fglOrtho(3G) OpenGL Reference fglOrtho(3G)NAMEfglOrtho - multiply the current matrix with an orthographic matrix
FORTRAN SPECIFICATION
SUBROUTINE fglOrtho( REAL*4 left,
REAL*4 right,
REAL*4 bottom,
REAL*4 top,
REAL*4 near,
REAL*4 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 values are negative if the plane is
to be behind the viewer.
DESCRIPTIONfglOrtho describes a transformation that produces a parallel projection.
The current matrix (see fglMatrixMode) is multiplied by this matrix and
the result replaces the current matrix, as if fglMultMatrix were called
with the following matrix as its argument:
( )
__________
| 0 0 t |
right-left x
| |
| __________ |
0 0 t
| top-bottom y |
| |
________
| 0 0 t |
far-near z
| |
| 0 0 0 1 |
( )
where
____________
t = -
x right - left
____________
t = -
y top - bottom
__________
t = -
z far - near
Typically, the matrix mode is GL_PROJECTION, and (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
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fglOrtho(3G) OpenGL Reference fglOrtho(3G)
specifies the location of the far clipping plane. Both near and far can
be either positive or negative.
Use fglPushMatrix and fglPopMatrix to save and restore the current matrix
stack.
ERRORS
GL_INVALID_OPERATION is generated if fglOrtho is executed between the
execution of fglBegin and the corresponding execution of fglEnd.
ASSOCIATED GETS
fglGet with argument GL_MATRIX_MODE
fglGet with argument GL_COLOR_MATRIX
fglGet with argument GL_MODELVIEW_MATRIX
fglGet with argument GL_PROJECTION_MATRIX
fglGet with argument GL_TEXTURE_MATRIX
SEE ALSO
fglFrustum, fglMatrixMode, fglMultMatrix, fglPushMatrix, fglViewport
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