From b2bc2077e5624b20d90565ee2f9564ce74f39c4d Mon Sep 17 00:00:00 2001
From: Garux <garux@mail.ru>
Date: Tue, 5 Jan 2021 01:34:55 +0300
Subject: [PATCH] prevent division by zero, which spreads darkness during
 bounces source of the problem is located somewhere else

---
 tools/quake3/q3map2/light_ydnar.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/quake3/q3map2/light_ydnar.c b/tools/quake3/q3map2/light_ydnar.c
index 1ded2a24..a9914f74 100644
--- a/tools/quake3/q3map2/light_ydnar.c
+++ b/tools/quake3/q3map2/light_ydnar.c
@@ -792,6 +792,12 @@ static bool MapTriangle( rawLightmap_t *lm, surfaceInfo_t *info, bspDrawVert_t *
 		return false;
 	}
 
+	/* this must not happen in the first place, but it does and spreads result of division by zero in MapSingleLuxel all over the map during -bounce */
+	if( lm->vecs != NULL && plane[lm->axisNum] == 0 ){
+		Sys_Warning( "plane[lm->axisNum] == 0\n" );
+		return false;
+	}
+
 	/* check to see if we need to calculate texture->world tangent vectors */
 	if ( info->si->normalImage != NULL && CalcTangentVectors( 3, dv, stvStatic, ttvStatic ) ) {
 		stv = stvStatic;