Cycles: include more transparency and emission in fast GI approximation

For indirect light rays, don't assume any hit is opaque, rather if it has
transparency or emission do the shading but don't do any further bounces.

Naturally this is slower when there are transparent surfaces, however
without this cutout opacity doesn't give sensible results.

Differential Revision: https://developer.blender.org/D10985

1 files changed, 14 insertions, 3 deletions

diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 5681510fc25..dd2390808ea 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -65,7 +65,6 @@ ccl_device_forceinline bool kernel_path_scene_intersect(KernelGlobals *kg,
   uint visibility = path_state_ray_visibility(kg, state);
 
   if (path_state_ao_bounce(kg, state)) {
-    visibility = PATH_RAY_SHADOW;
     ray->t = kernel_data.background.ao_distance;
   }
 
@@ -416,7 +415,13 @@ ccl_device void kernel_path_indirect(KernelGlobals *kg,
         break;
       }
       else if (path_state_ao_bounce(kg, state)) {
-        break;
+        if (intersection_get_shader_flags(kg, &isect) &
+            (SD_HAS_TRANSPARENT_SHADOW | SD_HAS_EMISSION)) {
+          state->flag |= PATH_RAY_TERMINATE_AFTER_TRANSPARENT;
+        }
+        else {
+          break;
+        }
       }
 
       /* Setup shader data. */
@@ -554,7 +559,13 @@ ccl_device_forceinline void kernel_path_integrate(KernelGlobals *kg,
         break;
       }
       else if (path_state_ao_bounce(kg, state)) {
-        break;
+        if (intersection_get_shader_flags(kg, &isect) &
+            (SD_HAS_TRANSPARENT_SHADOW | SD_HAS_EMISSION)) {
+          state->flag |= PATH_RAY_TERMINATE_AFTER_TRANSPARENT;
+        }
+        else {
+          break;
+        }
       }
 
       /* Setup shader data. */