OpenGL man pages
glPassThrough - place a marker in the feedback buffer
void glPassThrough( GLfloat token )
token Specifies a marker value to be placed in the feedback buffer
following a GL_PASS_THROUGH_TOKEN.
Feedback is a GL render mode. The mode is selected by calling glRenderMode
with GL_FEEDBACK. When the GL is in feedback mode, no pixels are produced
by rasterization. Instead, information about primitives that would have
been rasterized is fed back to the application using the GL. See
glFeedbackBuffer for a description of the feedback buffer and the values in
glPassThrough inserts a user-defined marker in the feedback buffer when it
is executed in feedback mode. token is returned as if it were a primitive;
it is indicated with its own unique identifying value:
GL_PASS_THROUGH_TOKEN. The order of glPassThrough commands with respect to
the specification of graphics primitives is maintained.
glPassThrough is ignored if the GL is not in feedback mode.
GL_INVALID_OPERATION is generated if glPassThrough is executed between the
execution of glBegin and the corresponding execution of glEnd.
glGet with argument GL_RENDER_MODE
Fri Dec 6 11:18:03 EST 1996
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