Add ortho line

src/crypts-and-corpses.lisp

@@ -375,6 +375,46 @@
               collect coord into coords
               finally (return coords))))))
 
+;; trivial-ortho-line and ortho-line written by vydd
+;; https://github.com/vydd/
+;; Ported from https://github.com/SquidPony/SquidLib/blob/master/squidlib-util/src/main/java/squidpony/squidmath/OrthoLine.java
+(defun trivial-ortho-line (start-x start-y end-x end-y)
+  (let ((start-x (min start-x end-x))
+        (end-x (max start-x end-x))
+        (start-y (min start-y end-y))
+        (end-y (max start-y end-y)))
+    (cond ((and (= start-x end-x) (= start-y end-y)) `((,start-x ,start-y)))
+          ((= start-x end-x) (loop for y from start-y upto end-y
+                                   collect `(,start-x ,y)))
+          ((= start-y end-y) (loop for x from start-x upto end-x
+                                   collect `(,x ,start-y))))))
+
+(defun ortho-line (start-x start-y end-x end-y)
+  (if (or (= start-x end-x)
+          (= start-y end-y))
+      (trivial-ortho-line start-x start-y end-x end-y)
+      (let* ((dx (- end-x start-x))
+             (dy (- end-y start-y))
+             (nx (abs dx))
+             (ny (abs dy))
+             (sign-x (if (> dx 0) 1 -1))
+             (sign-y (if (> dy 0) 1 -1))
+             (work-x start-x)
+             (work-y start-y)
+             (drawn `((,start-x ,start-y))))
+        (loop
+          with ix = 0
+          with iy = 0
+          while (or (< ix nx) (< iy ny))
+          do (progn
+               (if (< (/ (+ 0.5 ix) nx) (/ (+ 0.5 iy) ny))
+                   (setf work-x (+ work-x sign-x)
+                         ix (1+ ix))
+                   (setf work-y (+ work-y sign-y)
+                         iy (1+ iy)))
+               (push `(,work-x ,work-y) drawn)))
+        (nreverse drawn))))
+
 (defun fill-map-from-crawler (map player)
   (with-slots (width height dungeon mobiles terrain) map
     (dotimes (x width)