forked from bartvdbraak/blender
93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
/*
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* Copyright 2011, Blender Foundation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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CCL_NAMESPACE_BEGIN
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__device float3 xyY_to_xyz(float x, float y, float Y)
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{
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float X, Z;
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if(y != 0.0f) X = (x / y) * Y;
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else X = 0.0f;
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if(y != 0.0f && Y != 0.0f) Z = (1.0f - x - y) / y * Y;
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else Z = 0.0f;
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return make_float3(X, Y, Z);
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}
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__device float3 xyz_to_rgb(float x, float y, float z)
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{
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return make_float3(3.240479f * x + -1.537150f * y + -0.498535f * z,
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-0.969256f * x + 1.875991f * y + 0.041556f * z,
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0.055648f * x + -0.204043f * y + 1.057311f * z);
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}
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/*
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* "A Practical Analytic Model for Daylight"
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* A. J. Preetham, Peter Shirley, Brian Smits
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*/
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__device float sky_angle_between(float thetav, float phiv, float theta, float phi)
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{
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float cospsi = sinf(thetav)*sinf(theta)*cosf(phi - phiv) + cosf(thetav)*cosf(theta);
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return safe_acosf(cospsi);
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}
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__device float sky_perez_function(__constant float *lam, float theta, float gamma)
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{
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float ctheta = cosf(theta);
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float cgamma = cosf(gamma);
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return (1.0f + lam[0]*expf(lam[1]/ctheta)) * (1.0f + lam[2]*expf(lam[3]*gamma) + lam[4]*cgamma*cgamma);
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}
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__device float3 sky_radiance(KernelGlobals *kg, float3 dir)
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{
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/* convert vector to spherical coordinates */
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float2 spherical = direction_to_spherical(dir);
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float theta = spherical.x;
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float phi = spherical.y;
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/* angle between sun direction and dir */
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float gamma = sky_angle_between(theta, phi, kernel_data.sunsky.theta, kernel_data.sunsky.phi);
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/* clamp theta to horizon */
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theta = min(theta, M_PI_2_F - 0.001f);
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/* compute xyY color space values */
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float x = kernel_data.sunsky.zenith_x * sky_perez_function(kernel_data.sunsky.perez_x, theta, gamma);
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float y = kernel_data.sunsky.zenith_y * sky_perez_function(kernel_data.sunsky.perez_y, theta, gamma);
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float Y = kernel_data.sunsky.zenith_Y * sky_perez_function(kernel_data.sunsky.perez_Y, theta, gamma);
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/* convert to RGB */
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float3 xyz = xyY_to_xyz(x, y, Y);
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return xyz_to_rgb(xyz.x, xyz.y, xyz.z);
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}
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__device void svm_node_tex_sky(KernelGlobals *kg, ShaderData *sd, float *stack, uint dir_offset, uint out_offset)
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{
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float3 dir = stack_load_float3(stack, dir_offset);
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float3 f = sky_radiance(kg, dir);
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stack_store_float3(stack, out_offset, f);
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}
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CCL_NAMESPACE_END
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