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> I'm creating a painting application backed by JOGL.  I have a tool that
> allows the user to click and drag to draw brush strokes on the screen.  
>
> At the moment, the brushstroke drawing code is all being done with
> BufferedImages.  At the moment the user starts dragging, a BufferedImage is
> allocated to capture the entire stroke.  Another BufferedImage is also
> created which is filled with the image of the head of the brush.  As the
> user drags the mouse, the trajectory is calculated and used to draw many
> copies of the brush tip image into the stroke collector buffer.  When the
> user is done, the stroke collector image is then drawn into the scene as a
> whole.
>
> The above process is quite slow, and since I am already using JOGL to render
> to the screen, it would be nice if I could do this offscreen task using JOGL
> too.  The trouble is, I need to compute my stroke buffer as I receive mouse
> input, so I can't wait until the GLEventListener sends me the
> GLAutoDrawable.  

> One option is to create a second rendering context -
> however, I would like to be able to render the partially completed stroke
> buffer over top of my image to give the user some visual feedback.  If I'm
> using two separate GL contexts, I'd have to read the stroke buffer image out
> of one into the CPU and then write it back into the other.  Being able to do
> everything in the same GL context would save me that very expensive step.
>
> I'd plan to use framebuffer render-to-texture techniques to do the actual
> compositing.  How would I set up JOGL so that a Swing thread could jump in
> and read and write framebuffer textures on the fly?
>