node-2d: Add world->local method.

1 files changed, 13 insertions, 9 deletions

diff --git a/catbird/node-2d.scm b/catbird/node-2d.scm
index 868604a..79a0dba 100644
--- a/catbird/node-2d.scm
+++ b/catbird/node-2d.scm
@@ -102,6 +102,7 @@
             teleport
             world-bounding-box
             world-matrix
+            world->local
 
             <sprite>
             texture
@@ -602,19 +603,22 @@
 (define-method (follow-bezier-path (node <node-2d>) path duration)
   (follow-bezier-path node path duration #t))
 
+(define-method (world->local (node <node-2d>) p)
+  (matrix4-transform-vec2 (inverse-world-matrix node) p))
+
 (define-method (pick (node <node-2d>) p)
   (let loop ((kids (reverse (children node))))
     (match kids
       (()
-       (let* ((m (inverse-world-matrix node))
-              (x (vec2-x p))
-              (y (vec2-y p))
-              (tx (matrix4-transform-x m x y))
-              (ty (matrix4-transform-y m x y)))
-         (and (>= tx 0.0)
-              (< tx (width node))
-              (>= ty 0.0)
-              (< ty (height node))
+       ;; Multiply the cursor position by the inverse world matrix to
+       ;; translate world coordinates into node-local coordinates.
+       (let* ((p* (world->local node p))
+              (x (vec2-x p*))
+              (y (vec2-y p*)))
+         (and (>= x 0.0)
+              (< x (width node))
+              (>= y 0.0)
+              (< y (height node))
               node)))
       ((child . rest)
        (let ((o (origin node)))