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/**
* @file WLSkyV.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 vec4 vary_HazeColor;
// Inputs
uniform vec3 camPosLocal;
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 ambient;
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 max_y;
uniform vec4 glow;
uniform vec4 cloud_color;
void main()
{
// World / view / projection
gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
// Get relative position
vec3 P = position.xyz - camPosLocal.xyz + vec3(0,50,0);
//vec3 P = position.xyz + vec3(0,50,0);
// Set altitude
if (P.y > 0.)
{
P *= (max_y / P.y);
}
else
{
P *= (-32000. / P.y);
}
// Can normalize then
vec3 Pn = normalize(P);
float Plen = length(P);
// Initialize temp variables
vec4 temp1 = vec4(0.);
vec4 temp2 = vec4(0.);
vec4 blue_weight;
vec4 haze_weight;
vec4 sunlight = sunlight_color;
vec4 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 + vec4(haze_density * 0.25)) * (density_multiplier * max_y);
// Calculate relative weights
temp1 = blue_density + haze_density;
blue_weight = blue_density / temp1;
haze_weight = haze_density / temp1;
// Compute sunlight from P & lightnorm (for long rays like sky)
temp2.y = max(0., max(0., Pn.y) * 1.0 + lightnorm.y );
temp2.y = 1. / temp2.y;
sunlight *= exp( - light_atten * temp2.y);
// Distance
temp2.z = Plen * density_multiplier;
// Transparency (-> temp1)
// ATI Bugfix -- can't store temp1*temp2.z in a variable because the ati
// compiler gets confused.
temp1 = exp(-temp1 * temp2.z);
// Compute haze glow
temp2.x = dot(Pn, lightnorm.xyz);
temp2.x = 1. - temp2.x;
// temp2.x is 0 at the sun and increases away from sun
temp2.x = max(temp2.x, .001);
// 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;
// Haze color above cloud
vary_HazeColor = ( blue_horizon * blue_weight * (sunlight + ambient)
+ (haze_horizon * haze_weight) * (sunlight * temp2.x + ambient)
);
// Increase ambient when there are more clouds
vec4 tmpAmbient = ambient;
tmpAmbient += (1. - tmpAmbient) * cloud_shadow * 0.5;
// Dim sunlight by cloud shadow percentage
sunlight *= (1. - cloud_shadow);
// Haze color below cloud
vec4 additiveColorBelowCloud = ( blue_horizon * blue_weight * (sunlight + tmpAmbient)
+ (haze_horizon * haze_weight) * (sunlight * temp2.x + tmpAmbient)
);
// Final atmosphere additive
vary_HazeColor *= (1. - temp1);
// Attenuate cloud color by atmosphere
temp1 = sqrt(temp1); //less atmos opacity (more transparency) below clouds
// At horizon, blend high altitude sky color towards the darker color below the clouds
vary_HazeColor += (additiveColorBelowCloud - vary_HazeColor) * (1. - sqrt(temp1));
// won't compile on mac without this being set
//vary_AtmosAttenuation = vec3(0.0,0.0,0.0);
}
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