Spectrum VolumeRegion::sigma_t(const Point &p, const Vector &w) const { return sigma_a(p, w) + sigma_s(p, w); }
Spectrum VolumeRegion::sigma_t(const Point &p, const Vector &w, float time) const { return sigma_a(p, w, time) + sigma_s(p, w, time); }
real Medium::sigma_t(const glm::vec3 & point) const { return sigma_a(point) + sigma_s(point); }