diff options
Diffstat (limited to 'intern/cycles/kernel/closure/bsdf_util.h')
-rw-r--r-- | intern/cycles/kernel/closure/bsdf_util.h | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/intern/cycles/kernel/closure/bsdf_util.h b/intern/cycles/kernel/closure/bsdf_util.h index 13de4ac15b0..47a37a43c87 100644 --- a/intern/cycles/kernel/closure/bsdf_util.h +++ b/intern/cycles/kernel/closure/bsdf_util.h @@ -71,6 +71,13 @@ ccl_device float fresnel_dielectric_cos(float cosi, float eta) return 1.0f; // TIR(no refracted component) } +/* Returns F0 (perpendicular) reflectivity for given eta, + * equivalent to fresnel_dielectric_cos(1.0f, eta). */ +ccl_device float fresnel_dielectric_F0(float eta) +{ + return sqr((eta - 1.0f) / (eta + 1.0f)); +} + ccl_device Spectrum fresnel_conductor(float cosi, const Spectrum eta, const Spectrum k) { Spectrum cosi2 = make_spectrum(sqr(cosi)); @@ -124,11 +131,9 @@ ccl_device_forceinline Spectrum interpolate_fresnel_color(Spectrum L, { /* Compute the real Fresnel term and remap it from real_F0...1 to F0...1. * We could also just use actual Schlick fresnel (mix(F0, 1, (1-cosI)^5)) here. */ - float real_F0 = fresnel_dielectric_cos(1.0f, ior); - float F0_norm = 1.0f / (1.0f - real_F0); - float FH = (fresnel_dielectric_cos(dot(L, H), ior) - real_F0) * F0_norm; - - return mix(F0, one_spectrum(), FH); + float real_F0 = fresnel_dielectric_F0(ior); + float mixFactor = inverse_lerp(real_F0, 1.0f, fresnel_dielectric_cos(dot(L, H), ior)); + return mix(F0, one_spectrum(), mixFactor); } ccl_device float3 ensure_valid_reflection(float3 Ng, float3 I, float3 N) |