[Bf-blender-cvs] [49ed792a789] principled-v2: Clean up existing fresnel handling
Lukas Stockner
noreply at git.blender.org
Mon Jul 4 23:56:11 CEST 2022
Commit: 49ed792a7890cd473d42ba33d94bc4a773e99e77
Author: Lukas Stockner
Date: Mon Jul 4 23:31:47 2022 +0200
Branches: principled-v2
https://developer.blender.org/rB49ed792a7890cd473d42ba33d94bc4a773e99e77
Clean up existing fresnel handling
===================================================================
M intern/cycles/kernel/closure/bsdf_microfacet.h
M intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h
M intern/cycles/kernel/closure/bsdf_util.h
===================================================================
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h
index 29b0e4b3046..42ea71f62a9 100644
--- a/intern/cycles/kernel/closure/bsdf_microfacet.h
+++ b/intern/cycles/kernel/closure/bsdf_microfacet.h
@@ -39,16 +39,16 @@ ccl_device_forceinline float3 reflection_color(ccl_private const MicrofacetBsdf
float3 L,
float3 H)
{
- float3 F = make_float3(1.0f, 1.0f, 1.0f);
- bool use_fresnel = (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_FRESNEL_ID ||
- bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID);
- if (use_fresnel) {
- float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior);
-
- F = interpolate_fresnel_color(L, H, bsdf->ior, F0, bsdf->extra->cspec0);
+ if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_FRESNEL_ID) {
+ return interpolate_fresnel_color(L, H, bsdf->ior, bsdf->extra->cspec0);
+ }
+ else if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
+ return 0.25f * interpolate_fresnel_color(L, H, bsdf->ior, bsdf->extra->cspec0) *
+ bsdf->extra->clearcoat;
+ }
+ else {
+ return one_float3();
}
-
- return F;
}
ccl_device_forceinline void bsdf_microfacet_fresnel_color(ccl_private const ShaderData *sd,
@@ -56,9 +56,8 @@ ccl_device_forceinline void bsdf_microfacet_fresnel_color(ccl_private const Shad
{
kernel_assert(CLOSURE_IS_BSDF_MICROFACET_FRESNEL(bsdf->type));
- float F0 = fresnel_dielectric_cos(1.0f, bsdf->ior);
bsdf->extra->fresnel_color = interpolate_fresnel_color(
- sd->I, bsdf->N, bsdf->ior, F0, bsdf->extra->cspec0);
+ sd->I, bsdf->N, bsdf->ior, bsdf->extra->cspec0);
if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
bsdf->extra->fresnel_color *= 0.25f * bsdf->extra->clearcoat;
@@ -295,9 +294,6 @@ ccl_device float3 bsdf_microfacet_ggx_eval_reflect(ccl_private const ShaderClosu
float common = D * 0.25f / cosNO;
float3 F = reflection_color(bsdf, omega_in, m);
- if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
- F *= 0.25f * bsdf->extra->clearcoat;
- }
float3 out = F * common / (1 + lambdaO + lambdaI);
*pdf = common / (1 + lambdaO);
@@ -409,18 +405,11 @@ ccl_device int bsdf_microfacet_ggx_sample(ccl_private const ShaderClosure *sc,
*omega_in = 2 * cosMO * m - I;
if (dot(Ng, *omega_in) > 0) {
+ float3 F = reflection_color(bsdf, *omega_in, m);
if (alpha_x * alpha_y <= 1e-7f) {
/* Specular case, just return some high number for MIS */
*pdf = 1e6f;
- *eval = make_float3(1e6f, 1e6f, 1e6f);
-
- bool use_fresnel = (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_FRESNEL_ID ||
- bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID);
-
- /* if fresnel is used, calculate the color with reflection_color(...) */
- if (use_fresnel) {
- *eval *= reflection_color(bsdf, *omega_in, m);
- }
+ *eval = make_float3(1e6f, 1e6f, 1e6f) * F;
label = LABEL_REFLECT | LABEL_SINGULAR;
}
@@ -465,15 +454,9 @@ ccl_device int bsdf_microfacet_ggx_sample(ccl_private const ShaderClosure *sc,
float common = D * 0.25f / cosNO;
*pdf = common / (1 + lambdaO);
- float3 F = reflection_color(bsdf, *omega_in, m);
-
*eval = common * F / (1 + lambdaO + lambdaI);
}
- if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
- *eval *= 0.25f * bsdf->extra->clearcoat;
- }
-
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = (2 * dot(m, dIdx)) * m - dIdx;
*domega_in_dy = (2 * dot(m, dIdy)) * m - dIdy;
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h b/intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h
index e4fcf0e6ba3..539853aab16 100644
--- a/intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h
+++ b/intern/cycles/kernel/closure/bsdf_microfacet_multi_impl.h
@@ -73,9 +73,8 @@ ccl_device_forceinline float3 MF_FUNCTION_FULL_NAME(mf_eval)(float3 wi,
eval = make_float3(val, val, val);
#endif
- float F0 = fresnel_dielectric_cos(1.0f, eta);
if (use_fresnel) {
- throughput = interpolate_fresnel_color(wi, wh, eta, F0, cspec0);
+ throughput = interpolate_fresnel_color(wi, wh, eta, cspec0);
eval *= throughput;
}
@@ -144,11 +143,11 @@ ccl_device_forceinline float3 MF_FUNCTION_FULL_NAME(mf_eval)(float3 wi,
throughput *= color;
}
else if (use_fresnel && order > 0) {
- throughput *= interpolate_fresnel_color(wi_prev, wm, eta, F0, cspec0);
+ throughput *= interpolate_fresnel_color(wi_prev, wm, eta, cspec0);
}
#else /* MF_MULTI_GLOSSY */
if (use_fresnel && order > 0) {
- throughput *= interpolate_fresnel_color(-wr, wm, eta, F0, cspec0);
+ throughput *= interpolate_fresnel_color(-wr, wm, eta, cspec0);
}
wr = mf_sample_phase_glossy(-wr, &throughput, wm);
#endif
@@ -192,8 +191,6 @@ ccl_device_forceinline float3 MF_FUNCTION_FULL_NAME(mf_sample)(float3 wi,
float G1_r = 0.0f;
bool outside = true;
- float F0 = fresnel_dielectric_cos(1.0f, eta);
-
int order;
for (order = 0; order < 10; order++) {
/* Sample microfacet height. */
@@ -229,7 +226,7 @@ ccl_device_forceinline float3 MF_FUNCTION_FULL_NAME(mf_sample)(float3 wi,
throughput *= color;
}
else {
- float3 t_color = interpolate_fresnel_color(wi_prev, wm, eta, F0, cspec0);
+ float3 t_color = interpolate_fresnel_color(wi_prev, wm, eta, cspec0);
if (order == 0)
throughput = t_color;
@@ -239,7 +236,7 @@ ccl_device_forceinline float3 MF_FUNCTION_FULL_NAME(mf_sample)(float3 wi,
}
#else /* MF_MULTI_GLOSSY */
if (use_fresnel) {
- float3 t_color = interpolate_fresnel_color(-wr, wm, eta, F0, cspec0);
+ float3 t_color = interpolate_fresnel_color(-wr, wm, eta, cspec0);
if (order == 0)
throughput = t_color;
diff --git a/intern/cycles/kernel/closure/bsdf_util.h b/intern/cycles/kernel/closure/bsdf_util.h
index e3b24d487f1..a1541a01cd5 100644
--- a/intern/cycles/kernel/closure/bsdf_util.h
+++ b/intern/cycles/kernel/closure/bsdf_util.h
@@ -109,19 +109,17 @@ ccl_device float schlick_fresnel(float u)
return m2 * m2 * m; // pow(m, 5)
}
-/* Calculate the fresnel color which is a blend between white and the F0 color (cspec0) */
+/* Calculate the fresnel color which is a blend between white and the F0 color */
ccl_device_forceinline float3
-interpolate_fresnel_color(float3 L, float3 H, float ior, float F0, float3 cspec0)
+interpolate_fresnel_color(float3 L, float3 H, float ior, float3 F0)
{
- /* Calculate the fresnel interpolation factor
- * The value from fresnel_dielectric_cos(...) has to be normalized because
- * the cspec0 keeps the F0 color
- */
- float F0_norm = 1.0f / (1.0f - F0);
- float FH = (fresnel_dielectric_cos(dot(L, H), ior) - F0) * F0_norm;
+ /* Compute the real Fresnel term and remap it from real_F0...1 to F0...1.
+ * We could also just use actual Schlick fresnel (lerp(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;
- /* Blend between white and a specular color with respect to the fresnel */
- return cspec0 * (1.0f - FH) + make_float3(1.0f, 1.0f, 1.0f) * FH;
+ return lerp(F0, one_float3(), FH);
}
ccl_device float3 ensure_valid_reflection(float3 Ng, float3 I, float3 N)
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