make-transform Function

Summary

Returns a new transform object initialized according to a set of optional arguments.

Package

graphics-ports

Signature

make-transform &optional a b c d e f => transform

Arguments

a⇩, b⇩, c⇩, d⇩, e⇩, f⇩
	Real numbers.

Values

transform

A transform object.

Description

The function make-transform returns a new transform object initialized according to the optional args. The default args make the unit transform.

Default values are as follows: a and d are 1; b, c, e, and f are 0. The transform matrix is:

a  b  0
c  d  0
e  f  1

for generalized two dimensional points of the form (x y 1).

Notes

See graphics-state for details of how a transform is used.

Examples

This transform will cause rotation by pi/4 radians:

(let ((s (sin (/ pi 4)))
      (c (cos (/ pi 4))))
  (gp:make-transform  c  s (- s) c 0 0))

See also

graphics-state
transform