GL library compilation question OS X

Does anyone know how to get the GL library head开发者_开发技巧ers for OS X 10.6 (Snow Leopard)? E.g. I'm getting this error with a sudo port install:

configure: error: You don't seem to have the GL library headers installed.

TIA, Craig

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If you installed the developer tools from the OSX install DVD (xcode, etc), they should have already been installed. If you didn't, you can download a disk image from apple's site of the developer tools installer, then mount it and run the installer to get the GL headers.