From b68ba8c983513f237617608fb6715925a66a5dee Mon Sep 17 00:00:00 2001
From: Eric Wasylishen <ewasylishen@gmail.com>
Date: Wed, 5 Aug 2015 13:47:04 -0600
Subject: [PATCH] light: average the color to get the value to write to the
 .bsp lightmap.

This avoids issues with some engines that require the lit and internal lightmap to have the same intensity. (MarkV, some QW engines).
Previously, if you used low-value colors (e.g. "0.2 0 0"), the .bsp lightmap and .lit file could have vastly different brightness.
---
 light/ltface.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/light/ltface.c b/light/ltface.c
index 0a1be021..b4d6afe3 100644
--- a/light/ltface.c
+++ b/light/ltface.c
@@ -1262,7 +1262,6 @@ WriteLightmaps(bsp2_dface_t *face, const lightsurf_t *lightsurf,
 	    for (s = 0; s <= lightsurf->texsize[0]; s++) {
 
 		/* Take the average of any oversampling */
-		light = 0;
 		VectorCopy(vec3_origin, color);
 		VectorCopy(vec3_origin, direction);
 		for (i = 0; i < oversample; i++) {
@@ -1272,24 +1271,13 @@ WriteLightmaps(bsp2_dface_t *face, const lightsurf_t *lightsurf,
 
 			sample = lightmaps[mapnum].samples + (row * width) + col;
 			
-			light += sample->light;
 			VectorAdd(color, sample->color, color);
 			VectorAdd(direction, sample->direction, direction);
 		    }
 		}
-		light /= oversample * oversample;
 		VectorScale(color, 1.0 / oversample / oversample, color);
 
 		/* Scale and clamp any out-of-range samples */
-		light *= rangescale;
-		if (light > 0)
-		    light = pow( light / 255.0f, 1.0 / lightmapgamma ) * 255.0f;
-		if (light > 255)
-		    light = 255;
-		else if (light < 0)
-		    light = 0;
-		*out++ = light;
-
 		maxcolor = 0;
 		VectorScale(color, rangescale, color);
 		for (i = 0; i < 3; i++)
@@ -1303,6 +1291,16 @@ WriteLightmaps(bsp2_dface_t *face, const lightsurf_t *lightsurf,
 		*lit++ = color[0];
 		*lit++ = color[1];
 		*lit++ = color[2];
+		
+		/* Average the color to get the value to write to the
+		   .bsp lightmap. this avoids issues with some engines
+		   that require the lit and internal lightmap to have the same
+		   intensity. (MarkV, some QW engines)
+		 */
+		light = (color[0] + color[1] + color[2]) / 3.0;
+		if (light < 0) light = 0;
+		if (light > 255) light = 255;
+		*out++ = light;
 
 		if (lux)
 		{