MirOS Manual: glClear(3)


GLCLEAR(3G)         UNIX Programmer's Manual          GLCLEAR(3G)

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 pre-
     viously 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

     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.

MirOS BSD #10-current   Printed 20.2.2012                       1

GLCLEAR(3G)         UNIX Programmer's Manual          GLCLEAR(3G)

     GL_INVALID_OPERATION is generated if glClear is executed
     between the execution of glBegin and the corresponding exe-
     cution 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(3G), glClearColor(3G), glClearDepth(3G),
     glClearIndex(3G), glClearStencil(3G), glColorMask(3G),
     glDepthMask(3G), glDrawBuffer(3G), glScissor(3G),
     glStencilMask(3G)

MirOS BSD #10-current   Printed 20.2.2012                       2

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