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Techniques for Choosing Attributes

Renderer and buffer attributes determine the renderers that the system chooses for your application. Each of the Apple-specific OpenGL APIs provides constants that specify a variety of renderer and buffer attributes. You supply a list of attribute constants to one of the Apple OpenGL functions for choosing a pixel format object. The pixel format object maintains a list of appropriate renderers. In previous chapters, you saw how to set up an attributes array that contains a small set of attributes.

In a real-world application, selecting attributes is an art because you don't know the exact combination of hardware and software that your application will run on. An attribute list that is too restrictive could miss out on future capabilities or not be able to run on many systems. For example, if you specify a buffer of a specific depth, your application won't be able to take advantage of a larger buffer when more memory is available in the future. In this case, you might specify a required minimum and direct OpenGL to use the maximum available.

Although you might want to specify attributes that make your OpenGL content look and run its best, you also need to consider whether you'll allow your application to run on a less-capable system at the expense of speed or detail. If tradeoffs are acceptable, you'll need to set the attributes accordingly.

Contents:

Buffer Size Attribute Selection Tips
Attributes that are not Recommended
Ensuring that Back Buffer Contents Remain the Same
Ensuring a Valid Pixel Format Object
Ensuring a Specific Type of Renderer
Ensuring a Single Renderer for a Display
See Also

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