From 48b9b25805644b34539801991bc5b95c62be1a0a Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Mon, 20 Feb 2012 12:03:14 +0000
Subject: [PATCH] From Johannes Baeurele, "The osg::Image class now contains a
 'supportsTextureSubloading()' method that is used inside the Texture2D::apply
 method. For now it only checks for the etc1 format in which case it returns
 'false'. All other formats lead to a return value of 'true'.

Without the change the application does not work properly. First I get the notification that an OpenGL error occured. After some more of this error messages I see broken textures on the screen. With the changes attached to this message my application works as intended."

Note from Robert Osfield, changed the Image::supportsTextureSubloading() to be const and to be implemented in the .cpp rather than inline.
---
 include/osg/Image     |  7 +++++++
 src/osg/Image.cpp     | 11 +++++++++++
 src/osg/Texture2D.cpp |  2 +-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/osg/Image b/include/osg/Image
index 2c9cb3655..6e252cb2c 100644
--- a/include/osg/Image
+++ b/include/osg/Image
@@ -92,6 +92,10 @@
     #define GL_UNPACK_IMAGE_HEIGHT  0x806E
 #endif
 
+#ifndef GL_OES_compressed_ETC1_RGB8_texture
+    #define GL_ETC1_RGB8_OES        0x8D64   
+#endif
+
 namespace osg {
 
 // forward declare
@@ -396,6 +400,9 @@ class OSG_EXPORT Image : public BufferData
            return _data+getMipmapOffset(mipmapLevel);
         }
 
+        /** returns false for texture formats that do not support texture subloading */
+        bool supportsTextureSubloading() const;
+
         /** Return true if this image is translucent - i.e. it has alpha values that are less 1.0 (when normalized). */
         virtual bool isImageTranslucent() const;
 
diff --git a/src/osg/Image.cpp b/src/osg/Image.cpp
index 3994a016e..164b4fceb 100644
--- a/src/osg/Image.cpp
+++ b/src/osg/Image.cpp
@@ -1431,6 +1431,17 @@ void Image::ensureValidSizeForTexturing(GLint maxTextureSize)
     }
 }
 
+bool Image::supportsTextureSubloading() const
+{
+    switch(_internalTextureFormat)
+    {
+        case GL_ETC1_RGB8_OES:
+            return false;
+        default:
+            return true;
+    }
+}
+
 
 template <typename T>    
 bool _findLowerAlphaValueInRow(unsigned int num, T* data,T value, unsigned int delta)
diff --git a/src/osg/Texture2D.cpp b/src/osg/Texture2D.cpp
index 09ce2b556..0c9e1ac92 100644
--- a/src/osg/Texture2D.cpp
+++ b/src/osg/Texture2D.cpp
@@ -247,7 +247,7 @@ void Texture2D::apply(State& state) const
 
         applyTexParameters(GL_TEXTURE_2D,state);
 
-        if (textureObject->isAllocated())
+        if (textureObject->isAllocated() && image->supportsTextureSubloading())
         {
             //OSG_NOTICE<<"Reusing texture object"<<std::endl;
             applyTexImage2D_subload(state,GL_TEXTURE_2D,image.get(),