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diff --git a/guile/starlet/snap-transition.scm b/guile/starlet/snap-transition.scm
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+;;
+;; starlet/snap-transition.scm
+;;
+;; Copyright © 2021-2023 Thomas White <taw@bitwiz.org.uk>
+;;
+;; This file is part of Starlet.
+;;
+;; Starlet is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;
+(define-module (starlet snap-transition)
+  #:use-module (starlet cue-part)
+  #:use-module (starlet state)
+  #:use-module (starlet attributes)
+  #:export (snap))
+
+
+(define (blank-everything in-state)
+  (let ((out-state (make-empty-state)))
+    (state-for-each
+      (lambda (fix attr val)
+        (if (intensity? attr)
+          (set-in-state! out-state fix attr (lambda () 0.0))
+          (set-in-state! out-state fix attr (lambda () 'no-value))))
+      in-state)
+    out-state))
+
+
+(define (snap to-state)
+  (cue-part
+    to-state
+    (lambda (incoming-state current-state clock)
+      (let ((overlay-state (blank-everything current-state)))
+        (state-for-each
+          (lambda (fix attr val)
+            (set-in-state! overlay-state
+                           fix
+                           attr
+                           (lambda () val)))
+          incoming-state)
+        (values overlay-state 0)))))