4564b30eac
Previously haze calculations were performed in the main body of the ws30 shaders (inherited from the ALS terrain shaders). This change creates a common applyHaze function to consistently apply haze. This is not ws30 specific, and could be used to replace the haze calculations of all ALS shaders for improved consistency.
245 lines
7.4 KiB
GLSL
245 lines
7.4 KiB
GLSL
// WS30 VERTEX SHADER
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// -*-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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// Colors are not assigned in this shader, as they will come from
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// the landclass lookup in the fragment shader.
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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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// From VPBTechnique.cxx
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uniform mat4 fg_zUpTransform;
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uniform vec3 fg_modelOffset;
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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 vec4 light_diffuse_comp;
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varying vec3 normal;
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varying vec3 relPos;
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varying vec2 ground_tex_coord;
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varying vec4 ecPosition;
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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 moonlight;
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void setupShadows(vec4 eyeSpacePos);
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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 earthShade;
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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_diffuse;
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vec4 light_ambient;
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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;
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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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// this code is copied from default.vert
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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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// Temporary value:
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ground_tex_coord = gl_TexCoord[0].st;
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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 = (fg_zUpTransform * vec4(gl_Vertex - 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(relPos.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_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.a = 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.xyz);
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light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.4, 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.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, 1.0 -smoothstep(0.4, 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 = vec4 (1.0, 1.0, 1.0, 0.0);
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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_diffuse.a = 1.0;
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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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light_diffuse = light_diffuse * scattering;
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yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
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}
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// default lighting based on texture and material using the light we have just computed
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light_diffuse_comp = light_diffuse;
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//Testing phase code: ambient colours are not sent to fragement shader yet.
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// They are all default except for water/ocean etc. currently
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// Emission is all set to the default of vec4(0.0, 0.0, 0.0, 1.0)
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//To do: Fix this once ambient colour becomes available in the fragment shaders.
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//const vec4 ambient_color = vec4(0.2, 0.2, 0.2, 1.0);
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vec4 constant_term = gl_LightModel.ambient + light_ambient;
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// Another hack for supporting two-sided lighting without using
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// gl_FrontFacing in the fragment shader.
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gl_FrontColor.rgb = constant_term.rgb;
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gl_BackColor.rgb = constant_term.rgb;
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gl_FrontColor.a = mie_angle;
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gl_BackColor.a = mie_angle;
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setupShadows(ecPosition);
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}
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