172 lines
6.7 KiB
GLSL
172 lines
6.7 KiB
GLSL
/**
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* @file class2\windlight\atmosphericsFuncs.glsl
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*
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* $LicenseInfo:firstyear=2022&license=viewerlgpl$
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* Second Life Viewer Source Code
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* Copyright (C) 2022, 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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uniform vec3 lightnorm;
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uniform vec3 sunlight_color;
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uniform vec3 sunlight_linear;
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uniform vec3 moonlight_color;
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uniform vec3 moonlight_linear;
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uniform int sun_up_factor;
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uniform vec3 ambient_color;
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uniform vec3 ambient_linear;
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uniform vec3 blue_horizon;
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uniform vec3 blue_horizon_linear;
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uniform vec3 blue_density;
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uniform vec3 blue_density_linear;
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uniform float haze_horizon;
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uniform float haze_density;
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uniform float haze_density_linear;
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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 vec3 glow;
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uniform float scene_light_strength;
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uniform mat3 ssao_effect_mat;
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uniform int no_atmo;
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uniform float sun_moon_glow_factor;
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float getAmbientClamp() { return 1.0f; }
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vec3 srgb_to_linear(vec3 col);
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// return colors in sRGB space
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void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive,
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out vec3 atten, bool use_ao)
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{
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vec3 rel_pos = inPositionEye;
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//(TERRAIN) limit altitude
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if (abs(rel_pos.y) > max_y) rel_pos *= (max_y / rel_pos.y);
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vec3 rel_pos_norm = normalize(rel_pos);
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float rel_pos_len = length(rel_pos);
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vec3 sunlight = (sun_up_factor == 1) ? sunlight_color : moonlight_color;
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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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vec3 light_atten = (blue_density + vec3(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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vec3 combined_haze = blue_density + vec3(haze_density);
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vec3 blue_weight = blue_density / combined_haze;
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vec3 haze_weight = vec3(haze_density) / combined_haze;
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//(TERRAIN) compute sunlight from lightnorm y component. Factor is roughly cosecant(sun elevation) (for short rays like terrain)
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float above_horizon_factor = 1.0 / max(1e-6, lightnorm.y);
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sunlight *= exp(-light_atten * above_horizon_factor); // for sun [horizon..overhead] this maps to an exp curve [0..1]
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// main atmospheric scattering line integral
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float density_dist = rel_pos_len * density_multiplier;
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// Transparency (-> combined_haze)
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// ATI Bugfix -- can't store combined_haze*density_dist*distance_multiplier in a variable because the ati
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// compiler gets confused.
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combined_haze = exp(-combined_haze * density_dist * distance_multiplier);
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// final atmosphere attenuation factor
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atten = combined_haze.rgb;
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// compute haze glow
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float haze_glow = dot(rel_pos_norm, lightnorm.xyz);
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// dampen sun additive contrib when not facing it...
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// SL-13539: This "if" clause causes an "additive" white artifact at roughly 77 degreees.
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// if (length(light_dir) > 0.01)
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haze_glow *= max(0.0f, dot(light_dir, rel_pos_norm));
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haze_glow = 1. - haze_glow;
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// haze_glow is 0 at the sun and increases away from sun
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haze_glow = max(haze_glow, .001); // set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
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haze_glow *= glow.x;
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// higher glow.x gives dimmer glow (because next step is 1 / "angle")
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haze_glow = pow(haze_glow, 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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haze_glow += .25;
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haze_glow *= sun_moon_glow_factor;
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vec3 amb_color = ambient_color;
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// increase ambient when there are more clouds
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vec3 tmpAmbient = amb_color + (vec3(1.) - amb_color) * cloud_shadow * 0.5;
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/* decrease value and saturation (that in HSV, not HSL) for occluded areas
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* // for HSV color/geometry used here, see http://gimp-savvy.com/BOOK/index.html?node52.html
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* // The following line of code performs the equivalent of:
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* float ambAlpha = tmpAmbient.a;
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* float ambValue = dot(vec3(tmpAmbient), vec3(0.577)); // projection onto <1/rt(3), 1/rt(3), 1/rt(3)>, the neutral white-black axis
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* vec3 ambHueSat = vec3(tmpAmbient) - vec3(ambValue);
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* tmpAmbient = vec4(RenderSSAOEffect.valueFactor * vec3(ambValue) + RenderSSAOEffect.saturationFactor *(1.0 - ambFactor) * ambHueSat,
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* ambAlpha);
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*/
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if (use_ao)
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{
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tmpAmbient = mix(ssao_effect_mat * tmpAmbient.rgb, tmpAmbient.rgb, ambFactor);
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}
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// Similar/Shared Algorithms:
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// indra\llinventory\llsettingssky.cpp -- LLSettingsSky::calculateLightSettings()
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// indra\newview\app_settings\shaders\class1\windlight\atmosphericsFuncs.glsl -- calcAtmosphericVars()
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// haze color
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vec3 cs = sunlight.rgb * (1. - cloud_shadow);
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additive = (blue_horizon.rgb * blue_weight.rgb) * (cs + tmpAmbient.rgb) + (haze_horizon * haze_weight.rgb) * (cs * haze_glow + tmpAmbient.rgb);
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// brightness of surface both sunlight and ambient
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sunlit = sunlight.rgb;
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amblit = tmpAmbient.rgb;
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additive *= vec3(1.0 - combined_haze);
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}
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vec3 srgb_to_linear(vec3 col);
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// provide a touch of lighting in the opposite direction of the sun light
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// so areas in shadow don't lose all detail
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float ambientLighting(vec3 norm, vec3 light_dir)
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{
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float ambient = min(abs(dot(norm.xyz, light_dir.xyz)), 1.0);
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ambient *= 0.56;
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ambient *= ambient;
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ambient = (1.0 - ambient);
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return ambient;
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}
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// return colors in linear space
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void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 additive,
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out vec3 atten)
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{
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calcAtmosphericVars(inPositionEye, light_dir, 1.0, sunlit, amblit, additive, atten, false);
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sunlit = srgb_to_linear(sunlit);
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additive = srgb_to_linear(additive);
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amblit = ambient_linear;
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amblit *= ambientLighting(norm, light_dir);
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}
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