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.TH "al_orthographic_transform" "3alleg5" "" "Allegro reference manual" ""
.hy
.SH NAME
.PP
al_orthographic_transform \- Allegro 5 API
.SH SYNOPSIS
.IP
.nf
\f[C]
#include\ <allegro5/allegro.h>

void\ al_orthographic_transform(ALLEGRO_TRANSFORM\ *trans,
\ \ \ float\ left,\ float\ top,\ float\ n,
\ \ \ float\ right,\ float\ bottom,\ float\ f)
\f[]
.fi
.SH DESCRIPTION
.PP
Combines the given transformation with an orthographic transformation
which maps the screen rectangle to the given left/top and right/bottom
coordinates.
.PP
near/far is the z range, coordinates outside of that range will get
clipped.
Normally \-1/1 is fine because all 2D graphics will have a z coordinate
of 0.
However if you for example do al_draw_rectangle(0, 0, 100, 100) and
rotate around the x axis (\[lq]towards the screen\[rq]) make sure your z
range allows values from \-100 to 100 or the rotated rectangle will get
clipped.
.PP
Also, if you are using a depth buffer the z range decides the depth
resolution.
For example if you have a 16 bit depth buffer there are only 65536
discrete depth values.
So if your near/far is set to \-1000000/1000000 most of the z positions
would not result in separate depth values which could lead to artifacts.
.SH SINCE
.PP
5.1.3
.SH SEE ALSO
.PP
al_use_projection_transform(3alleg5), al_perspective_transform(3alleg5)