View Full Version : glTexImage2D problem with a large image
02-02-2009, 04:41 AM
Displaying an image from 8192 x 300 pixels is no problem with
glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, ImageWidth, ImageHeight, 0,GL_LUMINANCE, GL_UNSIGNED_SHORT, addr(WordBuffer));
But if I use this same function with an image of 12288 x 300 pixels nothing is being displayed.
Any idea why this is?
Is 12288 to large?
02-02-2009, 04:49 AM
Textures have size limitation, check for it with:
glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size);
02-02-2009, 07:43 AM
glGetError returns GL_INVALID_VALUE.
Is glDrawPixels capable of displaying a large image?
In the past I used glTexImage2D because I wanted to manipulate the image on screen like glRotatef, glScalef and glTranslatef.
Are these functions also avaible for glDrawPixels?
As already said, check glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size), that will tell you the maximum size, that is supported by your particular GPU.
However, to spoil the fun, i will tell you that there is currently no GPU that supports textures bigger than 8192 pixels in any one direction.
02-03-2009, 01:02 AM
You're right. I tried glGetIntegerv (GL_MAX_TEXTURE_SIZE, &max_texture_size) but it returned 91537540. Bud I made an error.
I correct it and now it's returning 8192.
I have modifed my code, so I replaced glTexImage2D by glDrawPixels. The first test shows an image of 12288 x 300.
Unfortunately the frame rate drops when zooming out (whole image on screen). Frame rate drops from 60Hz to 20Hz.
Thanks all for your help.
02-03-2009, 03:15 AM
stay away from drawpixels.
just split your texture in several tiles.
02-03-2009, 05:37 AM
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