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/**
* @file class3/deferred/genSkyShF.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
* $/LicenseInfo$
*/
#ifdef DEFINE_GL_FRAGCOLOR
out vec4 frag_data[3];
#else
#define frag_data gl_FragData
#endif
VARYING vec2 vary_frag;
uniform vec3 sun_dir;
uniform sampler2D transmittance_texture;
uniform sampler3D scattering_texture;
uniform sampler3D single_mie_scattering_texture;
uniform sampler2D irradiance_texture;
vec3 GetSkyLuminance(vec3 camPos, vec3 view_dir, float shadow_length, vec3 dir, out vec3 transmittance);
vec3 calcDirection(vec2 tc)
{
float phi = tc.y * 2.0 * 3.14159265;
float cosTheta = sqrt(1.0 - tc.x);
float sinTheta = sqrt(1.0 - cosTheta * cosTheta);
return vec3(cos(phi) * sinTheta, sin(phi) * sinTheta, cosTheta);
}
// reverse mapping above to convert a hemisphere direction into phi/theta values
void getPhiAndThetaFromDirection(vec3 dir, out float phi, out float theta)
{
float sin_theta;
float cos_theta;
cos_theta = dir.z;
theta = acos(cos_theta);
sin_theta = sin(theta);
phi = abs(sin_theta) > 0.0001 ? acos(dir.x / sin_theta) : 1.0;
}
// reverse mapping above to convert a hemisphere direction into an SH texture sample pos
vec2 calcShUvFromDirection(vec3 dir)
{
vec2 uv;
float phi;
float theta;
getPhiAndThetaFromDirection(dir, phi, theta);
uv.y = phi / 2.0 * 3.14159265;
uv.x = theta / 2.0 * 3.14159265;
return uv;
}
void projectToL1(vec3 n, vec3 c, vec4 basis, out vec4 coeffs[3])
{
coeffs[0] = vec4(basis.x, n * basis.yzw * c.r);
coeffs[1] = vec4(basis.x, n * basis.yzw * c.g);
coeffs[2] = vec4(basis.x, n * basis.yzw * c.b);
}
void main()
{
float Y00 = sqrt(1.0 / 3.14159265) * 0.5;
float Y1x = sqrt(3.0 / 3.14159265) * 0.5;
float Y1y = Y1x;
float Y1z = Y1x;
vec4 L1 = vec4(Y00, Y1x, Y1y, Y1z);
vec3 view_direction = calcDirection(vary_frag);
vec3 sun_direction = normalize(sun_dir);
vec3 cam_pos = vec3(0, 0, 6360);
vec3 transmittance;
vec3 radiance = GetSkyLuminance(cam_pos, view_direction, 0.0f, sun_direction, transmittance);
vec3 color = vec3(1.0) - exp(-radiance * 0.0001);
color = pow(color, vec3(1.0/2.2));
vec4 coeffs[3];
coeffs[0] = vec4(0);
coeffs[1] = vec4(0);
coeffs[2] = vec4(0);
projectToL1(view_direction, color.rgb, L1, coeffs);
frag_data[0] = coeffs[0];
frag_data[1] = coeffs[1];
frag_data[2] = coeffs[2];
}
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