node-2d: Short circuit move-by if dx/dy are both 0.

1 files changed, 15 insertions, 11 deletions

diff --git a/catbird/node-2d.scm b/catbird/node-2d.scm
index 41f82db..34a7417 100644
--- a/catbird/node-2d.scm
+++ b/catbird/node-2d.scm
@@ -487,19 +487,23 @@
   (move-to node x y duration smoothstep))
 
 (define-method (move-by (node <node-2d>) dx dy)
-  (let ((p (position node)))
-    (move-to node (+ (vec2-x p) dx) (+ (vec2-y p) dy))))
+  ;; No-op if the node wouldn't be moved at all.
+  (unless (and (= dx 0.0) (= dy 0.0))
+    (let ((p (position node)))
+      (move-to node (+ (vec2-x p) dx) (+ (vec2-y p) dy)))))
 
 (define-method (move-by (node <node-2d>) dx dy duration ease)
-  (let* ((p (position node))
-         (start-x (vec2-x p))
-         (start-y (vec2-y p)))
-    (tween duration 0.0 1.0
-           (lambda (n)
-             (move-to node
-                      (+ start-x (* dx n))
-                      (+ start-y (* dy n))))
-           #:ease ease)))
+  ;; No-op if the node wouldn't be moved at all.
+  (unless (and (= dx 0.0) (= dy 0.0))
+    (let* ((p (position node))
+           (start-x (vec2-x p))
+           (start-y (vec2-y p)))
+      (tween duration 0.0 1.0
+             (lambda (n)
+               (move-to node
+                        (+ start-x (* dx n))
+                        (+ start-y (* dy n))))
+             #:ease ease))))
 
 (define-method (move-by (node <node-2d>) dx dy duration)
   (move-by node dx dy duration smoothstep))