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void node_volume_principled(vec4 color,
float density,
float anisotropy,
vec4 absorption_color,
float emission_strength,
vec4 emission_color,
float blackbody_intensity,
vec4 blackbody_tint,
float temperature,
float density_attribute,
vec4 color_attribute,
float temperature_attribute,
sampler1DArray spectrummap,
float layer,
out Closure result)
{
#ifdef VOLUMETRICS
vec3 absorption_coeff = vec3(0.0);
vec3 scatter_coeff = vec3(0.0);
vec3 emission_coeff = vec3(0.0);
/* Compute density. */
density = max(density, 0.0);
if (density > 1e-5) {
density = max(density * density_attribute, 0.0);
}
if (density > 1e-5) {
/* Compute scattering and absorption coefficients. */
vec3 scatter_color = color.rgb * color_attribute.rgb;
scatter_coeff = scatter_color * density;
absorption_color.rgb = sqrt(max(absorption_color.rgb, 0.0));
absorption_coeff = max(1.0 - scatter_color, 0.0) * max(1.0 - absorption_color.rgb, 0.0) *
density;
}
/* Compute emission. */
emission_strength = max(emission_strength, 0.0);
if (emission_strength > 1e-5) {
emission_coeff += emission_strength * emission_color.rgb;
}
if (blackbody_intensity > 1e-3) {
/* Add temperature from attribute. */
float T = max(temperature * max(temperature_attribute, 0.0), 0.0);
/* Stefan-Boltzman law. */
float T2 = T * T;
float T4 = T2 * T2;
float sigma = 5.670373e-8 * 1e-6 / M_PI;
float intensity = sigma * mix(1.0, T4, blackbody_intensity);
if (intensity > 1e-5) {
vec4 bb;
node_blackbody(T, spectrummap, layer, bb);
emission_coeff += bb.rgb * blackbody_tint.rgb * intensity;
}
}
result = Closure(absorption_coeff, scatter_coeff, emission_coeff, anisotropy);
#else
result = CLOSURE_DEFAULT;
#endif
}
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