Play animation can blend into the new animation over a number of frames (#106)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/core/graph/nodes/action/animationNodes.ts

@@ -1,7 +1,7 @@
 import { pauseAnimation, playAnimation, stopAnimation } from '../../../model/animation';
 import type { NodeDef, PortDef } from '../../NodeRegistry';
-import { asEntity, asString } from '../../values';
-import { exec, obj } from '../shared';
+import { asEntity, asNumber, asString } from '../../values';
+import { exec, num, obj, withDefault } from '../shared';
 
 /**
  * The `animation` input of the three animation nodes; unconnected it shows the animation picker, the
@@ -21,14 +21,15 @@ export const PlayAnimation: NodeDef = {
   description:
     'Plays an animation on an object: its rows reach the object and what is placed inside it, so every ' +
     'instance plays on its own. A paused one runs on from where it stands; one already running keeps its ' +
-    'frame but wins again over the others on the object.',
-  inputs: [exec(), obj('object'), animationPort()],
+    'frame but wins again over the others on the object. Blend fades numbers and colours over that many ' +
+    'of its frames from what they held when it took over; everything else switches at once.',
+  inputs: [exec(), obj('object'), animationPort(), withDefault(num('blend', 'blend (frames)'), 0)],
   outputs: [exec()],
   params: [],
   run: (_ctx, inputs) => {
     const target = asEntity(inputs.object);
     const animation = asString(inputs.animation);
-    if (target && animation) playAnimation(target, animation);
+    if (target && animation) playAnimation(target, animation, Math.max(0, asNumber(inputs.blend)));
     return { next: 'exec' };
   },
 };