glClear(3G)		       OpenGL Reference			   glClear(3G)

NAME    [Toc]    [Back]

     glClear - clear buffers to	preset values

C SPECIFICATION    [Toc]    [Back]

     void glClear( GLbitfield mask )

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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 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:

     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    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     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.




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glClear(3G)		       OpenGL Reference			   glClear(3G)

ASSOCIATED GETS    [Toc]    [Back]

     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    [Toc]    [Back]

     glClearAccum, glClearColor, glClearDepth, glClearIndex, glClearStencil,
     glColorMask, glDepthMask, glDrawBuffer, glScissor,	glStencilMask


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