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/**
* @file class1\windlight\atmosphericsFuncs.glsl
*
* $LicenseInfo:firstyear=2005&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2019, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 moonlight_color;
uniform int sun_up_factor;
uniform vec4 ambient_color;
uniform vec4 blue_horizon;
uniform vec4 blue_density;
uniform float haze_horizon;
uniform float haze_density;
uniform float cloud_shadow;
uniform float density_multiplier;
uniform float distance_multiplier;
uniform float max_y;
uniform vec4 glow;
uniform float scene_light_strength;
uniform mat3 ssao_effect_mat;
uniform int no_atmo;
uniform float sun_moon_glow_factor;
float getAmbientClamp()
{
return 1.0f;
}
void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive, out vec3 atten, bool use_ao) {
vec3 P = inPositionEye;
//(TERRAIN) limit altitude
if (P.y > max_y) P *= (max_y / P.y);
if (P.y < -max_y) P *= (-max_y / P.y);
vec3 tmpLightnorm = lightnorm.xyz;
vec3 Pn = normalize(P);
float Plen = length(P);
vec4 temp1 = vec4(0);
vec3 temp2 = vec3(0);
vec4 blue_weight;
vec4 haze_weight;
vec4 sunlight = (sun_up_factor == 1) ? sunlight_color : moonlight_color;
vec4 light_atten;
float dens_mul = density_multiplier;
float dist_mul = distance_multiplier;
//sunlight attenuation effect (hue and brightness) due to atmosphere
//this is used later for sunlight modulation at various altitudes
light_atten = (blue_density + vec4(haze_density * 0.25)) * (dens_mul * max_y);
//I had thought blue_density and haze_density should have equal weighting,
//but attenuation due to haze_density tends to seem too strong
temp1 = blue_density + vec4(haze_density);
blue_weight = blue_density / temp1;
haze_weight = vec4(haze_density) / temp1;
//(TERRAIN) compute sunlight from lightnorm only (for short rays like terrain)
temp2.y = max(0.0, tmpLightnorm.y);
if (abs(temp2.y) > 0.000001f)
{
temp2.y = 1. / abs(temp2.y);
}
temp2.y = max(0.0000001f, temp2.y);
sunlight *= exp(-light_atten * temp2.y);
// main atmospheric scattering line integral
temp2.z = Plen * dens_mul;
// Transparency (-> temp1)
// ATI Bugfix -- can't store temp1*temp2.z*dist_mul in a variable because the ati
// compiler gets confused.
temp1 = exp(-temp1 * temp2.z * dist_mul);
//final atmosphere attenuation factor
atten = temp1.rgb;
//compute haze glow
//(can use temp2.x as temp because we haven't used it yet)
temp2.x = dot(Pn, tmpLightnorm.xyz);
// dampen sun additive contrib when not facing it...
if (length(light_dir) > 0.01)
{
temp2.x *= max(0.0f, dot(light_dir, Pn));
}
temp2.x = 1. - temp2.x;
//temp2.x is 0 at the sun and increases away from sun
temp2.x = max(temp2.x, .001); //was glow.y
//set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
temp2.x *= glow.x;
//higher glow.x gives dimmer glow (because next step is 1 / "angle")
temp2.x = pow(temp2.x, glow.z);
//glow.z should be negative, so we're doing a sort of (1 / "angle") function
//add "minimum anti-solar illumination"
temp2.x += .25;
temp2.x *= sun_moon_glow_factor;
vec4 amb_color = ambient_color;
//increase ambient when there are more clouds
vec4 tmpAmbient = amb_color + (vec4(1.) - amb_color) * cloud_shadow * 0.5;
/* decrease value and saturation (that in HSV, not HSL) for occluded areas
* // for HSV color/geometry used here, see http://gimp-savvy.com/BOOK/index.html?node52.html
* // The following line of code performs the equivalent of:
* float ambAlpha = tmpAmbient.a;
* float ambValue = dot(vec3(tmpAmbient), vec3(0.577)); // projection onto <1/rt(3), 1/rt(3), 1/rt(3)>, the neutral white-black axis
* vec3 ambHueSat = vec3(tmpAmbient) - vec3(ambValue);
* tmpAmbient = vec4(RenderSSAOEffect.valueFactor * vec3(ambValue) + RenderSSAOEffect.saturationFactor *(1.0 - ambFactor) * ambHueSat, ambAlpha);
*/
if (use_ao)
{
tmpAmbient = vec4(mix(ssao_effect_mat * tmpAmbient.rgb, tmpAmbient.rgb, ambFactor), tmpAmbient.a);
}
//haze color
additive =
vec3(blue_horizon * blue_weight * (sunlight*(1.-cloud_shadow) + tmpAmbient)
+ (haze_horizon * haze_weight) * (sunlight*(1.-cloud_shadow) * temp2.x
+ tmpAmbient));
//brightness of surface both sunlight and ambient
sunlit = sunlight.rgb * 0.5;
amblit = tmpAmbient.rgb * .25;
additive *= vec3(1.0 - temp1);
}
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