106 lines
2.9 KiB
Plaintext
106 lines
2.9 KiB
Plaintext
'\" e
|
|
'\"! eqn | mmdoc
|
|
'\"macro stdmacro
|
|
.ds Vn Version 1.2
|
|
.ds Dt 24 September 1999
|
|
.ds Re Release 1.2.1
|
|
.ds Dp Jan 14 18:30
|
|
.ds Dm 01 ortho.gl
|
|
.ds Xs 2001 5 ortho.gl
|
|
.TH GLORTHO 3G
|
|
.SH NAME
|
|
.B "glOrtho
|
|
\- multiply the current matrix with an orthographic matrix
|
|
|
|
.SH C SPECIFICATION
|
|
void \f3glOrtho\fP(
|
|
GLdouble \fIleft\fP,
|
|
.nf
|
|
.ta \w'\f3void \fPglOrtho( 'u
|
|
GLdouble \fIright\fP,
|
|
GLdouble \fIbottom\fP,
|
|
GLdouble \fItop\fP,
|
|
GLdouble \fInear_val\fP,
|
|
GLdouble \fIfar_val\fP )
|
|
.fi
|
|
|
|
.SH PARAMETERS
|
|
.TP \w'\f2left\fP\ \f2right\fP\ \ 'u
|
|
\f2left\fP, \f2right\fP
|
|
Specify the coordinates for the left and right vertical clipping planes.
|
|
.TP
|
|
\f2bottom\fP, \f2top\fP
|
|
Specify the coordinates for the bottom and top horizontal clipping planes.
|
|
.TP
|
|
\f2near_val\fP, \f2far_val\fP
|
|
Specify the distances to the nearer and farther depth clipping planes.
|
|
These values are negative if the plane is to be behind the viewer.
|
|
.SH DESCRIPTION
|
|
\%\f3glOrtho\fP describes a transformation that produces a parallel projection.
|
|
The current matrix (see \%\f3glMatrixMode\fP) is multiplied by this matrix
|
|
and the result replaces the current matrix, as if
|
|
\%\f3glMultMatrix\fP were called with the following matrix
|
|
as its argument:
|
|
.sp
|
|
.ce
|
|
.EQ
|
|
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 )
|
|
.EN
|
|
.BP
|
|
.P
|
|
where
|
|
.ce
|
|
.EQ
|
|
t sub x ~=~ -^{{"right" ~+~ "left"} over {"right" ~-~ "left"}}
|
|
.EN
|
|
|
|
.ce
|
|
.EQ
|
|
t sub y ~=~ -^{{"top" ~+~ "bottom"} over {"top" ~-~ "bottom"}}
|
|
.EN
|
|
|
|
.ce
|
|
.EQ
|
|
t sub z ~=~ -^{{"far_val" ~+~ "near_val"} over {"far_val" ~-~ "near_val"}}
|
|
.EN
|
|
|
|
.RE
|
|
.P
|
|
Typically, the matrix mode is \%\f3GL_PROJECTION\fP, and
|
|
(\f2left\fP, \f2bottom\fP, \-\f2near_val\fP) and (\f2right\fP, \f2top\fP, \-\f2near_val\fP)
|
|
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_val\fP specifies the location of the far clipping plane.
|
|
Both \f2near_val\fP and \f2far_val\fP can be either positive or negative.
|
|
.P
|
|
Use \%\f3glPushMatrix\fP and \%\f3glPopMatrix\fP to save and restore
|
|
the current matrix stack.
|
|
.SH ERRORS
|
|
\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glOrtho\fP
|
|
is executed between the execution of
|
|
\%\f3glBegin\fP
|
|
and the corresponding execution of \%\f3glEnd\fP.
|
|
.SH ASSOCIATED GETS
|
|
\%\f3glGet\fP with argument \%\f3GL_MATRIX_MODE\fP
|
|
.br
|
|
\%\f3glGet\fP with argument \%\f3GL_COLOR_MATRIX\fP
|
|
.br
|
|
\%\f3glGet\fP with argument \%\f3GL_MODELVIEW_MATRIX\fP
|
|
.br
|
|
\%\f3glGet\fP with argument \%\f3GL_PROJECTION_MATRIX\fP
|
|
.br
|
|
\%\f3glGet\fP with argument \%\f3GL_TEXTURE_MATRIX\fP
|
|
.SH SEE ALSO
|
|
\%\f3glFrustum(3G)\fP,
|
|
\%\f3glMatrixMode(3G)\fP,
|
|
\%\f3glMultMatrix(3G)\fP,
|
|
\%\f3glPushMatrix(3G)\fP,
|
|
\%\f3glViewport(3G)\fP
|