl_Vertex.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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// early culling of vertices which can't be seen due to ground haze despite being in aloft visibility range
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float delta_z = hazeLayerAltitude - eye_alt;
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//if (((dist * (relPos.z - delta_z)/relPos.z > visibility ) && (relPos.z < 0.0) && (delta_z < 0.0) && (dist > 30000.0)))
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if (0==1)
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{
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gl_Position = vec4(0.0, 0.0, -1000.0, 1.0); // move outside of view frustrum, gets culled before reaching fragment shader
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earthShade = 1.0;
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mie_angle = 1.0;
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yprime_alt = 0.0;
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}
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else
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{
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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_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0);
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light_diffuse.g = light_func(lightArg, 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 = light_diffuse * scattering;
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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 * (0.7 + 0.3 * 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.xyz, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,earthShade) ));
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light_ambient.rgb = light_ambient.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade));
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intensity = length(light_diffuse.xyz);
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light_diffuse.xyz = intensity * normalize(mix(light_diffuse.xyz, shadedFogColor, 1.0 -smoothstep(0.1, 0.7,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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//vertex_alt = max(gl_Vertex.z,100.0);
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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_diffuse = vec3 (1.0, 1.0, 1.0);
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light_ambient = vec4 (0.33, 0.4, 0.5, 0.0); }
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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_diffuse.b = 0.78 + lightArg * 0.21;
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light_diffuse.g = 0.907 + lightArg * 0.091;
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light_diffuse.r = 0.904 + lightArg * 0.092;
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light_ambient.b = 0.41 + lightArg * 0.08;
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light_ambient.g = 0.333 + lightArg * 0.06;
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light_ambient.r = 0.316 + lightArg * 0.016;
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}
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light_diffuse = light_diffuse * scattering;
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yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
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}
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// a sky/earth irradiation map model - the sky creates much more diffuse radiation than the ground, so
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// steep faces end up shaded more
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light_ambient = light_ambient * ((1.0+steepness)/2.0 * 1.2 + (1.0-steepness)/2.0 * 0.2);
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// default lighting based on texture and material using the light we have just computed
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gl_FrontColor = gl_Color;
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constantColor = gl_FrontMaterial.emission
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+ gl_Color * (gl_LightModel.ambient + light_ambient);
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}
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}
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