subtexture

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This extension allows a contiguous portion of an already-existing texture image to be redefined, without affecting the remaining portion of the image.

• Additionally, this extensions allows the definition of a null image with the texture definition, so that the image data can be added later.
  
  
• This is particularly useful when animating a portion of a texture image as in video textures where the overhead of continually creating and deleting textures would be prohibitively high.