glOrtho(3G)		       OpenGL Reference			   glOrtho(3G)



NAME
     glOrtho - multiply	the current matrix by an orthographic matrix


C SPECIFICATION
     void glOrtho( GLdouble left,
		   GLdouble right,
		   GLdouble bottom,
		   GLdouble top,
		   GLdouble near,
		   GLdouble far	)


PARAMETERS
     left, right Specify the coordinates for the left and right	vertical
		 clipping planes.

     bottom, top Specify the coordinates for the bottom	and top	horizontal
		 clipping planes.

     near, far	 Specify the distances to the nearer and farther depth
		 clipping planes.  These distances are negative	if the plane
		 is to be behind the viewer.


DESCRIPTION
     glOrtho describes a matrix	that produces a	parallel projection.  (left,
     bottom,  -near) and (right, top,  -near) specify the points on the	near
     clipping plane that are mapped to the lower left and upper	right corners
     of	the window, respectively, assuming that	the eye	is located at (0, 0,
     0).  -far specifies the location of the far clipping plane.  Both near
     and far can be either positive or negative.  The corresponding matrix is
		      (					   )
		      |__________      0	  0	 t |
		      |right-left			  x|
		      |		   __________		   |
		      |	   0	   top-bottom	  0	 ty|
		      |					   |
		      |	   0	       0       ________	 t |
		      |			       far-near	  z|
		      |	   0	       0	  0	 1 |
		      (					   )

     where
				 t  = -__________
				  x    right-left
				 t  = -__________
				  y    top-bottom
				  t  = -________
				   z	far-near
     The current matrix	is multiplied by this matrix with the result replacing
     the current matrix.  That is, if M	is the current matrix and O is the



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glOrtho(3G)		       OpenGL Reference			   glOrtho(3G)



     ortho matrix, then	M is replaced with M o O.

     Use glPushMatrix and glPopMatrix to save and restore the current matrix
     stack.

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

ASSOCIATED GETS
     glGet with	argument GL_MATRIX_MODE
     glGet with	argument GL_MODELVIEW_MATRIX
     glGet with	argument GL_PROJECTION_MATRIX
     glGet with	argument GL_TEXTURE_MATRIX


SEE ALSO
     glFrustum,	glMatrixMode, glMultMatrix, glPushMatrix, glViewport





































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