glClear

glClear: man3/glClear.xml

glClear sets the bitplane area of the window to values previously selected by glClearColor, glClearDepth, and glClearStencil. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using glDrawBuffer. The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of glClear. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by glClear. glClear takes a single argument that is the bitwise OR of several values indicating which buffer is to be cleared. The values are as follows: The value to which each buffer is cleared depends on the setting of the clear value for that buffer.

If a buffer is not present, then a glClear directed at that buffer has no effect.