glClear.3gl

Name

  glClear - clear buffers to preset values

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	window to values previously selected
  by glClearColor, glClearIndex, glClearDepth, glClearStencil, and
  glClearAccum.	 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 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 executed between the
  execution of glBegin and the corresponding execution of 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

See Also

  glClearAccum,	glClearColor, glClearDepth, glClearIndex, glClearStencil,
  glDrawBuffer,	glScissor

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Last Edited: Fri Dec 6 11:18:03 EST 1996 by AFV
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