How to use texture compression in openGL?

Question

I'm making an image viewer using openGL and I've run into a situation where I need to load very large (>50MB) images to be viewed. I'm loading the images as textures and displaying them to a GL_QUAD which has been working great for smaller images, but on the large images the loading fails and I get a blank rectangle. So far I've implemented a very ugly hack that uses another program to convert the images to smaller, lower resolution versions which can be loaded, but I'm looking for a more elegant solution. I've found that openGL has a texture compression feature but I can't get it to work. When I call

glTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGBA_ARB, t.width(), t.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, t.bits());

I get the compiler error "*GL_COMPRESSED_RGBA_ARB* undeclared". What am I doing wrong? Is there a library I'm missing? And more generally, is this a viable solution to my problem?

I'm using Qt Creator on a Windows Vista machine, with a NVIDIA Quadro FX 1700 graphics card.

Answer 1

First, I'd have to ask what resolution are these large images? Secondly, to use a define such as GL_COMPRESSED_RGBA_ARB, you would need to download and use something like GLEW which is more modernized in the GL api than the standard MS-Dev install.

Answer 2

On my own GFX card the maximum resolution for an opengl texture is 8192x8192, if your image is bigger then 50MB, it is propably a very very high resolution... Check http://www.opengl.org/resources/faq/technical/texture.htm , it describes how you can find the maximum texture size.