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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.
*/
#include "node_color.h"
#include "stdcycles.h"
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);
}
/* Preetham */
float sky_perez_function(float lam[9], 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_radiance_preetham(normal dir,
float sunphi,
float suntheta,
color radiance,
float config_x[9],
float config_y[9],
float config_z[9])
{
/* 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, suntheta, sunphi);
/* clamp theta to horizon */
theta = min(theta, M_PI_2 - 0.001);
/* compute xyY color space values */
float x = radiance[1] * sky_perez_function(config_y, theta, gamma);
float y = radiance[2] * sky_perez_function(config_z, theta, gamma);
float Y = radiance[0] * sky_perez_function(config_x, theta, gamma);
/* convert to RGB */
color xyz = xyY_to_xyz(x, y, Y);
return xyz_to_rgb(xyz[0], xyz[1], xyz[2]);
}
/* Hosek / Wilkie */
float sky_radiance_internal(float config[9], float theta, float gamma)
{
float ctheta = cos(theta);
float cgamma = cos(gamma);
float expM = exp(config[4] * gamma);
float rayM = cgamma * cgamma;
float mieM = (1.0 + rayM) / pow((1.0 + config[8] * config[8] - 2.0 * config[8] * cgamma), 1.5);
float zenith = sqrt(ctheta);
return (1.0 + config[0] * exp(config[1] / (ctheta + 0.01))) *
(config[2] + config[3] * expM + config[5] * rayM + config[6] * mieM + config[7] * zenith);
}
color sky_radiance_hosek(normal dir,
float sunphi,
float suntheta,
color radiance,
float config_x[9],
float config_y[9],
float config_z[9])
{
/* 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, suntheta, sunphi);
/* clamp theta to horizon */
theta = min(theta, M_PI_2 - 0.001);
/* compute xyz color space values */
float x = sky_radiance_internal(config_x, theta, gamma) * radiance[0];
float y = sky_radiance_internal(config_y, theta, gamma) * radiance[1];
float z = sky_radiance_internal(config_z, theta, gamma) * radiance[2];
/* convert to RGB and adjust strength */
return xyz_to_rgb(x, y, z) * (M_2PI / 683);
}
/* Nishita improved */
vector geographical_to_direction(float lat, float lon)
{
return vector(cos(lat) * cos(lon), cos(lat) * sin(lon), sin(lat));
}
float precise_angle(vector a, vector b)
{
return 2.0 * atan2(length(a - b), length(a + b));
}
color sky_radiance_nishita(vector dir, float nishita_data[10], string filename)
{
/* definitions */
float sun_elevation = nishita_data[6];
float sun_rotation = nishita_data[7];
float angular_diameter = nishita_data[8];
float sun_intensity = nishita_data[9];
int sun_disc = angular_diameter > 0;
float alpha = 1.0;
color xyz;
/* convert dir to spherical coordinates */
vector direction = sky_spherical_coordinates(dir);
/* render above the horizon */
if (dir[2] >= 0.0) {
/* definitions */
vector sun_dir = geographical_to_direction(sun_elevation, sun_rotation + M_PI_2);
float sun_dir_angle = precise_angle(dir, sun_dir);
float half_angular = angular_diameter / 2.0;
float dir_elevation = M_PI_2 - direction[0];
/* if ray inside sun disc render it, otherwise render sky */
if (sun_dir_angle < half_angular && sun_disc == 1) {
/* get 2 pixels data */
color pixel_bottom = color(nishita_data[0], nishita_data[1], nishita_data[2]);
color pixel_top = color(nishita_data[3], nishita_data[4], nishita_data[5]);
float y;
/* sun interpolation */
if (sun_elevation - half_angular > 0.0) {
if ((sun_elevation + half_angular) > 0.0) {
y = ((dir_elevation - sun_elevation) / angular_diameter) + 0.5;
xyz = mix(pixel_bottom, pixel_top, y) * sun_intensity;
}
}
else {
if (sun_elevation + half_angular > 0.0) {
y = dir_elevation / (sun_elevation + half_angular);
xyz = mix(pixel_bottom, pixel_top, y) * sun_intensity;
}
}
/* limb darkening, coefficient is 0.6f */
float angle_fraction = sun_dir_angle / half_angular;
float limb_darkening = (1.0 - 0.6 * (1.0 - sqrt(1.0 - angle_fraction * angle_fraction)));
xyz *= limb_darkening;
}
/* sky */
else {
/* sky interpolation */
float x = (direction[1] + M_PI + sun_rotation) / M_2PI;
/* more pixels toward horizon compensation */
float y = 1.0 - sqrt(dir_elevation / M_PI_2);
if (x > 1.0) {
x = x - 1.0;
}
xyz = (color)texture(filename, x, y, "wrap", "clamp", "interp", "linear", "alpha", alpha);
}
}
/* ground */
else {
if (dir[2] < -0.4) {
xyz = color(0, 0, 0);
}
else {
/* black ground fade */
float mul = pow(1.0 + dir[2] * 2.5, 3.0);
/* interpolation */
float x = (direction[1] + M_PI + sun_rotation) / M_2PI;
float y = 1.5;
if (x > 1.0) {
x = x - 1.0;
}
xyz = (color)texture(
filename, x, y, "wrap", "periodic", "interp", "linear", "alpha", alpha) *
mul;
}
}
/* convert to RGB */
return xyz_to_rgb(xyz[0], xyz[1], xyz[2]);
}
shader node_sky_texture(
int use_mapping = 0,
matrix mapping = matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
vector Vector = P,
string sky_type = "hosek_wilkie",
float theta = 0.0,
float phi = 0.0,
string filename = "",
color radiance = color(0.0, 0.0, 0.0),
float config_x[9] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
float config_y[9] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
float config_z[9] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
float nishita_data[10] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0},
output color Color = color(0.0, 0.0, 0.0))
{
vector p = Vector;
if (use_mapping)
p = transform(mapping, p);
if (sky_type == "nishita_improved")
Color = sky_radiance_nishita(p, nishita_data, filename);
if (sky_type == "hosek_wilkie")
Color = sky_radiance_hosek(p, phi, theta, radiance, config_x, config_y, config_z);
if (sky_type == "preetham")
Color = sky_radiance_preetham(p, phi, theta, radiance, config_x, config_y, config_z);
}
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