Porting Accumulation Buffer Calls

You must allocate your accumulation buffer by requesting the appropriate pixel format with the OpenGL auxInitDisplayMode or ChoosePixelFormat function. The following table lists IRIS GL functions that affect the accumulation buffer and their equivalent OpenGL functions.

IRIS GL Function OpenGL Function Meaning
acsize auxInitDisplayMode or ChoosePixelFormat Specify number of bitplanes per color component in the accumulation buffer.
acbuf glAccum Operate on the accumulation buffer.
glClearAccum Set clear values for accumulation buffer.
acbuf(AC_CLEAR) glClear(GL_ACCUM_BUFFER_BIT) Clear the accumulation buffer.

The following table lists the IRIS GL acbuf parameters along with the equivalent OpenGL glAccum parameters.

IRIS GL Parameter OpenGL Parameter
AC_ACCUMULATE GL_ACCUM
AC_CLEAR_ACCUMULATE GL_LOAD
AC_RETURN GL_RETURN
AC_MULT GL_MULT
AC_ADD GL_ADD