Texturing on a rectangle
April 02, 2005 12:25 PM
Hello,
I have refered to NEHE example 6 about texturizing quads, but what I plan on doing is just texturing a quad on just one side. Problem I am having is that the image I have is a rectangle with a width of 576 pixels, and height of 360 pixels. I load the image and all that and I assume the area of concern for this is within this code:
glTexCoord2f(0.0f, 0.0f); glVertex2f(-1.0f, -1.0f);
glTexCoord2f(1.0f, 0.0f); glVertex2f( 1.0f, -1.0f);
glTexCoord2f(1.0f, 0.625f); glVertex2f( 1.0f, 1.0f);
glTexCoord2f(0.0f, 0.625f); glVertex2f(-1.0f, 1.0f);
Is there any sort of formula available to determine the values for both glTexCoord2f and glVertex2f? Or am I doing this wrong? It displays a white square.
Thankyou, Jamie
235
April 02, 2005 12:35 PM
Your texture size is non-power of 2, which means that either the width or the height - or both - isn't 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048 etc. pixels wide.
OpenGL only accepts power of 2 textures (others can be loaded via an extension, but I think that's only for newer cards - but standard only accepts power of 2).
OpenGL only accepts power of 2 textures (others can be loaded via an extension, but I think that's only for newer cards - but standard only accepts power of 2).
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436
April 02, 2005 12:48 PM
exactly, resize it to 512x256 and it will probobly work just fine.
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122
April 02, 2005 02:22 PM
so far i never use glvertex2f. i think glvertex2f is used to draw to 2D image.
April 03, 2005 02:08 PM
Is there a way to work around the fact that openGL only accepts power of 2 textures?
-Jamie
-Jamie
134
April 03, 2005 02:54 PM
There are extensions to allow the use of oddly size texutures but you are best to stick to the rule as that is guaranteed.
If texturing 2D planes (sprites) then you could just pad your texture with a dedicated invisible colour.
If texturing 2D planes (sprites) then you could just pad your texture with a dedicated invisible colour.
451
April 03, 2005 06:47 PM
Quote: Original post by ACSRalphie
Is there a way to work around the fact that openGL only accepts power of 2 textures?
-Jamie
Quote: From Lesson7
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.
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