158 lines
4.9 KiB
GLSL
158 lines
4.9 KiB
GLSL
/**
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* @file atmosphericsV.glsl
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*
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* $LicenseInfo:firstyear=2005&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2005, Linden Research, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation;
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* version 2.1 of the License only.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
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* $/LicenseInfo$
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*/
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// VARYING param funcs
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void setSunlitColor(vec3 v);
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void setAmblitColor(vec3 v);
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void setAdditiveColor(vec3 v);
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void setAtmosAttenuation(vec3 v);
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void setPositionEye(vec3 v);
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vec3 getAdditiveColor();
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//VARYING vec4 vary_CloudUVs;
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//VARYING float vary_CloudDensity;
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// Inputs
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uniform vec4 morphFactor;
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uniform vec3 camPosLocal;
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//uniform vec4 camPosWorld;
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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 float haze_horizon;
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uniform float haze_density;
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uniform float cloud_shadow;
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uniform float density_multiplier;
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uniform float distance_multiplier;
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uniform float max_y;
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uniform vec4 glow;
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void calcAtmospherics(vec3 inPositionEye) {
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vec3 P = inPositionEye;
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setPositionEye(P);
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//(TERRAIN) limit altitude
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if (P.y > max_y) P *= (max_y / P.y);
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if (P.y < -max_y) P *= (-max_y / P.y);
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vec3 tmpLightnorm = lightnorm.xyz;
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vec3 Pn = normalize(P);
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float Plen = length(P);
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vec4 temp1 = vec4(0);
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vec3 temp2 = vec3(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 + vec4(haze_density * 0.25)) * (density_multiplier * max_y);
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//I had thought blue_density and haze_density should have equal weighting,
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//but attenuation due to haze_density tends to seem too strong
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temp1 = blue_density + vec4(haze_density);
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blue_weight = blue_density / temp1;
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haze_weight = vec4(haze_density) / temp1;
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//(TERRAIN) compute sunlight from lightnorm only (for short rays like terrain)
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temp2.y = max(0.0, tmpLightnorm.y);
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temp2.y = 1. / temp2.y;
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sunlight *= exp( - light_atten * temp2.y);
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// main atmospheric scattering line integral
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temp2.z = Plen * density_multiplier;
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// Transparency (-> temp1)
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// ATI Bugfix -- can't store temp1*temp2.z*distance_multiplier in a variable because the ati
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// compiler gets confused.
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temp1 = exp(-temp1 * temp2.z * distance_multiplier);
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//final atmosphere attenuation factor
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setAtmosAttenuation(temp1.rgb);
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//vary_AtmosAttenuation = distance_multiplier / 10000.;
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//vary_AtmosAttenuation = density_multiplier * 100.;
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//vary_AtmosAttenuation = vec4(Plen / 100000., 0., 0., 1.);
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//compute haze glow
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//(can use temp2.x as temp because we haven't used it yet)
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temp2.x = dot(Pn, tmpLightnorm.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, .03); //was glow.y
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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 + (vec4(1.) - ambient) * cloud_shadow * 0.5;
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//haze color
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setAdditiveColor(
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vec3(blue_horizon * blue_weight * (sunlight*(1.-cloud_shadow) + tmpAmbient)
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+ (haze_horizon * haze_weight) * (sunlight*(1.-cloud_shadow) * temp2.x
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+ tmpAmbient)));
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//brightness of surface both sunlight and ambient
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setSunlitColor(vec3(sunlight * .5));
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setAmblitColor(vec3(tmpAmbient * .25));
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setAdditiveColor(getAdditiveColor() * vec3(1.0 - temp1));
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// vary_SunlitColor = vec3(0);
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// vary_AmblitColor = vec3(0);
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// vary_AdditiveColor = vec4(Pn, 1.0);
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/*
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const float cloudShadowScale = 100.;
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// Get cloud uvs for shadowing
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vec3 cloudPos = inPositionEye + camPosWorld - cloudShadowScale / 2.;
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vary_CloudUVs.xy = cloudPos.xz / cloudShadowScale;
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// We can take uv1 and multiply it by (TerrainSpan / CloudSpan)
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// cloudUVs *= (((worldMaxZ - worldMinZ) * 20) /40000.);
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vary_CloudUVs *= (10000./40000.);
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// Offset by sun vector * (CloudAltitude / CloudSpan)
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vary_CloudUVs.x += tmpLightnorm.x / tmpLightnorm.y * (3000./40000.);
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vary_CloudUVs.y += tmpLightnorm.z / tmpLightnorm.y * (3000./40000.);
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*/
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}
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