[add] with-line macro

2 files changed, 26 insertions, 2 deletions

diff --git a/src/package.lisp b/src/package.lisp
index 57d1aac..73ff610 100644
--- a/src/package.lisp
+++ b/src/package.lisp
@@ -6,8 +6,8 @@
   (:local-nicknames (#:mat #:3d-matrices)
                     (#:vec #:3d-vectors))
   (:import-from #:defclass-std #:defclass/std)
-  (:import-from #:alexandria
-                #:when-let #:when-let* #:if-let)
+  (:import-from #:alexandria-2
+                #:when-let #:when-let* #:if-let #:with-gensyms)
   (:export
    ;; Affine API
    #:height
diff --git a/src/utils.lisp b/src/utils.lisp
index bcb4cb2..ed7be38 100644
--- a/src/utils.lisp
+++ b/src/utils.lisp
@@ -103,3 +103,27 @@ the path."
                      :width (- max-x min-x)
                      :height (- max-y min-y)))))
 
+(defmacro setf-many (places-and-value)
+  "e.g. (setf-many a b c 10) would set a b and c to 10"
+  (let ((value-form
+          (first (last places-and-value))))
+    `(setf ,@(butlast places-and-value) ,value-form)))
+
+
+(defmacro with-line
+    ((x y) (start-x start-y) (end-x end-y) &body body)
+  "Execute BODY for X and Y assigned to integer values in a line
+connecting the integer point START-X , START-Y and END-X, END-Y. "
+  (with-gensyms (sx sy ex ey distance step progress xdiff ydiff)
+    `(let* ((,sx ,start-x)
+            (,sy ,start-y)
+            (,ex ,end-x)
+            (,ey ,end-y)
+            (,xdiff (- ,ex ,sx))
+            (,ydiff (- ,ey ,sy))
+            (,distance (max (abs ,xdiff) (abs ,ydiff))))
+       (loop for ,step from 0 to ,distance
+             for ,progress = (if (zerop ,distance) 0.0 (/ ,step ,distance))
+             for ,x = (round (+ ,start-x (* ,progress ,xdiff)))
+             for ,y = (round (+ ,start-y (* ,progress ,ydiff)))
+             do (progn ,@body)))))