glClear

NAME

glClear -- clear buffers within the viewport

C SPECIFICATION

void glClear(GLbitfield mask)

PARAMETERS

mask: Bitwise OR of masks that indicate the buffers to be cleared. The four masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, GL_ACCUM_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT.

DESCRIPTION

glClear sets the bitplane area of the viewport to values previously selected by glClearIndex, glClearStencil, and 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 z-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:

GL_COLOR_BUFFER_BIT: Indicates the buffers currently enabled for color writing.
GL_DEPTH_BUFFER_BIT: Indicates the depth buffer.
GL_ACCUM_BUFFER_BIT: Indicates the accumulation buffer.
GL_STENCIL_BUFFER_BIT: Indicates the stencil buffer.

The value to which each buffer is cleared depends on the setting of the clear value for that buffer.

NOTES

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

ERRORS

GL_INVALID_VALUE is generated if any bit other than the four defined bits is set in mask.

GL_INVALID_OPERATION is generated if glClear is called between a call to glBegin and the corresponding call to glEnd.

ASSOCIATED GETS

glGet with argument GL_ACCUM_CLEAR_VALUE
glGet with argument GL_DEPTH_CLEAR_VALUE
glGet with argument GL_INDEX_CLEAR_VALUE
glGet with argument GL_COLOR_CLEAR_VALUE
glGet with argument GL_STENCIL_CLEAR_VALUE