osx man page for glscissor

GLSCISSOR(3G)															     GLSCISSOR(3G)

NAME
       glScissor - define the scissor box

C SPECIFICATION
       void glScissor( GLint x,
		       GLint y,
		       GLsizei width,
		       GLsizei height )

PARAMETERS
       x, y Specify the lower left corner of the scissor box.  Initially (0, 0).

       width, height
	    Specify  the  width  and  height of the scissor box.  When a GL context is first attached to a window, width and height are set to the
	    dimensions of that window.

DESCRIPTION
       glScissor defines a rectangle, called the scissor box, in window coordinates.  The first two arguments, x and y,  specify  the  lower  left
       corner of the box.  width and height specify the width and height of the box.

       To  enable  and disable the scissor test, call glEnable and glDisable with argument GL_SCISSOR_TEST. The test is initially disabled.  While
       the test is enabled, only pixels that lie within the scissor box can be modified by drawing commands.  Window coordinates have integer val-
       ues  at	the shared corners of frame buffer pixels.  glScissor(0,0,1,1) allows modification of only the lower left pixel in the window, and
       glScissor(0,0,0,0) doesn't allow modification of any pixels in the window.

       When the scissor test is disabled, it is as though the scissor box includes the entire window.

ERRORS
       GL_INVALID_VALUE is generated if either width or height is negative.

       GL_INVALID_OPERATION is generated if glScissor is executed between the execution of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS
       glGet with argument GL_SCISSOR_BOX
       glIsEnabled with argument GL_SCISSOR_TEST

SEE ALSO
       glEnable, glViewport

																     GLSCISSOR(3G)