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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 "stdosl.h"
shader node_principled_volume(
color Color = color(0.5, 0.5, 0.5),
float Density = 1.0,
float Anisotropy = 0.0,
color AbsorptionColor = color(0.0, 0.0, 0.0),
float EmissionStrength = 0.0,
color EmissionColor = color(1.0, 1.0, 1.0),
float BlackbodyIntensity = 0.0,
color BlackbodyTint = color(1.0, 1.0, 1.0),
float Temperature = 1500.0,
string DensityAttribute = "geom:density",
string ColorAttribute = "geom:color",
string TemperatureAttribute = "geom:temperature",
output closure color Volume = 0)
{
/* Compute density. */
float primitive_density = 1.0;
float density = max(Density, 0.0);
if(density > 1e-5) {
if(getattribute(DensityAttribute, primitive_density)) {
density = max(density * primitive_density, 0.0);
}
}
if(density > 1e-5) {
/* Compute scattering color. */
color scatter_color = Color;
color primitive_color;
if(getattribute(ColorAttribute, primitive_color)) {
scatter_color *= primitive_color;
}
/* Add scattering and absorption closures. */
color scatter_coeff = scatter_color;
color absorption_color = sqrt(max(AbsorptionColor, 0.0));
color absorption_coeff = max(1.0 - scatter_color, 0.0) * max(1.0 - absorption_color, 0.0);
Volume = scatter_coeff * density * henyey_greenstein(Anisotropy) +
absorption_coeff * density * absorption();
}
/* Compute emission. */
float emission_strength = max(EmissionStrength, 0.0);
float blackbody_intensity = BlackbodyIntensity;
if(emission_strength > 1e-5) {
Volume += emission_strength * EmissionColor * emission();
}
if(blackbody_intensity > 1e-3) {
float T = Temperature;
/* Add temperature from attribute if available. */
float temperature;
if(getattribute(TemperatureAttribute, temperature)) {
T *= max(temperature, 0.0);
}
T = max(T, 0.0);
/* Stefan-Boltzman law. */
float T4 = (T * T) * (T * T);
float sigma = 5.670373e-8 * 1e-6 / M_PI;
float intensity = sigma * mix(1.0, T4, blackbody_intensity);
if(intensity > 1e-5) {
color bb = blackbody(T);
float l = luminance(bb);
if(l != 0.0) {
bb *= BlackbodyTint * intensity / l;
Volume += bb * emission();
}
}
}
}
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