From 1ef3f6df6d85627190e311b4b09f56a4983ec797 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 26 Oct 2016 22:13:38 +0300
Subject: [PATCH] Use the core version of primitive restart if possible

---
 extensions/msp_primitive_restart.glext |  1 +
 gl.fixes.xml                           | 10 +++++
 source/batch.cpp                       | 52 +++++++++++++++++++-------
 source/batch.h                         |  2 +
 4 files changed, 51 insertions(+), 14 deletions(-)
 create mode 100644 extensions/msp_primitive_restart.glext

diff --git a/extensions/msp_primitive_restart.glext b/extensions/msp_primitive_restart.glext
new file mode 100644
index 00000000..ea4a0710
--- /dev/null
+++ b/extensions/msp_primitive_restart.glext
@@ -0,0 +1 @@
+extension MSP_primitive_restart
diff --git a/gl.fixes.xml b/gl.fixes.xml
index 954785a6..bb149bd1 100644
--- a/gl.fixes.xml
+++ b/gl.fixes.xml
@@ -212,5 +212,15 @@
                 <enum name="GL_TEXTURE_1D" />
             </require>
         </extension>
+
+        <!-- The core version of primitive restart has different semantics
+        from the NV extension but is not available as a backport extension. -->
+        <extension name="GL_MSP_primitive_restart" supported="gl">
+            <require>
+                <enum name="GL_PRIMITIVE_RESTART" />
+                <enum name="GL_PRIMITIVE_RESTART_INDEX" />
+                <command name="glPrimitiveRestartIndex" />
+            </require>
+        </extension>
     </extensions>
 </registry>
diff --git a/source/batch.cpp b/source/batch.cpp
index 859a6ad5..3d7dfc72 100644
--- a/source/batch.cpp
+++ b/source/batch.cpp
@@ -1,5 +1,6 @@
 #include <msp/gl/extensions/ext_draw_range_elements.h>
 #include <msp/gl/extensions/msp_legacy_features.h>
+#include <msp/gl/extensions/msp_primitive_restart.h>
 #include <msp/gl/extensions/nv_primitive_restart.h>
 #include "batch.h"
 #include "bindable.h"
@@ -62,7 +63,7 @@ Batch::Batch(PrimitiveType t):
 {
 	/* Make sure we have glEnable/DisableClientState to go with
 	NV_primitive_restart */
-	if(NV_primitive_restart)
+	if(!MSP_primitive_restart && NV_primitive_restart)
 		(bool)MSP_legacy_features;
 }
 
@@ -125,7 +126,7 @@ bool Batch::can_append(PrimitiveType other_type)
 	if(other_type!=prim_type)
 		return false;
 	else if(prim_type==LINE_STRIP || prim_type==LINE_LOOP || prim_type==TRIANGLE_FAN)
-		return NV_primitive_restart;
+		return MSP_primitive_restart || NV_primitive_restart;
 	else
 		return true;
 }
@@ -135,14 +136,17 @@ void Batch::append(const Batch &other)
 	if(other.prim_type!=prim_type)
 		throw invalid_argument("Batch::append");
 	if(prim_type==LINE_STRIP || prim_type==LINE_LOOP || prim_type==TRIANGLE_FAN)
-		static Require _req(NV_primitive_restart);
+	{
+		if(!MSP_primitive_restart)
+			static Require _req(NV_primitive_restart);
+	}
 
 	if(other.data.empty())
 		return;
 
 	if(prim_type==POINTS || prim_type==LINES || prim_type==TRIANGLES || prim_type==QUADS)
 		;
-	else if(NV_primitive_restart)
+	else if(MSP_primitive_restart || NV_primitive_restart)
 	{
 		restart = true;
 		if(data_type==UNSIGNED_SHORT)
@@ -230,18 +234,10 @@ void Batch::draw() const
 			index = 0xFF;
 
 		if(index!=restart_index)
-		{
-			if(!restart_index)
-				glEnableClientState(GL_PRIMITIVE_RESTART_NV);
-			glPrimitiveRestartIndexNV(index);
-			restart_index = index;
-		}
+			set_restart_index(index);
 	}
 	else if(restart_index && restart_index<=max_index)
-	{
-		glDisableClientState(GL_PRIMITIVE_RESTART_NV);
-		restart_index = 0;
-	}
+		set_restart_index(0);
 
 	Buffer *ibuf = get_buffer();
 	const void *data_ptr;
@@ -262,6 +258,34 @@ void Batch::draw() const
 		glDrawElements(prim_type, size(), data_type, data_ptr);
 }
 
+void Batch::set_restart_index(unsigned index)
+{
+	if(MSP_primitive_restart)
+	{
+		if(index>0)
+		{
+			if(!restart_index)
+				glEnable(GL_PRIMITIVE_RESTART);
+			glPrimitiveRestartIndex(index);
+		}
+		else
+			glDisable(GL_PRIMITIVE_RESTART);
+	}
+	else
+	{
+		if(index>0)
+		{
+			if(!restart_index)
+				glEnableClientState(GL_PRIMITIVE_RESTART_NV);
+			glPrimitiveRestartIndexNV(index);
+		}
+		else
+			glDisableClientState(GL_PRIMITIVE_RESTART_NV);
+	}
+
+	restart_index = index;
+}
+
 
 Batch::Loader::Loader(Batch &b):
 	DataFile::ObjectLoader<Batch>(b)
diff --git a/source/batch.h b/source/batch.h
index 2f83207e..0d05d6d4 100644
--- a/source/batch.h
+++ b/source/batch.h
@@ -65,6 +65,8 @@ public:
 	unsigned get_index(unsigned) const;
 
 	void draw() const;
+private:
+	static void set_restart_index(unsigned);
 };
 
 } // namespace GL
-- 
2.45.2