From 4d27357dfe703c56ed4d6346690eeb64c2c703b7 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 1 Sep 2016 16:41:15 +0300
Subject: [PATCH] Access clipping through the extension mechanism

It's not supported on OpenGL ES.
---
 extensions/msp_clipping.glext |  1 +
 gl.fixes.xml                  | 15 +++++++++++++++
 source/clipping.cpp           |  4 +++-
 source/clipplane.cpp          |  4 +++-
 source/clipunit.cpp           |  2 ++
 5 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 extensions/msp_clipping.glext

diff --git a/extensions/msp_clipping.glext b/extensions/msp_clipping.glext
new file mode 100644
index 00000000..b94288cf
--- /dev/null
+++ b/extensions/msp_clipping.glext
@@ -0,0 +1 @@
+extension MSP_clipping
diff --git a/gl.fixes.xml b/gl.fixes.xml
index f3e2e60e..8edc3731 100644
--- a/gl.fixes.xml
+++ b/gl.fixes.xml
@@ -153,6 +153,8 @@
                 <command name="glNormalPointer" />
                 <command name="glColorPointer" />
                 <command name="glTexCoordPointer" />
+
+                <command name="glClipPlane" />
             </require>
         </extension>
 
@@ -164,6 +166,19 @@
             </require>
         </extension>
 
+        <!-- OpenGL ES does not have harwdare clipping. -->
+        <extension name="GL_MSP_clipping" supported="gl">
+            <require>
+                <enum name="GL_MAX_CLIP_PLANES" />
+                <enum name="GL_CLIP_PLANE0" />
+                <enum name="GL_CLIP_PLANE1" />
+                <enum name="GL_CLIP_PLANE2" />
+                <enum name="GL_CLIP_PLANE3" />
+                <enum name="GL_CLIP_PLANE4" />
+                <enum name="GL_CLIP_PLANE5" />
+            </require>
+        </extension>
+
         <!-- Stereo rendering is not supported on OpenGL ES, but I'm not
         certain enough of its uselessness to remove the constants outright. -->
         <extension name="GL_MSP_stereo_rendering" supported="gl">
diff --git a/source/clipping.cpp b/source/clipping.cpp
index 430a7b6f..6508ecf7 100644
--- a/source/clipping.cpp
+++ b/source/clipping.cpp
@@ -1,3 +1,4 @@
+#include <msp/gl/extensions/msp_clipping.h>
 #include <msp/gl/extensions/msp_legacy_features.h>
 #include "clipping.h"
 #include "clipplane.h"
@@ -55,8 +56,9 @@ void Clipping::update_shader_data(ProgramData &shdata, const Matrix &view_matrix
 
 void Clipping::bind(bool legacy) const
 {
+	static Require _req(MSP_clipping);
 	if(legacy)
-		static Require _req(MSP_legacy_features);
+		static Require _req2(MSP_legacy_features);
 	
 	if(legacy!=bound_with_legacy)
 		unbind();
diff --git a/source/clipplane.cpp b/source/clipplane.cpp
index e0b425a4..21df0d17 100644
--- a/source/clipplane.cpp
+++ b/source/clipplane.cpp
@@ -1,3 +1,4 @@
+#include <msp/gl/extensions/msp_clipping.h>
 #include <msp/gl/extensions/msp_legacy_features.h>
 #include <msp/strings/format.h>
 #include "clipplane.h"
@@ -50,7 +51,8 @@ void ClipPlane::update_shader_data(ProgramData &shdata, const Matrix &view_inver
 
 void ClipPlane::bind_to(unsigned i) const
 {
-	Require _req(MSP_legacy_features);
+	Require _req(MSP_clipping);
+	Require _req2(MSP_legacy_features);
 
 	ClipUnit &unit = ClipUnit::get_unit(i);
 	if(unit.set_plane(this))
diff --git a/source/clipunit.cpp b/source/clipunit.cpp
index 83080bd7..2db721cf 100644
--- a/source/clipunit.cpp
+++ b/source/clipunit.cpp
@@ -1,3 +1,4 @@
+#include <msp/gl/extensions/msp_clipping.h>
 #include <stdexcept>
 #include "clipunit.h"
 #include "gl.h"
@@ -24,6 +25,7 @@ bool ClipUnit::set_plane(const ClipPlane *p)
 
 unsigned ClipUnit::get_n_units()
 {
+	static Require _req(MSP_clipping);
 	static int count = get_i(GL_MAX_CLIP_PLANES);
 	return count;
 }
-- 
2.43.0