Reference Manual glFeedbackBuffer Subroutine Purpose Controls the feedback mode. Description The glFeedbackBuffer subroutine controls feedback. Feedback, like selection, is a GL mode. When the GL is in feedback mode, no pixels are produced by rasterization. Size indicates the size of the array.
Type is a symbolic constant describing the information that is fed back for each vertex.
When this is done while the GL is in feedback mode, glRenderMode returns the number of entries placed in the feedback array. The returned value never exceeds Size . If the feedback data requires more room than is available in Buffer , glRenderMode returns a negative value. While in feedback mode, each primitive that would be rasterized generates a block of values that get copied into the feedback array. Each block begins with a code indicating the primitive type, followed by values that describe the primitive's vertices and associated data.