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/**
* Precomputed Atmospheric Scattering
* Copyright (c) 2008 INRIA
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Author: Eric Bruneton
*/
// computes ground irradiance due to skylight E[deltaS] (line 8 in algorithm 4.1)
uniform sampler3D deltaSRSampler;
uniform sampler3D deltaSMSampler;
uniform float first;
#ifdef _VERTEX_
void main() {
gl_Position = gl_Vertex;
}
#endif
#ifdef _FRAGMENT_
const float dphi = M_PI / float(IRRADIANCE_INTEGRAL_SAMPLES);
const float dtheta = M_PI / float(IRRADIANCE_INTEGRAL_SAMPLES);
void main() {
float r, muS;
getIrradianceRMuS(r, muS);
vec3 s = vec3(ieeesqrt(1.0 - muS * muS), 0.0, muS);
vec3 result = vec3(0.0);
// integral over 2.PI around x with two nested loops over w directions (theta,phi) -- Eq (15)
for (int iphi = 0; iphi < 2 * IRRADIANCE_INTEGRAL_SAMPLES; ++iphi) {
float phi = (float(iphi) + 0.5) * dphi;
for (int itheta = 0; itheta < IRRADIANCE_INTEGRAL_SAMPLES / 2; ++itheta) {
float theta = (float(itheta) + 0.5) * dtheta;
float dw = dtheta * dphi * sin(theta);
vec3 w = vec3(cos(phi) * sin(theta), sin(phi) * sin(theta), cos(theta));
float nu = dot(s, w);
if (first == 1.0) {
// first iteration is special because Rayleigh and Mie were stored separately,
// without the phase functions factors; they must be reintroduced here
float pr1 = phaseFunctionR(nu);
float pm1 = phaseFunctionM(nu);
vec3 ray1 = texture4D(deltaSRSampler, r, w.z, muS, nu).rgb;
vec3 mie1 = texture4D(deltaSMSampler, r, w.z, muS, nu).rgb;
result += (ray1 * pr1 + mie1 * pm1) * w.z * dw;
} else {
result += texture4D(deltaSRSampler, r, w.z, muS, nu).rgb * w.z * dw;
}
}
}
gl_FragColor = vec4(result, 0.0);
}
#endif
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