glViewport(3G)		       OpenGL Reference			glViewport(3G)



NAME
     glViewport	- set the viewport


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


PARAMETERS
     x,	y Specify the lower left corner	of the viewport	rectangle, in pixels.
	  The default is (0,0).

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

DESCRIPTION
     glViewport	specifies the affine transformation of x and y from normalized
     device coordinates	to window coordinates.	Let (x	, y  ) be normalized
     device coordinates.  Then the window coordinates (x , yd) are computed as
     follows:						w   w

			      x	 = (x  +1)(_____) + x
			       w     nd	  (  2	)
			     y	= (y  +1)(______) + y
			      w	    nd	 (  2	)
     Viewport width and	height are silently clamped to a range that depends on
     the implementation.  This range is	queried	by calling glGet with argument
     GL_MAX_VIEWPORT_DIMS.

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

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

ASSOCIATED GETS
     glGet with	argument GL_VIEWPORT
     glGet with	argument GL_MAX_VIEWPORT_DIMS


SEE ALSO
     glDepthRange








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