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Reflections

Started by AndyEsser Jun 1, 2006 at 5:11 PM 2 replies 550+ views

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AndyEsser

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AndyEsser

Jun 1, 2006 at 5:11 PM

For reflections on consoles and glass etc I've found articles that suggest the use of glReadPixels() but when i've tried to implement this it all goes wrong. I'm doing this: glReadPixels 0, 0, Screen.Width, Screen.height, rpRGB, pxlByte, reflection and it's causing VB to crash to desktop or throw up a memory error. I've tried it with pxlFloat as well and still nothing. Can anyone suggest what's going on? Thanks Andy

Solias

Jun 1, 2006 at 7:02 PM

I've never used opengl with vb, but is reflection big enough to hold the result of the read pixels call? It's possible your vb ogl binding may check the params for you, but the underlying ogl implementation won't. That sounds like the kind of thing that would result in a memory error.

At a more fundamental level I think this may be the wrong approach. Are you planning to load this pixel data into a texture to display the reflection? Read pixels is going to be slow, and if you are just sending the data back across the bus it is not needed. Take a look at glCopyTexImage2D and glCopyTexSubImage2D as alternatives for getting data from the screen to a texture. You may also want to look at the FBO extension eventually, but probably start with the copy functions.

AndyEsser

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AndyEsser

Jun 2, 2006 at 6:00 AM

Thanks for your help. I'll check out those other functions.

thanks

cwhite

Jun 2, 2006 at 10:09 AM

You might as well just bite the bullet and learn how to use framebuffer objects. They're the way of the future for rendering to a texture, and their only downfall is a slight lack of good documentation. But it's worth the effort. There's really no point in learning a deprecated technology.

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