Strange issues with texture mapping

I am attempting to use texture coordinates from a pre-generated PNG file on a 3d world of quads loaded into Java with LWJGL's slick-util extension.

The texture file is 192x96pixels, and properly formatted. It's composed of 6x3 32x32 tiles.

The 3d quads are 1.5f wi开发者_如何学Pythonde and long. They are spaced apart properly.

I am having issues getting the right texture coordinates. When I put 0.0f to 0.333333f as the y coordinates, I get slightly more than the top tile's height displayed. However, if I put 0.0f-0.25f, I get exactly 1/3rd, which is my tile's height. I have yet to find a magic number for the X coordinates, but maybe someone could explain to me why 1/4 of 96 is 24 according to textures coordinates, or what I'm doing wrong? I'm suspecting it could be a clash between my quad size and textures.

The tops of the cubes are using the texture coordinates (0.0, 0.0f), (0.0, 0.333333f), (0.166666f, 0.333333f), (0.166666f, 0.0f), which is applied moving anticlockwise from the top left to the top right. Again, the main texture file is 32x32 tiles arranged to make 192x96(96 is the height).

Notice I placed a white line at the top of one of the tiles to see its border, and black line at it's bottom, then a white line for the top of the next one below it. The texture 'bleeds' too far down. The other textures have their own even stranger coordinates, as you can see.

Arranging texture coordinates with the assumption the top of the image is 1.0 rather than the bottom produces odd squares with a rectangular hole in the center where quads should be.

I am using TEX_ENV GL_MODULATE.

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Texture sizes are usually a power of 2. I suspect something resized your 192x96 texture as a 256x128 or 256x256 texture. This doesn't really explain the values you found however... But, I think, if you resize your texture to 256x256(increase the size, don't scale!) and calculate your texture coordinates based on that, your problem will go away.

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I don't know about java but with my image atlases in objective C and openGL ES you need to make the textures smaller than what you are referring to when selecting them from the atlas.

Have you left a sufficient gap between the texture images to prevent 'bleeding?