multiple layers in OpenGL?
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I want to add rectangle selection to my application. I would like to draw a semi-transparent rectangle while mouse is moved but I do not want to render again all the scene objects. It's like to draw in one layer, letting intact the another layer.
Is there any way to make it? I have heard something like aux_buffers, but I don't know how to use it.
Could anybody help me, please???
Thanks in advance
Never have made something like that myself, but the following things come to my mind:
Render the scene to a texture, render the texture window/screen filled, and render the selection above it. Rendering to a texture could be done in several ways. The slowest is to do a glReadPixels and making a texture manually from it. Next, there are some render-to-texture extensions out there. The best way nowadays may be to use PBO (pixel buffer objects). However, you don't have to extract the scene as a background for every frame, so also the less speedy ways may be sufficient.
Render the scene to a texture, render the texture window/screen filled, and render the selection above it. Rendering to a texture could be done in several ways. The slowest is to do a glReadPixels and making a texture manually from it. Next, there are some render-to-texture extensions out there. The best way nowadays may be to use PBO (pixel buffer objects). However, you don't have to extract the scene as a background for every frame, so also the less speedy ways may be sufficient.
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