From ab4398e4406c5b68332e45ce906830d1cc4d674e Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 15 May 2007 11:25:14 +0000
Subject: [PATCH] From Farshid Lashkari, "I made a modification to the
 setClientActiveTextureUnit and setActiveTextureUnit methods of osg::State so
 they return false if the texture unit is outside the range of allowable units
 for the driver. Currently, the functions would return true even if the units
 are invalid. This would cause the osg::State to become out of sync with the
 actual driver state, which can cause some bugs in certain cases.

The change I made would verify that the unit passed to
setClientActiveTextureUnit is below GL_MAX_TEXTURE_COORDS, and the
unit passed to setActiveTextureUnit is below
max(GL_MAX_TEXTURE_COORDS,GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS). I
modeled this behavior from the OpenGL docs for these commands which
can be found here:

http://www.opengl.org/sdk/docs/man/xhtml/glClientActiveTexture.xml
http://www.opengl.org/sdk/docs/man/xhtml/glActiveTexture.xml
"
---
 include/osg/State |  2 ++
 src/osg/State.cpp | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/osg/State b/include/osg/State
index d1da97c95..d25ff91f5 100644
--- a/include/osg/State
+++ b/include/osg/State
@@ -1293,6 +1293,8 @@ class OSG_EXPORT State : public Referenced
 
 
         bool                        _extensionProcsInitialized;
+        GLint                       _glMaxTextureCoords;
+        GLint                       _glMaxTextureUnits;
         ActiveTextureProc           _glClientActiveTexture;
         ActiveTextureProc           _glActiveTexture;
         FogCoordPointerProc         _glFogCoordPointer;
diff --git a/src/osg/State.cpp b/src/osg/State.cpp
index 62e441c33..ba19b1413 100644
--- a/src/osg/State.cpp
+++ b/src/osg/State.cpp
@@ -15,6 +15,13 @@
 #include <osg/GLU>
 #include <osg/GLExtensions>
 
+#ifndef GL_MAX_TEXTURE_COORDS
+#define GL_MAX_TEXTURE_COORDS 0x8871
+#endif
+
+#ifndef GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS
+#define GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS 0x8B4D
+#endif
 
 using namespace std;
 using namespace osg;
@@ -734,6 +741,13 @@ void State::initializeExtensionProcs()
     _glDisableVertexAttribArray =  (DisableVertexAttribProc) osg::getGLExtensionFuncPtr("glDisableVertexAttribArray","glDisableVertexAttribArrayARB");
     _glBindBuffer = (BindBufferProc) osg::getGLExtensionFuncPtr("glBindBuffer","glBindBufferARB");
 
+    _glMaxTextureCoords = 1;
+    glGetIntegerv(GL_MAX_TEXTURE_COORDS,&_glMaxTextureCoords);
+
+    _glMaxTextureUnits = 1;
+    glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS,&_glMaxTextureUnits);
+    _glMaxTextureUnits = maximum(_glMaxTextureCoords,_glMaxTextureUnits);
+
     _extensionProcsInitialized = true;
 }
 
@@ -741,7 +755,7 @@ bool State::setClientActiveTextureUnit( unsigned int unit )
 {
     if (unit!=_currentClientActiveTextureUnit)
     {
-        if (_glClientActiveTexture)
+        if (_glClientActiveTexture && unit < (unsigned int)_glMaxTextureCoords)
         {
             _glClientActiveTexture(GL_TEXTURE0+unit);
             _currentClientActiveTextureUnit = unit;
@@ -761,7 +775,7 @@ bool State::setActiveTextureUnit( unsigned int unit )
 {
     if (unit!=_currentActiveTextureUnit)
     {
-        if (_glActiveTexture)
+        if (_glActiveTexture && unit < (unsigned int)_glMaxTextureUnits)
         {
             _glActiveTexture(GL_TEXTURE0+unit);
             _currentActiveTextureUnit = unit;