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/**
* @file WLCloudsV.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
* $/LicenseInfo$
*/
//////////////////////////////////////////////////////////////////////////
// The vertex shader for creating the atmospheric sky
///////////////////////////////////////////////////////////////////////////////
// Output parameters
varying vec4 vary_CloudColorSun;
varying vec4 vary_CloudColorAmbient;
varying float vary_CloudDensity;
// Inputs
uniform vec3 camPosLocal;
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 ambient;
uniform vec4 blue_horizon;
uniform vec4 blue_density;
uniform vec4 haze_horizon;
uniform vec4 haze_density;
uniform vec4 cloud_shadow;
uniform vec4 density_multiplier;
uniform vec4 max_y;
uniform vec4 glow;
uniform vec4 cloud_color;
uniform vec4 cloud_scale;
void main()
{
// World / view / projection
gl_Position = ftransform();
gl_TexCoord[0] = gl_MultiTexCoord0;
// Get relative position
vec3 P = gl_Vertex.xyz - camPosLocal.xyz + vec3(0,50,0);
// Set altitude
if (P.y > 0.)
{
P *= (max_y.x / 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 * 1.0 + haze_density.x * 0.25) * (density_multiplier.x * max_y.x);
// Calculate relative weights
temp1 = blue_density + haze_density.x;
blue_weight = blue_density / temp1;
haze_weight = haze_density.x / 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.x;
// 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;
// Increase ambient when there are more clouds
vec4 tmpAmbient = ambient;
tmpAmbient += (1. - tmpAmbient) * cloud_shadow.x * 0.5;
// Dim sunlight by cloud shadow percentage
sunlight *= (1. - cloud_shadow.x);
// Haze color below cloud
vec4 additiveColorBelowCloud = ( blue_horizon * blue_weight * (sunlight + tmpAmbient)
+ (haze_horizon.r * haze_weight) * (sunlight * temp2.x + tmpAmbient)
);
// CLOUDS
sunlight = sunlight_color;
temp2.y = max(0., lightnorm.y * 2.);
temp2.y = 1. / temp2.y;
sunlight *= exp( - light_atten * temp2.y);
// Cloud color out
vary_CloudColorSun = (sunlight * temp2.x) * cloud_color;
vary_CloudColorAmbient = tmpAmbient * cloud_color;
// Attenuate cloud color by atmosphere
temp1 = sqrt(temp1); //less atmos opacity (more transparency) below clouds
vary_CloudColorSun *= temp1;
vary_CloudColorAmbient *= temp1;
vec4 oHazeColorBelowCloud = additiveColorBelowCloud * (1. - temp1);
// Make a nice cloud density based on the cloud_shadow value that was passed in.
vary_CloudDensity = 2. * (cloud_shadow.x - 0.25);
// Texture coords
gl_TexCoord[0] = gl_MultiTexCoord0;
gl_TexCoord[0].xy -= 0.5;
gl_TexCoord[0].xy /= cloud_scale.x;
gl_TexCoord[0].xy += 0.5;
gl_TexCoord[1] = gl_TexCoord[0];
gl_TexCoord[1].x += lightnorm.x * 0.0125;
gl_TexCoord[1].y += lightnorm.z * 0.0125;
gl_TexCoord[2] = gl_TexCoord[0] * 16.;
gl_TexCoord[3] = gl_TexCoord[1] * 16.;
// Combine these to minimize register use
vary_CloudColorAmbient += oHazeColorBelowCloud;
// needs this to compile on mac
//vary_AtmosAttenuation = vec3(0.0,0.0,0.0);
// END CLOUDS
}
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