Cycles: BSDF eval refactor to remove separate reflection/refraction methods

Simplifies code overall to do it inside the eval function, most of the BSDFs
already compute the dot product.

The refactoring in bsdf_principled_hair_eval() was needed to avoid a HIP
compiler bug. Cause is unclear, just changing the implementation enough
is meant to sidestep it.

Ref T92571, D15286

1 files changed, 12 insertions, 14 deletions

diff --git a/intern/cycles/kernel/closure/bsdf_diffuse_ramp.h b/intern/cycles/kernel/closure/bsdf_diffuse_ramp.h
index d7faf5c9e9a..e955ed00b92 100644
--- a/intern/cycles/kernel/closure/bsdf_diffuse_ramp.h
+++ b/intern/cycles/kernel/closure/bsdf_diffuse_ramp.h
@@ -47,25 +47,23 @@ ccl_device void bsdf_diffuse_ramp_blur(ccl_private ShaderClosure *sc, float roug
 {
 }
 
-ccl_device Spectrum bsdf_diffuse_ramp_eval_reflect(ccl_private const ShaderClosure *sc,
-                                                   const float3 I,
-                                                   const float3 omega_in,
-                                                   ccl_private float *pdf)
+ccl_device Spectrum bsdf_diffuse_ramp_eval(ccl_private const ShaderClosure *sc,
+                                           const float3 I,
+                                           const float3 omega_in,
+                                           ccl_private float *pdf)
 {
   const DiffuseRampBsdf *bsdf = (const DiffuseRampBsdf *)sc;
   float3 N = bsdf->N;
 
   float cos_pi = fmaxf(dot(N, omega_in), 0.0f);
-  *pdf = cos_pi * M_1_PI_F;
-  return rgb_to_spectrum(bsdf_diffuse_ramp_get_color(bsdf->colors, cos_pi) * M_1_PI_F);
-}
-
-ccl_device Spectrum bsdf_diffuse_ramp_eval_transmit(ccl_private const ShaderClosure *sc,
-                                                    const float3 I,
-                                                    const float3 omega_in,
-                                                    ccl_private float *pdf)
-{
-  return zero_spectrum();
+  if (cos_pi >= 0.0f) {
+    *pdf = cos_pi * M_1_PI_F;
+    return rgb_to_spectrum(bsdf_diffuse_ramp_get_color(bsdf->colors, cos_pi) * M_1_PI_F);
+  }
+  else {
+    *pdf = 0.0f;
+    return zero_spectrum();
+  }
 }
 
 ccl_device int bsdf_diffuse_ramp_sample(ccl_private const ShaderClosure *sc,