forked from bartvdbraak/blender
b9ce231060
More information in this post: http://code.blender.org/ Thanks to all contributes for giving their permission!
71 lines
2.3 KiB
C
71 lines
2.3 KiB
C
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License
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*/
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CCL_NAMESPACE_BEGIN
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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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