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

@@ -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;
 

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)

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(),