fgluPickMatrix man page on IRIX

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fgluPickMatrix(3G)	       OpenGL Reference		    fgluPickMatrix(3G)

NAME
     fgluPickMatrix - define a picking region

FORTRAN SPECIFICATION
     SUBROUTINE fgluPickMatrix( REAL*4 x,
				REAL*4 y,
				REAL*4 delX,
				REAL*4 delY,
				CHARACTER*8 viewport )

PARAMETERS
     x, y Specify the center of a picking region in window coordinates.

     delX, delY
	  Specify the width and height, respectively, of the picking region in
	  window coordinates.

     viewport
	  Specifies the current viewport (as from a glGetIntegerv call).

DESCRIPTION
     fgluPickMatrix creates a projection matrix that can be used to restrict
     drawing to a small region of the viewport.	 This is typically useful to
     determine what objects are being drawn near the cursor.  Use
     fgluPickMatrix to restrict drawing to a small region around the cursor.
     Then, enter selection mode (with glRenderMode) and rerender the scene.
     All primitives that would have been drawn near the cursor are identified
     and stored in the selection buffer.

     The matrix created by fgluPickMatrix is multiplied by the current matrix
     just as if glMultMatrix is called with the generated matrix.  To
     effectively use the generated pick matrix for picking, first call
     glLoadIdentity to load an identity matrix onto the perspective matrix
     stack.  Then call fgluPickMatrix, and finally, call a command (such as
     fgluPerspective) to multiply the perspective matrix by the pick matrix.

     When using fgluPickMatrix to pick NURBS, be careful to turn off the NURBS
     property GLU_AUTO_LOAD_MATRIX.  If GLU_AUTO_LOAD_MATRIX is not turned
     off, then any NURBS surface rendered is subdivided differently with the
     pick matrix than the way it was subdivided without the pick matrix.

									Page 1

fgluPickMatrix(3G)	       OpenGL Reference		    fgluPickMatrix(3G)

EXAMPLE
     When rendering a scene as follows:

	  glMatrixMode(GL_PROJECTION);
	  glLoadIdentity();
	  gluPerspective(...);
	  glMatrixMode(GL_MODELVIEW);
	  /* Draw the scene */

     a portion of the viewport can be selected as a pick region like this:

	  glMatrixMode(GL_PROJECTION);
	  glLoadIdentity();
	  gluPickMatrix(x, y, width, height, viewport);
	  gluPerspective(...);
	  glMatrixMode(GL_MODELVIEW);
	  /* Draw the scene */

SEE ALSO
     glGet, glLoadIndentity, glMultMatrix, glRenderMode, fgluPerspective

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