GLORTHO

NAME

glOrtho - multiply the current matrix with an orthographic matrix

C SPECIFICATION

void f3glOrthofP( GLdouble fIleftfP,

f2leftfP, f2rightfP
Specify the coordinates for the left and right vertical clipping planes.

f2bottomfP, f2topfP
Specify the coordinates for the bottom and top horizontal clipping planes.
f2near_valfP, f2far_valfP
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

%f3glOrthofP describes a transformation that produces a parallel projection. The current matrix (see %f3glMatrixModefP) is multiplied by this matrix and the result replaces the current matrix, as if %f3glMultMatrixfP were called with the following matrix as its argument:

left ( matrix {
   ccol { {2 over {"right" - "left"}} above 0 above 0 above 0 }
   ccol { 0 above {2 over {"top" - "bottom"}} above 0 above 0 }
   ccol { 0 above 0 above {-2 over {"far_val" - "near_val"}}  above 0 }
   ccol { {t sub x}~ above {t sub y}~ above {t sub z}~ above 1~ } } right ) where
t sub x ~=~ -^{{"right" ~+~ "left"} over {"right" ~-~ "left"}}

t sub y ~=~ -^{{"top" ~+~ "bottom"} over {"top" ~-~ "bottom"}}

t sub z ~=~ -^{{"far_val" ~+~ "near_val"} over {"far_val" ~-~ "near_val"}}

Typically, the matrix mode is %f3GL_PROJECTIONfP, and (f2leftfP, f2bottomfP, -f2near_valfP) and (f2rightfP, f2topfP, -f2near_valfP) 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). -f2far_valfP specifies the location of the far clipping plane. Both f2near_valfP and f2far_valfP can be either positive or negative. Use %f3glPushMatrixfP and %f3glPopMatrixfP to save and restore the current matrix stack.

ERRORS

%f3GL_INVALID_OPERATIONfP is generated if %f3glOrthofP is executed between the execution of %f3glBeginfP and the corresponding execution of %f3glEndfP.

ASSOCIATED GETS

%f3glGetfP with argument %f3GL_MATRIX_MODEfP
%f3glGetfP with argument %f3GL_COLOR_MATRIXfP
%f3glGetfP with argument %f3GL_MODELVIEW_MATRIXfP
%f3glGetfP with argument %f3GL_PROJECTION_MATRIXfP
%f3glGetfP with argument %f3GL_TEXTURE_MATRIXfP