[Bf-blender-cvs] [c3237cdc139] blender-v2.79a-release: Fix T53012: Shadow catcher creates artifacts on contact area

[Sergey Sharybin]

Commit: c3237cdc13925db9e3e6865efb9570c7a1f214ce
Author: Sergey Sharybin
Date:   Mon Jan 22 12:38:27 2018 +0100
Branches: blender-v2.79a-release
https://developer.blender.org/rBc3237cdc13925db9e3e6865efb9570c7a1f214ce

Fix T53012: Shadow catcher creates artifacts on contact area

The issue was caused by light sample being evaluated to nan at some point.
This is root of the cause which is to be fixed, but is very hard to trace down
especially via ssh (the issue only happens on AVX2 release build). Will give it
a closer look when back to my AVX2 machine.

For until then this is a good check to have anyway, it corresponds to what's
happening in regular radiance sum.

===================================================================

M	intern/cycles/kernel/kernel_accumulate.h

===================================================================

diff --git a/intern/cycles/kernel/kernel_accumulate.h b/intern/cycles/kernel/kernel_accumulate.h
index 9ed16aceb55..a290b13f9da 100644
--- a/intern/cycles/kernel/kernel_accumulate.h
+++ b/intern/cycles/kernel/kernel_accumulate.h
@@ -668,6 +668,10 @@ ccl_device_inline float path_radiance_sum_shadow(const PathRadiance *L)
 {
 	float path_total = average(L->path_total);
 	float path_total_shaded = average(L->path_total_shaded);
+	if(UNLIKELY(!isfinite_safe(path_total))) {
+		kernel_assert(!"Non-finite total radiance along the path");
+		return 0.0f;
+	}
 	if(path_total != 0.0f) {
 		return path_total_shaded / path_total;
 	}