Thread: [OpenGL] Texture size

  1. #1
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    [OpenGL] Texture size

    I was wondering how you guys deal with the fact that the width and height of textures have to be a power of 2.

    For example: I have a window of 640x480. Should I stretch the background image for my window to 1024x512 or is there another way to have OpenGL accept my image?

    I'm using DevIL to import my images. Here it says under "How ILUT Handles Textures":

    Quote Originally Posted by Tutorial
    DevIL allows the use of arbitrarily-sized images, but OpenGL only works with images that have dimensions that are powers of 2, for optimization purposes. If an image has dimensions that are not powers of 2, DevIL will resize the image before sending it to OpenGL
    But this doesn't seem to happen. If I use an image with size 640x480, it doesn't show up when used as a texture. Any ideas?
    Last edited by Snip; 08-24-2005 at 01:22 PM.

  2. #2
    Deprecated Dae's Avatar
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    Oct 2004
    I might be wrong about the request, but according to NeHe you can use any size when for mitmapped textures:

    I had said in tutorial six there was a way around the 64,128,256,etc limit that OpenGL puts on texture width and height. gluBuild2DMipmaps is it. From what I've found, you can use any bitmap image you want (any width and height) when building mipmapped textures. OpenGL will automatically size it to the proper width and height.
    Warning: Have doubt in anything I post.

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  3. #3
    Join Date
    May 2004
    Even so, you can still load the entire texture and just apply a section of that texture to your quad

  4. #4
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    Ah thanks, the mipmapping thing works wonderful. I have another question though: is it right to use a texture as a background? Because it loads really slow. If a part of the window has been covered and is uncovered, it takes about half a second before the background shows up. Before then, the window is simply white.

  5. #5
    Confused Magos's Avatar
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    Sep 2001
    640 = 512 + 128

    You could split it up in parts (to conserve memory). One 512x512 then one 128x512 to the right. I know Warcraft 3 does this sometimes.

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