Only normalize positions if actually necessary.

www/js/interpreter.ts

@@ -565,7 +565,17 @@ function danceAsLowLevelMoves(moves: Move[], startingPos: Map<DancerIdentity, Se
 }
 
 
-export const mappedDance = exampleDance.map(nameLibFigureParameters);
+export let mappedDance: Move[];
 
-export const interpretedDance = danceAsLowLevelMoves(mappedDance, handsFourImproper);
-export const interpretedAnimation: animation.Animation = animateFromLowLevelMoves(interpretedDance);
+export let interpretedDance: Map<DancerIdentity, LowLevelMove[]>;
+export let interpretedAnimation: animation.Animation;
+
+export function loadDance(dance: LibFigureDance): animation.Animation {
+  mappedDance = dance.map(nameLibFigureParameters);
+  interpretedDance = danceAsLowLevelMoves(mappedDance, handsFourImproper);
+  interpretedAnimation = animateFromLowLevelMoves(interpretedDance);
+
+  return interpretedAnimation;
+}
+
+loadDance(exampleDance);

www/js/lowLevelMove.ts

@@ -491,11 +491,17 @@ export function animateLowLevelMove(move: LowLevelMove): animation.AnimationSegm
     throw "Unsupported move in animateLowLevelMove: " + JSON.stringify(move);
   }
 
-  return [
-    animation.LinearAnimationSegment.standStill(startSetPosition),
-    ...handleMove(),
-    animation.LinearAnimationSegment.standStill(endSetPosition),
-  ];
+  const anim: animation.AnimationSegment[] = handleMove();
+
+  // Normalize start/end positions if necessary.
+  if (JSON.stringify(anim[0].startPosition) != JSON.stringify(startSetPosition)) {
+    anim.unshift(animation.LinearAnimationSegment.standStill(startSetPosition))
+  }
+  if (JSON.stringify(anim[anim.length - 1].endPosition) != JSON.stringify(endSetPosition)) {
+    anim.push(animation.LinearAnimationSegment.standStill(endSetPosition))
+  }
+
+  return anim;
 }
 
 export function animateFromLowLevelMoves(moves: Map<DancerIdentity, LowLevelMove[]>): animation.Animation {

www/js/main.ts

@@ -2,7 +2,7 @@ import * as animation from "./animation.js";
 import * as interpreter from "./interpreter.js";
 import * as renderer from "./renderer.js";
 import { DancerIdentity } from "./danceCommon.js";
-import { Move } from "./libfigureMapper.js";
+import { LibFigureDance, Move } from "./libfigureMapper.js";
 import { animateLowLevelMove, LowLevelMove } from "./lowLevelMove.js";
 
 const body = document.querySelector('body')!;
@@ -139,6 +139,32 @@ function playAnimation(bpm: number, start: number, end: number) {
   anim();
 }
 
+// Two Hearts in Time by Isaac Banner. Selected arbitrarily.
+const exampleDance: LibFigureDance = [{ "parameter_values": [true, 8], "move": "petronella" }, { "parameter_values": [true, 8], "move": "petronella" }, { "parameter_values": ["neighbors", "balance", 16], "move": "swing" }, { "parameter_values": ["ladles", true, 540, 8], "move": "allemande" }, { "parameter_values": ["partners", "none", 8], "move": "swing" }, { "parameter_values": ["gentlespoons", 360, 6], "move": "mad robin" }, { "parameter_values": [true, 270, 6], "move": "circle" }, { "parameter_values": ["partners", 4], "move": "California twirl", "progression": 1 }];
+
+const danceJsonArea = document.createElement('textarea');
+danceJsonArea.value = JSON.stringify(exampleDance, undefined, 2);
+danceJsonArea.rows = 15;
+danceJsonArea.cols = 30;
+const loadDanceButton = document.createElement('button');
+loadDanceButton.innerText = 'Load Dance';
+wrapperDiv.appendChild(document.createElement('br'));
+wrapperDiv.appendChild(danceJsonArea);
+wrapperDiv.appendChild(loadDanceButton);
+
+loadDanceButton.addEventListener('click', (ev) => {
+  const dance: LibFigureDance = JSON.parse(danceJsonArea.value);
+  r.animation = interpreter.loadDance(dance);
+  if (cancelAnim !== undefined) {
+    cancelAnimationFrame(cancelAnim);
+    playButton.innerText = 'Play';
+  }
+  beatSlider.value = '0';
+  beatDisplay.innerText = '0';
+  r.drawSetsWithTrails(0);
+  buildDebugTable();
+});
+
 function createJsonCell(content: any, rowSpan?: number, id?: DancerIdentity) {
   const cell = document.createElement('td');
   const pre = document.createElement('pre');
@@ -195,6 +221,11 @@ body.appendChild(showDebugLabel);
 const table = document.createElement('table');
 table.id = 'debug'
 
+function buildDebugTable() {
+  while (table.childNodes.length > 0) {
+    table.removeChild(table.childNodes[table.childNodes.length - 1]);
+  }
+
   const headerRow = document.createElement('tr');
   const roles = [DancerIdentity.OnesLark, DancerIdentity.OnesRobin,
   DancerIdentity.TwosLark, DancerIdentity.TwosRobin];
@@ -251,5 +282,7 @@ for (const infoForMove of byMove) {
       table.appendChild(row);
     }
   }
+}
+buildDebugTable();
 
 body.appendChild(table);