every introduction and sample that I can find seems to use GLUT or some other framework to "initialize" OpenGL. Is there a way of initializing OpenGL with just what is available in GL and GLU? If not, then what is GLUT doing that is not possible without it?
7 Answers
As luke noted, the code to create and bind the context is specific to each windowing platform.
Here are some functions to get you started in terms of initializing OpenGL on specific platforms:
Windows (a tutorial is here)
- wglCreateContext(hDC)
Mac OS X -- OS X has essentially three options: Carbon, Cocoa, and the underlying Core Graphics Layer
- The entire guide for Mac OS X OpenGL development
- Carbon: aglCreateContext
- Cocoa: Create (or subclass) an NSOpenGLView. They create their own context, and you can read their method documentation to find how to make it current.
- CoreGraphicsLayer: CGLCreateContext
Linux
- glx: glXCreateContext
What you're doing is initializing a window with an OpenGL context. This requires some calls to the operating system. It is not possible to initialize OpenGL with just gl.h and glu.h. GLUT (or SDL, SMFL, etc) does that work for you in a nice platform independent way. You can do the initialization with native calls as well.
You could grab the GLUT source code and see the init code for whatever platform you are concerned with.
GL is an API, and GLU is an utility library on top of GL. It's completely operating system independent.
OpenGL initialization and extension fetching are platform dependent operations. Therefore you can do about nothing with OpenGL alone.
GLUT is fast insufficient and terribly poor library, and about only it does is that it initializes the opengl context and provides some primitive mouse/keyboard input modules to get you ongoing.
Win32 provides tools to initialize opengl context as well. For linux you could check out GLX. Also, if you want a system independent way of doing it, then you could check out SDL. For different programming languages there may be utilities that provide you a platform independent desktop API.
Here's a basic and good introduction to how you initialize OpenGL (assuming windows) without using GLUT:
As Luke said, if you dont want to use GLUT, you need specific information about the operating system you are developing on. Using GLUT will make your code easier to port.
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