Define rotation transform

2025-05-29 01:14:30 +01:00 · 2025-05-29 01:14:30 +01:00 · 668d369943
commit 668d369943
parent 8738229053
1 changed files with 4 additions and 0 deletions
--- a/drawing.lisp
+++ b/drawing.lisp
@ -61,6 +61,10 @@
                  :y-transform (* scale-factor y)
                  :scalar-transform (* scale-factor s))

+(define-transform rotate (theta)
+                  :x-transform (- (* x (cos theta)) (* y (sin theta)))
+                  :y-transform (+ (* x (sin theta)) (* y (cos theta))))
+
 (defun overlay (&rest drawings)
  (apply #'append drawings))