diff options
Diffstat (limited to 'intern/cycles/kernel/osl/nodes/node_sky_texture.osl')
| -rw-r--r-- | intern/cycles/kernel/osl/nodes/node_sky_texture.osl | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/intern/cycles/kernel/osl/nodes/node_sky_texture.osl b/intern/cycles/kernel/osl/nodes/node_sky_texture.osl new file mode 100644 index 00000000000..fdb9b1d9708 --- /dev/null +++ b/intern/cycles/kernel/osl/nodes/node_sky_texture.osl @@ -0,0 +1,162 @@ +/* + * 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. + */ + +#include "stdosl.h" + +struct KernelSunSky { + /* sun direction in spherical and cartesian */ + float theta, phi; + vector dir; + + /* perez function parameters */ + float zenith_Y, zenith_x, zenith_y; + float perez_Y[5], perez_x[5], perez_y[5]; +}; + +color xyY_to_xyz(float x, float y, float Y) +{ + float X, Z; + + if(y != 0.0) X = (x / y) * Y; + else X = 0.0; + + if(y != 0.0 && Y != 0.0) Z = ((1.0 - x - y) / y) * Y; + else Z = 0.0; + + return color(X, Y, Z); +} + +color xyz_to_rgb(float x, float y, float z) +{ + return color(3.240479 * x + -1.537150 * y + -0.498535 * z, + -0.969256 * x + 1.875991 * y + 0.041556 * z, + 0.055648 * x + -0.204043 * y + 1.057311 * z); +} + +float sky_angle_between(float thetav, float phiv, float theta, float phi) +{ + float cospsi = sin(thetav)*sin(theta)*cos(phi - phiv) + cos(thetav)*cos(theta); + + if(cospsi > 1.0) + return 0.0; + if(cospsi < -1.0) + return M_PI; + + return acos(cospsi); +} + +vector sky_spherical_coordinates(vector dir) +{ + return vector(acos(dir[2]), atan2(dir[0], dir[1]), 0); +} + +float sky_perez_function(float lam[5], float theta, float gamma) +{ + float ctheta = cos(theta); + float cgamma = cos(gamma); + + return (1.0 + lam[0]*exp(lam[1] / ctheta)) * (1.0 + lam[2]*exp(lam[3]*gamma) + lam[4]*cgamma*cgamma); +} + +color sky_xyz_radiance(KernelSunSky sunsky, vector dir) +{ + /* convert vector to spherical coordinates */ + vector spherical = sky_spherical_coordinates(dir); + float theta = spherical[0]; + float phi = spherical[1]; + + /* angle between sun direction and dir */ + float gamma = sky_angle_between(theta, phi, sunsky.theta, sunsky.phi); + + /* clamp theta to horizon */ + theta = min(theta, M_PI_2 - 0.001); + + /* compute xyY color space values */ + float x = sunsky.zenith_x * sky_perez_function(sunsky.perez_x, theta, gamma); + float y = sunsky.zenith_y * sky_perez_function(sunsky.perez_y, theta, gamma); + float Y = sunsky.zenith_Y * sky_perez_function(sunsky.perez_Y, theta, gamma); + + /* convert to RGB */ + color xyz = xyY_to_xyz(x, y, Y); + return xyz_to_rgb(xyz[0], xyz[1], xyz[2]); +} + +void precompute_sunsky(vector dir, float turbidity, output KernelSunSky sunsky) +{ + vector spherical = sky_spherical_coordinates(dir); + float theta = spherical[0]; + float phi = spherical[1]; + + sunsky.theta = theta; + sunsky.phi = phi; + sunsky.dir = dir; + + float theta2 = theta*theta; + float theta3 = theta*theta*theta; + float T = turbidity; + float T2 = T*T; + + float chi = (4.0/ 9.0- T / 120.0) * (M_PI - 2.0* theta); + sunsky.zenith_Y = (4.0453*T - 4.9710) * tan(chi) - 0.2155*T + 2.4192; + sunsky.zenith_Y *= 0.06; + + sunsky.zenith_x = + (0.00166* theta3 - 0.00375* theta2 + 0.00209* theta)*T2 + + (-0.02903* theta3 + 0.06377* theta2 - 0.03202* theta + 0.00394)*T + + (0.11693* theta3 - 0.21196* theta2 + 0.06052* theta + 0.25886); + + sunsky.zenith_y = + (0.00275* theta3 - 0.00610* theta2 + 0.00317* theta)*T2 + + (-0.04214* theta3 + 0.08970* theta2 - 0.04153* theta + 0.00516)*T + + (0.15346* theta3 - 0.26756* theta2 + 0.06670* theta + 0.26688); + + sunsky.perez_Y[0] = (0.1787*T - 1.4630); + sunsky.perez_Y[1] = (-0.3554*T + 0.4275); + sunsky.perez_Y[2] = (-0.0227*T + 5.3251); + sunsky.perez_Y[3] = (0.1206*T - 2.5771); + sunsky.perez_Y[4] = (-0.0670*T + 0.3703); + + sunsky.perez_x[0] = (-0.0193*T - 0.2592); + sunsky.perez_x[1] = (-0.0665*T + 0.0008); + sunsky.perez_x[2] = (-0.0004*T + 0.2125); + sunsky.perez_x[3] = (-0.0641*T - 0.8989); + sunsky.perez_x[4] = (-0.0033*T + 0.0452); + + sunsky.perez_y[0] = (-0.0167*T - 0.2608); + sunsky.perez_y[1] = (-0.0950*T + 0.0092); + sunsky.perez_y[2] = (-0.0079*T + 0.2102); + sunsky.perez_y[3] = (-0.0441*T - 1.6537); + sunsky.perez_y[4] = (-0.0109*T + 0.0529); + + sunsky.zenith_Y /= sky_perez_function(sunsky.perez_Y, 0, theta); + sunsky.zenith_x /= sky_perez_function(sunsky.perez_x, 0, theta); + sunsky.zenith_y /= sky_perez_function(sunsky.perez_y, 0, theta); +} + +shader node_sky_texture( + vector Vector = P, + vector sun_direction = vector(0, 0, 1), + float turbidity = 2.2, + output color Color = color(0.0, 0.0, 0.0)) +{ + KernelSunSky sunsky; + + precompute_sunsky(sun_direction, turbidity, sunsky); + Color = sky_xyz_radiance(sunsky, Vector); +} + |