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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
CCL_NAMESPACE_BEGIN
/* Sky texture */
ccl_device float sky_angle_between(float thetav, float phiv, float theta, float phi)
{
float cospsi = sinf(thetav)*sinf(theta)*cosf(phi - phiv) + cosf(thetav)*cosf(theta);
return safe_acosf(cospsi);
}
/*
* "A Practical Analytic Model for Daylight"
* A. J. Preetham, Peter Shirley, Brian Smits
*/
ccl_device float sky_perez_function(float *lam, float theta, float gamma)
{
float ctheta = cosf(theta);
float cgamma = cosf(gamma);
return (1.0f + lam[0]*expf(lam[1]/ctheta)) * (1.0f + lam[2]*expf(lam[3]*gamma) + lam[4]*cgamma*cgamma);
}
ccl_device float3 sky_radiance_old(KernelGlobals *kg, float3 dir,
float sunphi, float suntheta,
float radiance_x, float radiance_y, float radiance_z,
float *config_x, float *config_y, float *config_z)
{
/* convert vector to spherical coordinates */
float2 spherical = direction_to_spherical(dir);
float theta = spherical.x;
float phi = spherical.y;
/* angle between sun direction and dir */
float gamma = sky_angle_between(theta, phi, suntheta, sunphi);
/* clamp theta to horizon */
theta = min(theta, M_PI_2_F - 0.001f);
/* compute xyY color space values */
float x = radiance_y * sky_perez_function(config_y, theta, gamma);
float y = radiance_z * sky_perez_function(config_z, theta, gamma);
float Y = radiance_x * sky_perez_function(config_x, theta, gamma);
/* convert to RGB */
float3 xyz = xyY_to_xyz(x, y, Y);
return xyz_to_rgb(xyz.x, xyz.y, xyz.z);
}
/*
* "An Analytic Model for Full Spectral Sky-Dome Radiance"
* Lukas Hosek, Alexander Wilkie
*/
ccl_device float sky_radiance_internal(float *configuration, float theta, float gamma)
{
float ctheta = cosf(theta);
float cgamma = cosf(gamma);
float expM = expf(configuration[4] * gamma);
float rayM = cgamma * cgamma;
float mieM = (1.0f + rayM) / powf((1.0f + configuration[8]*configuration[8] - 2.0f*configuration[8]*cgamma), 1.5f);
float zenith = sqrtf(ctheta);
return (1.0f + configuration[0] * expf(configuration[1] / (ctheta + 0.01f))) *
(configuration[2] + configuration[3] * expM + configuration[5] * rayM + configuration[6] * mieM + configuration[7] * zenith);
}
ccl_device float3 sky_radiance_new(KernelGlobals *kg, float3 dir,
float sunphi, float suntheta,
float radiance_x, float radiance_y, float radiance_z,
float *config_x, float *config_y, float *config_z)
{
/* convert vector to spherical coordinates */
float2 spherical = direction_to_spherical(dir);
float theta = spherical.x;
float phi = spherical.y;
/* angle between sun direction and dir */
float gamma = sky_angle_between(theta, phi, suntheta, sunphi);
/* clamp theta to horizon */
theta = min(theta, M_PI_2_F - 0.001f);
/* compute xyz color space values */
float x = sky_radiance_internal(config_x, theta, gamma) * radiance_x;
float y = sky_radiance_internal(config_y, theta, gamma) * radiance_y;
float z = sky_radiance_internal(config_z, theta, gamma) * radiance_z;
/* convert to RGB and adjust strength */
return xyz_to_rgb(x, y, z) * (M_2PI_F/683);
}
ccl_device void svm_node_tex_sky(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int *offset)
{
/* Define variables */
float sunphi, suntheta, radiance_x, radiance_y, radiance_z;
float config_x[9], config_y[9], config_z[9];
/* Load data */
uint dir_offset = node.y;
uint out_offset = node.z;
int sky_model = node.w;
float4 data = read_node_float(kg, offset);
sunphi = data.x;
suntheta = data.y;
radiance_x = data.z;
radiance_y = data.w;
data = read_node_float(kg, offset);
radiance_z = data.x;
config_x[0] = data.y;
config_x[1] = data.z;
config_x[2] = data.w;
data = read_node_float(kg, offset);
config_x[3] = data.x;
config_x[4] = data.y;
config_x[5] = data.z;
config_x[6] = data.w;
data = read_node_float(kg, offset);
config_x[7] = data.x;
config_x[8] = data.y;
config_y[0] = data.z;
config_y[1] = data.w;
data = read_node_float(kg, offset);
config_y[2] = data.x;
config_y[3] = data.y;
config_y[4] = data.z;
config_y[5] = data.w;
data = read_node_float(kg, offset);
config_y[6] = data.x;
config_y[7] = data.y;
config_y[8] = data.z;
config_z[0] = data.w;
data = read_node_float(kg, offset);
config_z[1] = data.x;
config_z[2] = data.y;
config_z[3] = data.z;
config_z[4] = data.w;
data = read_node_float(kg, offset);
config_z[5] = data.x;
config_z[6] = data.y;
config_z[7] = data.z;
config_z[8] = data.w;
float3 dir = stack_load_float3(stack, dir_offset);
float3 f;
/* Compute Sky */
if(sky_model == 0)
f = sky_radiance_old(kg, dir, sunphi, suntheta,
radiance_x, radiance_y, radiance_z,
config_x, config_y, config_z);
else
f = sky_radiance_new(kg, dir, sunphi, suntheta,
radiance_x, radiance_y, radiance_z,
config_x, config_y, config_z);
stack_store_float3(stack, out_offset, f);
}
CCL_NAMESPACE_END
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