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VeryUseless

OpenGL OpenGLES - Texture Projection?

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VeryUseless    122
Hey guys, Not sure where to ask this, but I've searched high n low and I'm more stuck than a glue sniffer on Tuesday. Can someone give me some help working out how to go texture projection in OpenGL ES? It doesn't have the EYE_LINEAR stuff, which means it all has to be done manually, which is fine if you know how. :) I've googles for hours today and just keep finding the same examples using the OpenGL eye_linear stuff. In standard OpenGL, no worries, but ES is hampering me. Any help or links to examples or anything would be well n truly appreciated! Thanks!

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ZaiPpA    122
Do you mean 'projective texturing'? Where you have a 'projector' (lightsource) that projects an image (texture) onto the objects in your scene? I.e. where you instead of manually supplying a texture-coordinate for each vertex, you calculate them such that it looks like an image is projected onto the objects?

If so, i learned it from the "Cg Tutorial" chapter 9.3. This book is now avaliable online for free at: http://developer.nvidia.com/object/cg_tutorial_home.html

(i could have written a longer explanation here, but i'm not yet 100% sure we're talking about the same thing)


Note, i don't know anything about OpenGL ES, but it seems like you do have shaders. Also, i've never used glTexGen. If you have shaders, glTexGen is unnecessary, since you can calculate the texture coords however you want in your shaders yourself.

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swiftcoder    18432
Quote:
Original post by ZaiPpA
Note, i don't know anything about OpenGL ES, but it seems like you do have shaders. Also, i've never used glTexGen. If you have shaders, glTexGen is unnecessary, since you can calculate the texture coords however you want in your shaders yourself.
OpenGL ES 2.0 has shaders, ES 1.1 does not. Unfortunately, ES 2.0 devices are still relatively rare, while 1.1 devices (such as the iPhone) are quite common.

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VeryUseless    122
Thanks, but yeah, unfortunately no shader support under OpenGL ES 1.1.

That's exactly what I'm trying to do tho, project a texture like a slide projector, but I need to do the matrix maths all manually.

Any ideas?

Thanks again.

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