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Rectangle Textures

Started by Gergo Aug 10, 2007 at 5:02 AM 3 replies 900+ views

Original Post

Aug 10, 2007 at 5:02 AM

Hi! I'm trying to use the GL_ARB_texture_rectangle extension, but I get strange results. In theory my card supports this extension (it's in the extension string). This is what it looks like: http://img406.imageshack.us/my.php?image=error2se9.jpg This is an image of a landscape, but it becomes grayscale, and scrambled. I don't use mipmaps, and the texture coordinate wrap is gl_clamp, and I specify the texcoords in the [0..w]x[0..h] range... Does anyone encountered something like this? Any suggestions would be appreciated.

nmi

Aug 10, 2007 at 6:07 AM

How do you create the texture in your application ? Maybe you are using the wrong storage format for the data.

Gergo

Author

Gergo

Aug 10, 2007 at 7:59 AM

This code loads the textures:

glGenTextures(1,&id);
glBindTexture(target,id);
glTexParameteri(target,GL_TEXTURE_MAG_FILTER,magfilt);
glTexParameteri(target,GL_TEXTURE_MIN_FILTER,minfilt);
glTexParameteri(target,GL_TEXTURE_WRAP_S,GL_CLAMP);
glTexParameteri(target,GL_TEXTURE_WRAP_T,GL_CLAMP);
glTexImage2D(target,0,type,f_width,f_height,border,type,GL_UNSIGNED_BYTE,img->Pixel(0,0));

where target is GL_TEXTURE_2D if both f_width and f_height are power of two, otherwise it's GL_TEXTURE_RECTANGLE_ARB. type is GL_RGB, border is 0.

nmi

Aug 10, 2007 at 8:29 AM

Just some ideas which you might try:
1) Is the texture you provide to glTexImage2D() really a 24 bit RGB texture or does it contain alpha ?
2) Did you glEnable(GL_TEXTURE_RECTANGLE_ARB) ?
3) Are you using shaders ? Then use: "uniform Sampler2DRect Texture0; ... texture2DRect(Texture0, vec2(gl_TexCoord[0]));"
4) Are you using borders ? They are not supported for rectangular textures.

Gergo

Author

Gergo

Aug 10, 2007 at 10:32 AM

Thanks guys for the help, it turned out that even though the dimensions don't have to be power of two, they must be divisible by 2 :D

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