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Diffstat (limited to 'intern/cycles/kernel/svm/svm_sky.h')
-rw-r--r-- | intern/cycles/kernel/svm/svm_sky.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/intern/cycles/kernel/svm/svm_sky.h b/intern/cycles/kernel/svm/svm_sky.h new file mode 100644 index 00000000000..dd02cb64cd7 --- /dev/null +++ b/intern/cycles/kernel/svm/svm_sky.h @@ -0,0 +1,92 @@ +/* + * Copyright 2011, Blender Foundation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +CCL_NAMESPACE_BEGIN + +__device float3 xyY_to_xyz(float x, float y, float Y) +{ + float X, Z; + + if(y != 0.0f) X = (x / y) * Y; + else X = 0.0f; + + if(y != 0.0f && Y != 0.0f) Z = (1.0f - x - y) / y * Y; + else Z = 0.0f; + + return make_float3(X, Y, Z); +} + +__device float3 xyz_to_rgb(float x, float y, float z) +{ + return make_float3(3.240479f * x + -1.537150f * y + -0.498535f * z, + -0.969256f * x + 1.875991f * y + 0.041556f * z, + 0.055648f * x + -0.204043f * y + 1.057311f * z); +} + +/* + * "A Practical Analytic Model for Daylight" + * A. J. Preetham, Peter Shirley, Brian Smits + */ + +__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); +} + +__device float sky_perez_function(float lam[5], 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); +} + +__device float3 sky_radiance(KernelGlobals *kg, float3 dir) +{ + /* 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, kernel_data.sunsky.theta, kernel_data.sunsky.phi); + + /* clamp theta to horizon */ + theta = min(theta, M_PI_2_F - 0.001f); + + /* compute xyY color space values */ + float x = kernel_data.sunsky.zenith_x * sky_perez_function(kernel_data.sunsky.perez_x, theta, gamma); + float y = kernel_data.sunsky.zenith_y * sky_perez_function(kernel_data.sunsky.perez_y, theta, gamma); + float Y = kernel_data.sunsky.zenith_Y * sky_perez_function(kernel_data.sunsky.perez_Y, theta, gamma); + + /* convert to RGB */ + float3 xyz = xyY_to_xyz(x, y, Y); + return xyz_to_rgb(xyz.x, xyz.y, xyz.z); +} + +__device void svm_node_tex_sky(KernelGlobals *kg, ShaderData *sd, float *stack, uint dir_offset, uint out_offset) +{ + float3 dir = stack_load_float3(stack, dir_offset); + float3 f = sky_radiance(kg, dir); + + stack_store_float3(stack, out_offset, f); +} + +CCL_NAMESPACE_END + |