EGL and GLUT

When you create a GL context with EGL, you can specify what configuration of framebuffers you want bound to that context. You can find an appropriate configuration with eglChooseConfig, which will return a number of configurations which match the attributes you specify. If there are no valid configurations, then it will return none.

You can use this mechanism to specify whether you need an alpha channel, how many bits of RGB channel, whether you need a depth buffer or a stencil buffer. Note that in the PSP hardware, the stencil buffer and the destination alpha channel share the same space, so you can have one or the other for a given GL context.

GLUT is simpler to use, and so does not let you specify fine details of the GL configuration; it will always request 8 bits of RGB. You can use the GLUT_RGB, GLUT_ALPHA, GLUT_STENCIL and GLUT_DEPTH flags to glutInitDisplayMode to specify a buffer configuration.