Accumulation Buffer

Functions are:

glClear(GL_ACCUM_BUFFER_BIT)

Clear the accumulation buffer

glAccum(GL_ACCUM, factor)

Add frame buffer to accumulation buffer. Contents of color buffer are multiplied by factor.

glAccum(GL_RETURN, factor)

Copy contents of accumulation buffer back to color buffer. Contents are multiplied by factor.

Accumulation buffer is typically 16 bits per component, as compared to 8 bits per component for the color buffer.