glViewport.3gl
Digital Equipment Corporation OpenGL man pages

glViewport.3gl




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
                                                   nd   nd
  device coordinates.  Then the	window coordinates x , y ) are computed as
  follows:					    w	w

                                        width
			    x  = (x  +1)----- + x
			     w	   nd	  2  

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