From 5a6a9c30d1aef72b39ab8b6866eb4a237b187314 Mon Sep 17 00:00:00 2001
From: stevenaaus <stevenaaus@af15c1b1-3010-417e-b628-4374ebc0bcbd>
Date: Wed, 24 Aug 2011 07:47:29 +0000
Subject: [PATCH] z-fighting (flickering gl texture clash most notable in e1m1)
 bug fix, from Sander.

git-svn-id: http://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@480 af15c1b1-3010-417e-b628-4374ebc0bcbd
---
 Quake/gl_rmain.c |  2 ++
 Quake/gl_rmisc.c |  4 ++++
 Quake/quakedef.h |  2 ++
 Quake/r_brush.c  | 14 ++++++++++++++
 Quake/world.c    |  3 ---
 5 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/Quake/gl_rmain.c b/Quake/gl_rmain.c
index 1cc642a2..bb4baf98 100644
--- a/Quake/gl_rmain.c
+++ b/Quake/gl_rmain.c
@@ -103,6 +103,8 @@ cvar_t	r_nolerp_list = {"r_nolerp_list", "progs/flame.mdl,progs/flame2.mdl,progs
 extern cvar_t	r_vfog;
 //johnfitz
 
+cvar_t	gl_zfix = {"gl_zfix", "1", true}; // QuakeSpasm z-fighting fix
+
 qboolean r_drawflat_cheatsafe, r_fullbright_cheatsafe, r_lightmap_cheatsafe, r_drawworld_cheatsafe; //johnfitz
 
 /*
diff --git a/Quake/gl_rmisc.c b/Quake/gl_rmisc.c
index 718aa97c..521656fe 100644
--- a/Quake/gl_rmisc.c
+++ b/Quake/gl_rmisc.c
@@ -45,6 +45,8 @@ extern cvar_t r_lerpmove;
 extern cvar_t r_nolerp_list;
 //johnfitz
 
+extern cvar_t gl_zfix; // QuakeSpasm z-fighting fix
+
 extern float load_subdivide_size; //johnfitz -- remember what subdivide_size value was when this map was loaded
 
 extern cvar_t gl_subdivide_size; //johnfitz -- moved here from gl_model.c
@@ -240,6 +242,8 @@ void R_Init (void)
 	Cvar_RegisterVariable (&r_nolerp_list, R_NoLerpList_f);
 	//johnfitz
 
+	Cvar_RegisterVariable (&gl_zfix, NULL); // QuakeSpasm z-fighting fix
+
 	Cvar_RegisterVariable (&gl_subdivide_size, NULL); //johnfitz -- moved here from gl_model.c
 
 	R_InitParticles ();
diff --git a/Quake/quakedef.h b/Quake/quakedef.h
index 9659eaae..c121ae75 100644
--- a/Quake/quakedef.h
+++ b/Quake/quakedef.h
@@ -73,6 +73,8 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #define	ON_EPSILON		0.1			// point on plane side epsilon
 
+#define	DIST_EPSILON		(0.03125)		// 1/32 epsilon to keep floating point happy (moved from world.c)
+
 #define	MAX_MSGLEN		32000	// max length of a reliable message //johnfitz -- was 8000
 #define	MAX_DATAGRAM		32000	// max length of unreliable message //johnfitz -- was 1024
 
diff --git a/Quake/r_brush.c b/Quake/r_brush.c
index 8c2e135a..f9ee5c1e 100644
--- a/Quake/r_brush.c
+++ b/Quake/r_brush.c
@@ -25,6 +25,8 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 extern cvar_t gl_fullbrights, r_drawflat, gl_overbright, r_oldwater; //johnfitz
 
+extern cvar_t gl_zfix; // QuakeSpasm z-fighting fix
+
 int		gl_lightmap_format;
 int		lightmap_bytes;
 
@@ -543,7 +545,19 @@ void R_DrawBrushModel (entity_t *e)
 
     glPushMatrix ();
 	e->angles[0] = -e->angles[0];	// stupid quake bug
+	if (gl_zfix.value)
+	{
+		e->origin[0] -= DIST_EPSILON;
+		e->origin[1] -= DIST_EPSILON;
+		e->origin[2] -= DIST_EPSILON;
+	}
 	R_RotateForEntity (e->origin, e->angles);
+	if (gl_zfix.value)
+	{
+		e->origin[0] += DIST_EPSILON;
+		e->origin[1] += DIST_EPSILON;
+		e->origin[2] += DIST_EPSILON;
+	}
 	e->angles[0] = -e->angles[0];	// stupid quake bug
 
 	//
diff --git a/Quake/world.c b/Quake/world.c
index c6db6b5a..64cfa8f8 100644
--- a/Quake/world.c
+++ b/Quake/world.c
@@ -556,9 +556,6 @@ LINE TESTING IN HULLS
 ===============================================================================
 */
 
-// 1/32 epsilon to keep floating point happy
-#define	DIST_EPSILON	(0.03125)
-
 /*
 ==================
 SV_RecursiveHullCheck