From 066d5c63e2599039bf69a2e1d4aa634af975f700 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Tue, 26 Apr 2016 21:55:17 +0200
Subject: [PATCH] - better be safe and not call GL_CLIP_DISTANCE functions on
 old hardware.

---
 src/gl/renderer/gl_renderstate.h | 15 ++++++++++++++-
 src/gl/scene/gl_decal.cpp        |  4 ----
 src/gl/scene/gl_drawinfo.cpp     | 14 ++++++++++----
 src/gl/scene/gl_sprite.cpp       |  4 ----
 src/gl/scene/gl_walls_draw.cpp   |  4 ----
 5 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/src/gl/renderer/gl_renderstate.h b/src/gl/renderer/gl_renderstate.h
index 04142a582..e61ab004d 100644
--- a/src/gl/renderer/gl_renderstate.h
+++ b/src/gl/renderer/gl_renderstate.h
@@ -233,7 +233,20 @@ public:
 
 	void EnableSplit(bool on)
 	{
-		mSplitEnabled = on;
+		if (gl.glslversion >= 1.3f)
+		{
+			mSplitEnabled = on;
+			if (on)
+			{
+				glEnable(GL_CLIP_DISTANCE3);
+				glEnable(GL_CLIP_DISTANCE4);
+			}
+			else
+			{
+				glDisable(GL_CLIP_DISTANCE3);
+				glDisable(GL_CLIP_DISTANCE4);
+			}
+		}
 	}
 
 	void SetLightIndex(int n)
diff --git a/src/gl/scene/gl_decal.cpp b/src/gl/scene/gl_decal.cpp
index 42d2eccbd..1a10b3f4d 100644
--- a/src/gl/scene/gl_decal.cpp
+++ b/src/gl/scene/gl_decal.cpp
@@ -388,8 +388,6 @@ void GLWall::DoDrawDecals()
 		if (lightlist != NULL)
 		{
 			gl_RenderState.EnableSplit(true);
-			glEnable(GL_CLIP_DISTANCE3);
-			glEnable(GL_CLIP_DISTANCE4);
 		}
 		else
 		{
@@ -405,8 +403,6 @@ void GLWall::DoDrawDecals()
 
 		if (lightlist != NULL)
 		{
-			glDisable(GL_CLIP_DISTANCE3);
-			glDisable(GL_CLIP_DISTANCE4);
 			gl_RenderState.EnableSplit(false);
 		}
 
diff --git a/src/gl/scene/gl_drawinfo.cpp b/src/gl/scene/gl_drawinfo.cpp
index 8bfa3df4e..386dc6a4a 100644
--- a/src/gl/scene/gl_drawinfo.cpp
+++ b/src/gl/scene/gl_drawinfo.cpp
@@ -806,11 +806,17 @@ void GLDrawList::DrawSorted()
 		sorted=DoSort(SortNodes[SortNodeStart]);
 	}
 	gl_RenderState.ClearClipSplit();
-	glEnable(GL_CLIP_DISTANCE1);
-	glEnable(GL_CLIP_DISTANCE2);
+	if (gl.glslversion >= 1.3f)
+	{
+		glEnable(GL_CLIP_DISTANCE1);
+		glEnable(GL_CLIP_DISTANCE2);
+	}
 	DoDrawSorted(sorted);
-	glDisable(GL_CLIP_DISTANCE1);
-	glDisable(GL_CLIP_DISTANCE2);
+	if (gl.glslversion >= 1.3f)
+	{
+		glDisable(GL_CLIP_DISTANCE1);
+		glDisable(GL_CLIP_DISTANCE2);
+	}
 	gl_RenderState.ClearClipSplit();
 }
 
diff --git a/src/gl/scene/gl_sprite.cpp b/src/gl/scene/gl_sprite.cpp
index 40aae9165..942a2e555 100644
--- a/src/gl/scene/gl_sprite.cpp
+++ b/src/gl/scene/gl_sprite.cpp
@@ -226,8 +226,6 @@ void GLSprite::Draw(int pass)
 	{
 		clipping = true;
 		gl_RenderState.EnableSplit(true);
-		glEnable(GL_CLIP_DISTANCE3);
-		glEnable(GL_CLIP_DISTANCE4);
 	}
 
 	secplane_t bottomp = { { 0, 0, -1. }, bottomclip };
@@ -333,8 +331,6 @@ void GLSprite::Draw(int pass)
 
 	if (clipping)
 	{
-		glDisable(GL_CLIP_DISTANCE3);
-		glDisable(GL_CLIP_DISTANCE4);
 		gl_RenderState.EnableSplit(false);
 	}
 
diff --git a/src/gl/scene/gl_walls_draw.cpp b/src/gl/scene/gl_walls_draw.cpp
index 5d5a1a7c3..8fe9d948e 100644
--- a/src/gl/scene/gl_walls_draw.cpp
+++ b/src/gl/scene/gl_walls_draw.cpp
@@ -339,8 +339,6 @@ void GLWall::RenderTextured(int rflags)
 	else
 	{
 		gl_RenderState.EnableSplit(true);
-		glEnable(GL_CLIP_DISTANCE3);
-		glEnable(GL_CLIP_DISTANCE4);
 
 		for (unsigned i = 0; i < lightlist->Size(); i++)
 		{
@@ -363,8 +361,6 @@ void GLWall::RenderTextured(int rflags)
 			if (low1 <= zbottom[0] && low2 <= zbottom[1]) break;
 		}
 
-		glDisable(GL_CLIP_DISTANCE3);
-		glDisable(GL_CLIP_DISTANCE4);
 		gl_RenderState.EnableSplit(false);
 	}
 	gl_RenderState.SetTextureMode(tmode);