3 files changed, 14 insertions, 22 deletions

diff --git a/intern/cycles/kernel/light/background.h b/intern/cycles/kernel/light/background.h
index 2a97d43c9ce..951620ff1cb 100644
--- a/intern/cycles/kernel/light/background.h
+++ b/intern/cycles/kernel/light/background.h
@@ -9,8 +9,6 @@ CCL_NAMESPACE_BEGIN
 
 /* Background Light */
 
-#ifdef __BACKGROUND_MIS__
-
 ccl_device float3 background_map_sample(KernelGlobals kg,
                                         float randu,
                                         float randv,
@@ -435,6 +433,4 @@ ccl_device float background_light_pdf(KernelGlobals kg, float3 P, float3 directi
   return pdf * kernel_data.integrator.pdf_lights;
 }
 
-#endif
-
 CCL_NAMESPACE_END
diff --git a/intern/cycles/kernel/light/light.h b/intern/cycles/kernel/light/light.h
index b939489bb18..12a6f21b58d 100644
--- a/intern/cycles/kernel/light/light.h
+++ b/intern/cycles/kernel/light/light.h
@@ -86,7 +86,6 @@ ccl_device_inline bool light_sample(KernelGlobals kg,
     ls->pdf = invarea / (costheta * costheta * costheta);
     ls->eval_fac = ls->pdf;
   }
-#ifdef __BACKGROUND_MIS__
   else if (type == LIGHT_BACKGROUND) {
     /* infinite area light (e.g. light dome or env light) */
     float3 D = -background_light_sample(kg, P, randu, randv, &ls->pdf);
@@ -97,7 +96,6 @@ ccl_device_inline bool light_sample(KernelGlobals kg,
     ls->t = FLT_MAX;
     ls->eval_fac = 1.0f;
   }
-#endif
   else {
     ls->P = make_float3(klight->co[0], klight->co[1], klight->co[2]);
 
@@ -202,8 +200,12 @@ ccl_device_inline bool light_sample(KernelGlobals kg,
         inplane = ls->P - inplane;
       }
 
-      ls->u = dot(inplane, axisu) * (1.0f / dot(axisu, axisu)) + 0.5f;
-      ls->v = dot(inplane, axisv) * (1.0f / dot(axisv, axisv)) + 0.5f;
+      const float light_u = dot(inplane, axisu) * (1.0f / dot(axisu, axisu));
+      const float light_v = dot(inplane, axisv) * (1.0f / dot(axisv, axisv));
+
+      /* NOTE: Return barycentric coordinates in the same notation as Embree and OptiX. */
+      ls->u = light_v + 0.5f;
+      ls->v = -light_u - light_v;
 
       ls->Ng = Ng;
       ls->D = normalize_len(ls->P - P, &ls->t);
diff --git a/intern/cycles/kernel/light/sample.h b/intern/cycles/kernel/light/sample.h
index 4195675dd13..e0d4f221bef 100644
--- a/intern/cycles/kernel/light/sample.h
+++ b/intern/cycles/kernel/light/sample.h
@@ -4,7 +4,7 @@
 #pragma once
 
 #include "kernel/integrator/path_state.h"
-#include "kernel/integrator/shader_eval.h"
+#include "kernel/integrator/surface_shader.h"
 
 #include "kernel/light/light.h"
 
@@ -24,22 +24,19 @@ light_sample_shader_eval(KernelGlobals kg,
   /* setup shading at emitter */
   Spectrum eval = zero_spectrum();
 
-  if (shader_constant_emission_eval(kg, ls->shader, &eval)) {
+  if (surface_shader_constant_emission(kg, ls->shader, &eval)) {
     if ((ls->prim != PRIM_NONE) && dot(ls->Ng, ls->D) > 0.0f) {
       ls->Ng = -ls->Ng;
     }
   }
   else {
-    /* Setup shader data and call shader_eval_surface once, better
+    /* Setup shader data and call surface_shader_eval once, better
      * for GPU coherence and compile times. */
     PROFILING_INIT_FOR_SHADER(kg, PROFILING_SHADE_LIGHT_SETUP);
-#ifdef __BACKGROUND_MIS__
     if (ls->type == LIGHT_BACKGROUND) {
       shader_setup_from_background(kg, emission_sd, ls->P, ls->D, time);
     }
-    else
-#endif
-    {
+    else {
       shader_setup_from_sample(kg,
                                emission_sd,
                                ls->P,
@@ -63,18 +60,15 @@ light_sample_shader_eval(KernelGlobals kg,
 
     /* No proper path flag, we're evaluating this for all closures. that's
      * weak but we'd have to do multiple evaluations otherwise. */
-    shader_eval_surface<KERNEL_FEATURE_NODE_MASK_SURFACE_LIGHT>(
+    surface_shader_eval<KERNEL_FEATURE_NODE_MASK_SURFACE_LIGHT>(
         kg, state, emission_sd, NULL, PATH_RAY_EMISSION);
 
     /* Evaluate closures. */
-#ifdef __BACKGROUND_MIS__
     if (ls->type == LIGHT_BACKGROUND) {
-      eval = shader_background_eval(emission_sd);
+      eval = surface_shader_background(emission_sd);
     }
-    else
-#endif
-    {
-      eval = shader_emissive_eval(emission_sd);
+    else {
+      eval = surface_shader_emission(emission_sd);
     }
   }