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/**
* @file class2\wl\skyV.glsl
*
* $LicenseInfo:firstyear=2005&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2005, 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 mat4 modelview_projection_matrix;
ATTRIBUTE vec3 position;
// SKY ////////////////////////////////////////////////////////////////////////
// The vertex shader for creating the atmospheric sky
///////////////////////////////////////////////////////////////////////////////
// Output parameters
VARYING vec3 vary_HazeColor;
// Inputs
uniform vec3 camPosLocal;
uniform vec3 lightnorm;
uniform vec3 sunlight_color;
uniform vec3 moonlight_color;
uniform int sun_up_factor;
uniform vec3 ambient_color;
uniform vec3 blue_horizon;
uniform vec3 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 vec3 glow;
uniform float sun_moon_glow_factor;
void main()
{
// World / view / projection
vec4 pos = modelview_projection_matrix * vec4(position.xyz, 1.0);
gl_Position = pos;
// Get relative position
vec3 rel_pos = position.xyz - camPosLocal.xyz + vec3(0, 50, 0);
// Adj position vector to clamp altitude
if (rel_pos.y > 0.)
{
rel_pos *= (max_y / rel_pos.y);
}
if (rel_pos.y < 0.)
{
rel_pos *= (-32000. / rel_pos.y);
}
// Can normalize then
vec3 rel_pos_norm = normalize(rel_pos);
float rel_pos_len = length(rel_pos);
// Initialize temp variables
vec3 sunlight = (sun_up_factor == 1) ? sunlight_color : moonlight_color;
vec3 light_atten;
// Sunlight attenuation effect (hue and brightness) due to atmosphere
// this is used later for sunlight modulation at various altitudes
light_atten = (blue_density + vec3(haze_density * 0.25)) * (density_multiplier * max_y);
// Calculate relative weights
vec3 combined_haze = abs(blue_density) + vec3(abs(haze_density));
vec3 blue_weight = blue_density / combined_haze;
vec3 haze_weight = haze_density / combined_haze;
// Compute sunlight from rel_pos & lightnorm (for long rays like sky)
float off_axis = 1.0 / max(1e-6, max(0., rel_pos_norm.y) + lightnorm.y);
sunlight *= exp(-light_atten * off_axis);
// Distance
float density_dist = rel_pos_len * density_multiplier;
// Transparency (-> combined_haze)
// ATI Bugfix -- can't store combined_haze*density_dist in a variable because the ati
// compiler gets confused.
combined_haze = exp(-combined_haze * density_dist);
// Compute haze glow
float haze_glow = 1.0 - dot(rel_pos_norm, lightnorm.xyz);
// haze_glow is 0 at the sun and increases away from sun
haze_glow = max(haze_glow, .001);
// Set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
haze_glow *= glow.x;
// Higher glow.x gives dimmer glow (because next step is 1 / "angle")
haze_glow = pow(haze_glow, glow.z);
// glow.z should be negative, so we're doing a sort of (1 / "angle") function
// Add "minimum anti-solar illumination"
// For sun, add to glow. For moon, remove glow entirely. SL-13768
haze_glow = (sun_moon_glow_factor < 1.0) ? 0.0 : (haze_glow + 0.25);
vec3 color =
(blue_horizon * blue_weight * (sunlight + ambient_color) + (haze_horizon * haze_weight) * (sunlight * haze_glow + ambient_color));
// Final atmosphere additive
color *= (1. - combined_haze);
// Increase ambient when there are more clouds
vec3 tmpAmbient = ambient_color;
tmpAmbient += max(vec3(0), (1. - ambient_color)) * cloud_shadow * 0.5;
// Dim sunlight by cloud shadow percentage
sunlight *= max(0.0, (1. - cloud_shadow));
// Haze color below cloud
vec3 additiveColorBelowCloud =
(blue_horizon * blue_weight * (sunlight + tmpAmbient) + (haze_horizon * haze_weight) * (sunlight * haze_glow + tmpAmbient));
// Attenuate cloud color by atmosphere
combined_haze = sqrt(combined_haze); // less atmos opacity (more transparency) below clouds
// At horizon, blend high altitude sky color towards the darker color below the clouds
color += (additiveColorBelowCloud - color) * (1. - sqrt(combined_haze));
// Haze color above cloud
vary_HazeColor = color;
}
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