node-2d: Improve speed of root node world matrix calculation.

1 files changed, 5 insertions, 4 deletions

diff --git a/catbird/node-2d.scm b/catbird/node-2d.scm
index 47749cc..a7fcda8 100644
--- a/catbird/node-2d.scm
+++ b/catbird/node-2d.scm
@@ -152,11 +152,12 @@
 (define (refresh-world-matrix node world)
   (let ((p (parent node))
         (local (local-matrix node)))
+    ;; If the parent isn't a 2D node, then we consider this to be a
+    ;; root node, which means the world matrix is the same as the
+    ;; local matrix.
     (if (is-a? p <node-2d>)
-        (matrix4-mult! world local (world-matrix (parent node)))
-        (begin
-          (matrix4-identity! world)
-          (matrix4-mult! world world local)))
+        (matrix4-mult! world local (world-matrix p))
+        (matrix4-copy! local world))
     world))
 
 (define (refresh-inverse-world-matrix node inverse)