From 3b192f51197435010a1d456130fc275c9be244e2 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 8 Jan 2009 11:19:21 +0000
Subject: [PATCH] Added checked from the ARG version of glDraw*Instanced().

---
 include/osg/GLExtensions | 32 ++++++++++++++++++++++++++++++++
 src/osg/State.cpp        |  4 ++--
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/include/osg/GLExtensions b/include/osg/GLExtensions
index 350a4a87e..fb3e4fd37 100644
--- a/include/osg/GLExtensions
+++ b/include/osg/GLExtensions
@@ -78,6 +78,22 @@ inline void* getGLExtensionFuncPtr(const char *funcName,const char *fallbackFunc
     return getGLExtensionFuncPtr(fallbackFuncName);
 }
 
+/** Return the address of the specified OpenGL function. If not found then
+  * check a second function name, if this fails then return NULL as function is
+  * not supported by OpenGL library. This is used for checking something
+  * like glActiveTexture (which is in OGL1.3) or glActiveTextureARB.
+*/
+inline void* getGLExtensionFuncPtr(const char *funcName1, const char *funcName2, const char *funcName3)
+{
+    void* ptr = getGLExtensionFuncPtr(funcName1);
+    if (ptr) return ptr;
+
+    ptr = getGLExtensionFuncPtr(funcName2);
+    if (ptr) return ptr;
+
+    return getGLExtensionFuncPtr(funcName3);
+}
+
 template<typename T, typename R>
 T convertPointerType(R src)
 {
@@ -118,6 +134,22 @@ bool setGLExtensionFuncPtr(T& t, const char* str1, const char* str2)
     }
 }
 
+template<typename T>
+bool setGLExtensionFuncPtr(T& t, const char* str1, const char* str2, const char* str3)
+{
+    void* data = osg::getGLExtensionFuncPtr(str1,str2,str3);
+    if (data)
+    {
+        memcpy(&t, &data, sizeof(T));
+        return true;        
+    }
+    else
+    {
+        t = 0;
+        return false;        
+    }
+}
+
 
 /** Return true if OpenGL "extension" is supported.
   * Note: Must only be called within a valid OpenGL context,
diff --git a/src/osg/State.cpp b/src/osg/State.cpp
index cf6d0a826..99f4434cd 100644
--- a/src/osg/State.cpp
+++ b/src/osg/State.cpp
@@ -756,8 +756,8 @@ void State::initializeExtensionProcs()
     setGLExtensionFuncPtr(_glDisableVertexAttribArray, "glDisableVertexAttribArray","glDisableVertexAttribArrayARB");
     setGLExtensionFuncPtr(_glBindBuffer, "glBindBuffer","glBindBufferARB");
 
-    setGLExtensionFuncPtr(_glDrawArraysInstanced, "glDrawArraysInstanced","glDrawArraysInstancedEXT");
-    setGLExtensionFuncPtr(_glDrawElementsInstanced, "glDrawElementsInstanced","glDrawElementsInstancedEXT");
+    setGLExtensionFuncPtr(_glDrawArraysInstanced, "glDrawArraysInstanced","glDrawArraysInstancedARB","glDrawArraysInstancedEXT");
+    setGLExtensionFuncPtr(_glDrawElementsInstanced, "glDrawElementsInstanced","glDrawElementsInstancedARB","glDrawElementsInstancedEXT");
 
     if ( osg::getGLVersionNumber() >= 2.0 || osg::isGLExtensionSupported(_contextID,"GL_ARB_vertex_shader") )
     {