redhat man page for glortho

GLORTHO(3G)															       GLORTHO(3G)

NAME
       glOrtho - multiply the current matrix with an orthographic matrix

C SPECIFICATION
       void glOrtho( GLdouble left,
		     GLdouble right,
		     GLdouble bottom,
		     GLdouble top,
		     GLdouble near_val,
		     GLdouble far_val )

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

DESCRIPTION
       glOrtho describes a transformation that produces a parallel projection.	The current matrix (see glMatrixMode) is multiplied by this matrix
       and the result replaces the current matrix, as if glMultMatrix were called with the following matrix as its argument:

							__________	0	      0        tx
						       (    0	   __________	      0        ty)
							    0	       0      ________________ tz
							    0	       0	     0	       1
       where
								     tx=-__________

								     ty=-__________

								  tz=-________________

       Typically,  the	matrix	mode  is GL_PROJECTION, and (left, bottom,  -near_val) and (right, top,  -near_val) 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_val specifies the location of the far clipping plane.  Both near_val and far_val can be either positive or negative.

       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_COLOR_MATRIX
       glGet with argument GL_MODELVIEW_MATRIX
       glGet with argument GL_PROJECTION_MATRIX
       glGet with argument GL_TEXTURE_MATRIX

SEE ALSO
       glFrustum(3G), glMatrixMode(3G), glMultMatrix(3G), glPushMatrix(3G), glViewport(3G)

																       GLORTHO(3G)