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 |