openGL textures that are not 2^x in dimention

Question

I'm trying to display a picture in an openGL environment. The picture's origninal dimensions are 3648x2432, and I want to display it with a 256x384 image. The problem is, 384 is not a power of 2, and when I try to display it, it looks stretched. How can I fix that?

score 3 · Accepted Answer · answered Dec 12 '08 at 16:54

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There's three ways of doing this that I know of -

The one Albert suggested (resize it until it fits).
Subdivide the texture into 2**n-sized rectangles, and piece them together in some way.
See if you can use GL_ARB_texture_non_power_of_two. It's probably best to avoid it though, since it looks like it's an Xorg-specific extension.

answered Dec 12 '08 at 16:54

Option 2 is great - prevents loss of fidelity – Frank Krueger Dec 23 '08 at 20:10

score 2 · Answer 2 · answered Dec 12 '08 at 16:46

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You can resize your texture so it is a power of two (skew your texture so that when it is mapped onto the object it looks correct).

answered Dec 12 '08 at 16:46

Albert

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I am under the impression that textures are always a power of two because the hardware would use the same amount of resources anyways. But I could be incorrect. – Albert Dec 12 '08 at 16:47

score 0 · Answer 3 · answered Dec 12 '08 at 17:01

ARB_texture_rectangle is probably what you're looking for. It lets you bind to GL_TEXTURE_RECTANGLE_ARB instead of GL_TEXTURE_2D, and you can load an image with non power-of-2 dimensions. Be aware that your texture coordinates will range from [0..w]x[0..h] instead of [0..1]x[0..1].

score 0 · Answer 4 · answered Dec 23 '08 at 20:08

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If GL_EXT_texture_rectangle is true then use GL_TEXTURE_RECTANGLE_EXT for the first param in glEnable() and GLBindTexture() calls.

answered Dec 23 '08 at 20:08

Mark

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openGL textures that are not 2^x in dimention

4 Answers4