It's a minimal change, it just calls an already existing protected method. It was trivial to subclass the handler to do it in our code, but pushing the change into OSG makes sense as it's generally useful to have it in the handler itself.
I also noticed that the handle() method was overridden from osgGA::GUIEventHandler but wasn't marked virtual. It wasn't intended that subclasses not be able to override it in turn, so I've added the keyword.""
returns true if (the extension string is supported or GL version is greater than or equal to a specified version) and
non extension disable is used. This makes it possible to disable extensions that are now
available as parts of the core OpenGL spec.
Updated Texture.cpp is use this method.
/** Convinience method that sets the update callback of the node if it doesn't exist, or nest it into the existing one. */
void addUpdateCallback(NodeCallback* nc);
/** Convinience method that removes a given callback from a node, even if that callback is nested. There is no error return in case the given callback is not found. */
void removeUpdateCallback(NodeCallback* nc);
... and the same for Event and Cull callbacks methods."
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Descripton:
The patch does provide a new class PixelDataBufferObject which is capable of allocating memory on the GPU side (PBO memory) of arbitrary size. The memory can then further be used to be enabled into read mode (GL_PIXEL_UNPACK_BUFFER_ARB) or in write mode (GL_PIXEL_PACK_BUFFER_ARB). Enabling the buffer into write mode will force the driver to write data from bounded textures into that buffer (i.e. glGetTexImage). Using buffer in read mode give you the possibility to read data from the buffer into a texture with e.g. glTexSubImage or other instuctions. Hence no data is copied over the CPU (host memory), all the operations are done in the GPU memory.
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Compatibility:
The new class require the unbindBuffer method from the base class BufferObject to be virtual, which shouldn't break any functionality of already existing classes. Except of this the new class is fully orthogonal to existing one, hence can be safely added into already existing osg system.
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Testing:
The new class was tested in the current svn version of osgPPU. I am using the new class to copy data from textures into the PBO and hence provide them to CUDA kernels. Also reading the results back from CUDA is implemented using the provided patch. The given patch gives a possibility of easy interoperability between CUDA and osg (osgPPU ;) )
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I think in general it is a better way to derive the PixelBufferObject class from PixelDataBufferObject, since the second one is a generalization of the first one. However this could break the current functionality, hence I haven't implemented it in such a way. However I would push that on a stack of wished osg 3.x features, since this will reflect the OpenGL PBO functionality through the classes better.
"
