166 lines
4.2 KiB
GLSL
166 lines
4.2 KiB
GLSL
/**
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* @file WLCloudsV.glsl
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*
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* Copyright (c) 2005-$CurrentYear$, Linden Research, Inc.
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* $License$
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*/
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//////////////////////////////////////////////////////////////////////////
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// The vertex shader for creating the atmospheric sky
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///////////////////////////////////////////////////////////////////////////////
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// Output parameters
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varying vec4 vary_CloudColorSun;
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varying vec4 vary_CloudColorAmbient;
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varying float vary_CloudDensity;
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// Inputs
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uniform vec3 camPosLocal;
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uniform vec4 lightnorm;
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uniform vec4 sunlight_color;
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uniform vec4 ambient;
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uniform vec4 blue_horizon;
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uniform vec4 blue_density;
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uniform vec4 haze_horizon;
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uniform vec4 haze_density;
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uniform vec4 cloud_shadow;
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uniform vec4 density_multiplier;
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uniform vec4 max_y;
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uniform vec4 glow;
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uniform vec4 cloud_color;
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uniform vec4 cloud_scale;
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void main()
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{
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// World / view / projection
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gl_Position = ftransform();
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gl_TexCoord[0] = gl_MultiTexCoord0;
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// Get relative position
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vec3 P = gl_Vertex.xyz - camPosLocal.xyz + vec3(0,50,0);
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// Set altitude
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if (P.y > 0.)
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{
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P *= (max_y.x / P.y);
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}
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else
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{
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P *= (-32000. / P.y);
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}
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// Can normalize then
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vec3 Pn = normalize(P);
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float Plen = length(P);
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// Initialize temp variables
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vec4 temp1 = vec4(0.);
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vec4 temp2 = vec4(0.);
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vec4 blue_weight;
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vec4 haze_weight;
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vec4 sunlight = sunlight_color;
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vec4 light_atten;
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// Sunlight attenuation effect (hue and brightness) due to atmosphere
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// this is used later for sunlight modulation at various altitudes
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light_atten = (blue_density * 1.0 + haze_density.x * 0.25) * (density_multiplier.x * max_y.x);
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// Calculate relative weights
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temp1 = blue_density + haze_density.x;
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blue_weight = blue_density / temp1;
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haze_weight = haze_density.x / temp1;
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// Compute sunlight from P & lightnorm (for long rays like sky)
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temp2.y = max(0., max(0., Pn.y) * 1.0 + lightnorm.y );
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temp2.y = 1. / temp2.y;
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sunlight *= exp( - light_atten * temp2.y);
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// Distance
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temp2.z = Plen * density_multiplier.x;
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// Transparency (-> temp1)
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// ATI Bugfix -- can't store temp1*temp2.z in a variable because the ati
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// compiler gets confused.
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temp1 = exp(-temp1 * temp2.z);
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// Compute haze glow
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temp2.x = dot(Pn, lightnorm.xyz);
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temp2.x = 1. - temp2.x;
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// temp2.x is 0 at the sun and increases away from sun
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temp2.x = max(temp2.x, .001);
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// Set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
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temp2.x *= glow.x;
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// Higher glow.x gives dimmer glow (because next step is 1 / "angle")
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temp2.x = pow(temp2.x, glow.z);
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// glow.z should be negative, so we're doing a sort of (1 / "angle") function
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// Add "minimum anti-solar illumination"
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temp2.x += .25;
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// Increase ambient when there are more clouds
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vec4 tmpAmbient = ambient;
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tmpAmbient += (1. - tmpAmbient) * cloud_shadow.x * 0.5;
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// Dim sunlight by cloud shadow percentage
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sunlight *= (1. - cloud_shadow.x);
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// Haze color below cloud
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vec4 additiveColorBelowCloud = ( blue_horizon * blue_weight * (sunlight + tmpAmbient)
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+ (haze_horizon.r * haze_weight) * (sunlight * temp2.x + tmpAmbient)
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);
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// CLOUDS
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sunlight = sunlight_color;
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temp2.y = max(0., lightnorm.y * 2.);
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temp2.y = 1. / temp2.y;
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sunlight *= exp( - light_atten * temp2.y);
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// Cloud color out
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vary_CloudColorSun = (sunlight * temp2.x) * cloud_color;
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vary_CloudColorAmbient = tmpAmbient * cloud_color;
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// Attenuate cloud color by atmosphere
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temp1 = sqrt(temp1); //less atmos opacity (more transparency) below clouds
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vary_CloudColorSun *= temp1;
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vary_CloudColorAmbient *= temp1;
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vec4 oHazeColorBelowCloud = additiveColorBelowCloud * (1. - temp1);
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// Make a nice cloud density based on the cloud_shadow value that was passed in.
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vary_CloudDensity = 2. * (cloud_shadow.x - 0.25);
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// Texture coords
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gl_TexCoord[0] = gl_MultiTexCoord0;
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gl_TexCoord[0].xy -= 0.5;
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gl_TexCoord[0].xy /= cloud_scale.x;
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gl_TexCoord[0].xy += 0.5;
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gl_TexCoord[1] = gl_TexCoord[0];
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gl_TexCoord[1].x += lightnorm.x * 0.0125;
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gl_TexCoord[1].y += lightnorm.z * 0.0125;
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gl_TexCoord[2] = gl_TexCoord[0] * 16.;
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gl_TexCoord[3] = gl_TexCoord[1] * 16.;
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// Combine these to minimize register use
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vary_CloudColorAmbient += oHazeColorBelowCloud;
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// needs this to compile on mac
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//vary_AtmosAttenuation = vec3(0.0,0.0,0.0);
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// END CLOUDS
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}
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