From eaec325ab48279b3b85767c3bee840935b8484df Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Thu, 8 Sep 2016 21:39:37 -0600
Subject: [PATCH] light: bounce: area-weight the patches when averaging them to
 get the light to emit for a face

---
 light/light.cc | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/light/light.cc b/light/light.cc
index 89ababeb..0c5ebf57 100644
--- a/light/light.cc
+++ b/light/light.cc
@@ -871,14 +871,18 @@ MakeBounceLightsThread (void *arg)
         DiceWinding(winding, 64.0f, SaveWindingFn, &args);
         winding = nullptr; // DiceWinding frees winding
         
-        // average them
+        // average them, area weighted
         vec3_t sum = {0,0,0};
+        float totalarea = 0;
         if (patches.size()) {
             for (const auto &patch : patches) {
-                VectorAdd(sum, patch->directlight, sum);
+                const float patcharea = WindingArea(patch->w);
+                totalarea += patcharea;
+                
+                VectorMA(sum, patcharea, patch->directlight, sum);
 //              printf("  %f %f %f\n", patch->directlight[0], patch->directlight[1], patch->directlight[2]);
             }
-            VectorScale(sum, 1.0/patches.size(), sum);
+            VectorScale(sum, 1.0/totalarea, sum);
         }
     
         vec3_t texturecolor;