contra-renderer/www/js/lowLevelMove.ts

import * as animation from "./animation.js";
import * as common from "./danceCommon.js";
import { DanceRole, DancerIdentity, Rotation } from "./danceCommon.js";
import { BalanceWeight, CirclePosition, CircleSide, CircleSideOrCenter, DancerDistance, Facing, HandConnection, HandTo, LongLines, PositionKind, SemanticPosition, ShortLinesPosition, StarGrip, handsInCircle } from "./interpreterCommon.js";
import { Move } from "./libfigureMapper.js";
import { DancerSetPosition, Hand, Offset, OffsetPlus, OffsetRotate, OffsetTimes, OffsetTranspose, dancerHeightOffset, dancerWidth, lineDistance, offsetZero, setDistance, setHeight, setSpacing, setWidth } from "./rendererConstants.js";


export enum SemanticAnimationKind {
  StandStill = "StandStill",

  // Long lines, balances?, slide, walk forward to new wave
  Linear = "Linear",

  // Rotate around a set: circle left/right, star
  Circle = "Circle",

  Star = "Star",

  // Walk in rectangle pattern passing by someone. Also Mad Robin and See Saw. Pousset might fit here?
  DoSiDo = "DoSiDo",

  // Also pull by.
  PassBy = "PassBy",

  // California twirl, box the gnat, etc.
  TwirlSwap = "TwirlSwap",

  // Rotate as a pair around a point. Allemande, right/left shoulder round
  RotateAround = "RotateAround",

  Swing = "Swing",

  // Walk side-by-side with both hands to same hand, optionally TwirlSwap at end.
  Promenade = "Promenade",

  CourtesyTurn = "CourtesyTurn",

  // Dancer being rolled away / spinning. Other dancer is just Linear.
  RollAway = "RollAway",
}
export type SemanticAnimation = {
  setSlideAmount?: number,
} & ({
  kind: SemanticAnimationKind.StandStill,
} | {
  kind: SemanticAnimationKind.Linear,

  // Approximate rotation. endPosition determines final orientation, generally a multiple of +/-360.
  minRotation?: number,

  handsDuring?: "Linear" | "None" | "Start" | "End";
} | {
  kind: SemanticAnimationKind.Circle,

  minRotation?: number,

  // positive is to the left.
  places: number,
} | {
  kind: SemanticAnimationKind.DoSiDo,

  minRotation?: number,

  // amount to do si do, measured in degrees clockwise (negative for counterclockwise/passing by left)
  amount: number,

  around: CircleSideOrCenter,
} | {
  kind: SemanticAnimationKind.RotateAround,

  minAmount: number,

  around: CircleSideOrCenter,

  byHand: Hand | undefined,

  // If true, move in close while rotating.
  close: boolean,
} | {
  kind: SemanticAnimationKind.Swing,

  minAmount: number,

  around: CircleSideOrCenter,

  endFacing: Facing,

  // Swings are asymmetric. This is usually but not always the dancer's role.
  swingRole: common.DanceRole,
} | {
  kind: SemanticAnimationKind.TwirlSwap,

  around: CircleSide,

  hand: Hand,
} | {
  kind: SemanticAnimationKind.PassBy,

  around: CircleSideOrCenter,

  otherPath: "Swap" | {
    start: SemanticPosition,
    end: SemanticPosition,
  }

  side: Hand,

  // If true, pull by the specified hand, if false, just pass by that side without hands.
  withHands: boolean,

  // Face the same direction the whole time or in the direction of the movement.
  facing: "Start" | "Forward",
} | {
  kind: SemanticAnimationKind.CourtesyTurn,
  clockwise?: boolean,
} | {
  kind: SemanticAnimationKind.RollAway,
} | {
  kind: SemanticAnimationKind.Promenade,

  swingRole: DanceRole,

  twirl: boolean,

  passBy: Hand,
} | {
  kind: SemanticAnimationKind.Star,

  hand: Hand,

  grip?: StarGrip,

  // Positive is to the left. Note that means this is always negative for a left hand star.
  places: number,
});


// TODO
export interface LowLevelMove {
  // for debugging messages
  remarks?: string,
  interpreterError?: string,
  // move is here for reference/debugging, shouldn't actually get used.
  move: Move,
  // for debugging, if move has been broken into multiple low-level moves, where does this one start
  startBeat: number,

  // How many beats does this take up?
  beats: number,

  // TODO decide if startPosition, endPosition, or both need to adjust for adjacent moves.
  // TODO when are hands optional?
  // Position this should start in. Previous move might not end here? Or should adjust to end here?
  startPosition: SemanticPosition,
  // Position this should end in. Next move night not star there? Or should adjust to start here?
  endPosition: SemanticPosition,

  movementPattern: SemanticAnimation,
  // TODO assertion of spin direction?
}


function CenterOfSet(setOffset?: number, lineOffset?: number): Offset {
  let position = {x: 0, y: 0};

  if (setOffset) position.y += setOffset * setDistance;
  if (lineOffset) position.x += lineOffset * lineDistance;

  return position;
}
function CenterOf(sideOrCenter: CircleSideOrCenter, setOffset?: number, lineOffset?: number): Offset {
  const setCenter = CenterOfSet(setOffset, lineOffset);

  if (sideOrCenter === "Center") return setCenter;
  const side : CircleSide = sideOrCenter;

  const xOffset = side === CircleSide.Left ? -1 : side === CircleSide.Right ? +1 : 0;
  const yOffset = side === CircleSide.Top ? -1 : side === CircleSide.Bottom ? +1 : 0;

  return { x: setCenter.x + xOffset, y: setCenter.y + yOffset };
}

function swingHandPosition(role: DancerDistance.SwingLark | DancerDistance.SwingRobin, hand: Hand): Offset {
  if (role === DancerDistance.SwingLark) {
    if (hand === Hand.Left) {
      return { x: 0, y: Math.sqrt(1 / 2) };
    }
    else {
      return { x: 0.8, y: 0.5 };
    }
  } else /* role === DancerDistance.SwingRobin */ {
    if (hand === Hand.Left) {
      return { x: -0.8, y: 0.5 };
    }
    else {
      return { x: 0, y: Math.sqrt(1 / 2) };
    };
  }
}
function swingHandPositions(role: DancerDistance.SwingLark | DancerDistance.SwingRobin): Map<Hand, Offset> {
  return new Map<Hand, Offset>([
    [Hand.Left, swingHandPosition(role, Hand.Left)],
    [Hand.Right, swingHandPosition(role, Hand.Right)],
  ]);
}

function SemanticToSetPosition(semantic: SemanticPosition): DancerSetPosition {

  let rotation: number;
  let position: Offset;
  const balanceAmount = 0.25;
  const setOffset = CenterOfSet(semantic.setOffset, semantic.lineOffset);

  switch (semantic.kind) {
    case PositionKind.Circle:
      switch (semantic.facing) {
        case Facing.CenterOfCircle:
          rotation = semantic.which.facingCenterRotation();
          break;
        case Facing.LeftInCircle:
          rotation = +90 + semantic.which.facingCenterRotation();
          break;
        case Facing.RightInCircle:
          rotation = -90 + semantic.which.facingCenterRotation();
          break;
        case Facing.Up:
          rotation = Rotation.Up;
          break;
        case Facing.Down:
          rotation = Rotation.Down;
          break;
        case Facing.Left:
          rotation = Rotation.Left;
          break;
        case Facing.Right:
          rotation = Rotation.Right;
          break;
        default:
          throw "Unexpected facing: " + semantic.facing;
      }
      let yAmount : number;
      switch (semantic.dancerDistance) {
        case DancerDistance.Normal:
        case undefined:
          yAmount = 1;
          break;
        case DancerDistance.Compact:
        case DancerDistance.SwingLark:
        case DancerDistance.SwingRobin:
          yAmount = 0.5;
          break;
        default:
          throw "Unknown DancerDistance: " + (<any>semantic).dancerDistance;
      }
      switch (semantic.which) {
        case CirclePosition.TopLeft:
          position = { x: -1, y: -yAmount };
          break;
        case CirclePosition.TopRight:
          position = { x: +1, y: -yAmount };
          break;
        case CirclePosition.BottomLeft:
          position = { x: -1, y: +yAmount };
          break;
        case CirclePosition.BottomRight:
          position = { x: +1, y: +yAmount };
          break;
        default:
          throw "Invalid circle position: " + semantic.which;
      }
      switch(semantic.longLines) {
        case LongLines.Forward:
          position.x *= 0.25;
      }
      let balanceOffset: Offset = offsetZero;
      if (semantic.balance) {
        if (semantic.facing === Facing.CenterOfCircle) {
          if (semantic.balance === BalanceWeight.Forward) {
            position = { x: position.x * (1-balanceAmount), y: position.y * (1-balanceAmount) };
          } else {
            throw "Don't know what balancing in a circle not forward means. BalanceWeight=" + semantic.balance;
          }
        } else if ((semantic.facing === Facing.Up || semantic.facing === Facing.Down)
          && (semantic.balance === BalanceWeight.Backward || semantic.balance === BalanceWeight.Forward)) {
          balanceOffset = {
            x: 0,
            y: position.y * (
              semantic.balance === BalanceWeight.Forward
                ? -balanceAmount
                : balanceAmount)
          };
        } else if ((semantic.facing === Facing.Left || semantic.facing === Facing.Right)
          && (semantic.balance === BalanceWeight.Backward || semantic.balance === BalanceWeight.Forward)) {
          balanceOffset = {
            x: (semantic.balance === BalanceWeight.Forward) === (semantic.facing === Facing.Left)
              ? -balanceAmount
              : balanceAmount,
            y: 0
          };
        } else if ((semantic.facing === Facing.Left || semantic.facing === Facing.Right)
          && (semantic.balance === BalanceWeight.Left || semantic.balance === BalanceWeight.Right)) {
          balanceOffset = {
            x: 0,
            y: (semantic.balance === BalanceWeight.Left) === (semantic.facing === Facing.Left)
              ? -balanceAmount
              : balanceAmount
          };
        } else if ((semantic.facing === Facing.Up || semantic.facing === Facing.Down)
          && (semantic.balance === BalanceWeight.Left || semantic.balance === BalanceWeight.Right)) {
          balanceOffset = {
            x: (semantic.balance === BalanceWeight.Left) === (semantic.facing === Facing.Up)
              ? -balanceAmount
              : balanceAmount,
            y: 0
          };
        }
      }
      position = OffsetPlus(position, balanceOffset, setOffset);

      const isFacingUpOrDown = semantic.facing === Facing.Up || semantic.facing === Facing.Down;
      if (semantic.dancerDistance === DancerDistance.SwingLark || semantic.dancerDistance == DancerDistance.SwingRobin) {
        if (isFacingUpOrDown == (semantic.dancerDistance === DancerDistance.SwingLark)) {
          rotation -= 45;
        } else {
          rotation += 45;
        }

        return {
          position,
          rotation,
          leftArmEnd: swingHandPosition(semantic.dancerDistance, Hand.Left),
          rightArmEnd: swingHandPosition(semantic.dancerDistance, Hand.Right),
        };
      }

      function processHandInCircle(hand: Hand, connection: HandConnection | undefined): Offset | undefined {
        // TODO Hands. Might need more info? Or need context of nearby dancer SemanticPositions?
        if (!connection) return undefined;

        const balanceHandAdjustment = OffsetRotate(balanceOffset, -rotation);
        switch (connection.to) {
          case HandTo.DancerLeft:
            return OffsetPlus({ x: -1, y: 0 }, balanceHandAdjustment);
          case HandTo.DancerRight:
            return OffsetPlus({ x: +1, y: 0 }, balanceHandAdjustment);
          case HandTo.DancerForward:
            const armLength = yAmount + (semantic.balance === BalanceWeight.Backward ? balanceAmount : 0);
            if (hand === connection.hand) {
              return { x: 0, y: +armLength/2 };
            } else {
              return { x: dancerWidth / 2 * (hand === Hand.Left ? -1 : +1), y: +armLength };
            }
          case HandTo.LeftInCircle:
          case HandTo.RightInCircle:
            const xSign = connection.to === HandTo.LeftInCircle ? -1 : +1;
            const balanceFactor = semantic.balance === BalanceWeight.Forward ? 1 - balanceAmount : 1;
            return { x: balanceFactor * xSign / Math.sqrt(2), y: balanceFactor / Math.sqrt(2) };
          case HandTo.DiagonalAcrossCircle:
            // TODO Is "diagonal" even enough information?
            return { x: -0.5, y: +0.5 }
          default:
            throw "Unkown connection: " + connection.to;
        }
      }

      return {
        position,
        rotation,
        leftArmEnd: processHandInCircle(Hand.Left, semantic.hands?.get(Hand.Left)),
        rightArmEnd: processHandInCircle(Hand.Right, semantic.hands?.get(Hand.Right)),
      };

    case PositionKind.ShortLines:
      switch (semantic.facing) {
        case Facing.Up:
          rotation = Rotation.Up;
          break;
        case Facing.Down:
          rotation = Rotation.Down;
          break;
        case Facing.Left:
          rotation = Rotation.Left;
          break;
        case Facing.Right:
          rotation = Rotation.Right;
          break;
        default:
          throw "Unexpected facing: " + semantic.facing;
      }

      switch (semantic.which) {
        case ShortLinesPosition.FarLeft:
          position = { x: -1.5, y: 0 };
          break;
        case ShortLinesPosition.MiddleLeft:
          position = { x: -0.5, y: 0 };
          break;
        case ShortLinesPosition.MiddleRight:
          position = { x: +0.5, y: 0 };
          break;
        case ShortLinesPosition.FarRight:
          position = { x: +1.5, y: 0 };
          break;
        default:
          throw "Invalid circle position: " + semantic.which;
      }
      const shortWavesBalanceAmount = 0.1;
      if (semantic.balance) {
        if ((semantic.facing === Facing.Up || semantic.facing === Facing.Down)
          && (semantic.balance === BalanceWeight.Backward || semantic.balance === BalanceWeight.Forward)) {
          position = {
            x: position.x,
            y: position.y + (
              (semantic.balance === BalanceWeight.Forward) === (semantic.facing === Facing.Up)
                ? -shortWavesBalanceAmount
                : shortWavesBalanceAmount)
          };
        } else if ((semantic.facing === Facing.Left || semantic.facing === Facing.Right)
          && (semantic.balance === BalanceWeight.Backward || semantic.balance === BalanceWeight.Forward)) {
          position = {
            x: position.x + (
              (semantic.balance === BalanceWeight.Forward) === (semantic.facing === Facing.Left)
                ? -balanceAmount
                : balanceAmount),
            y: position.y
          };
        } else if ((semantic.facing === Facing.Up || semantic.facing === Facing.Down)
          && (semantic.balance === BalanceWeight.Left || semantic.balance === BalanceWeight.Right)) {
          position = {
            x: position.x + (
              (semantic.balance === BalanceWeight.Left) === (semantic.facing === Facing.Up)
                ? -balanceAmount
                : balanceAmount),
            y: position.y
          };
        }
      }
      position.x += setOffset.x;
      position.y += setOffset.y;

      function processHandInShortLines(hand: Hand, connection: HandConnection | undefined): Offset | undefined {
        // TODO Hands. Might need more info? Or need context of nearby dancer SemanticPositions?
        if (!connection) return undefined;

        const balanceYOffset = semantic.balance === BalanceWeight.Forward ? -shortWavesBalanceAmount : semantic.balance === BalanceWeight.Backward ? shortWavesBalanceAmount : 0;
        switch (connection.to) {
          case HandTo.DancerLeft:
            return { x: -0.5, y: balanceYOffset };
          case HandTo.DancerRight:
            return { x: +0.5, y: balanceYOffset };
          case HandTo.DancerForward:
            if (hand === connection.hand) {
              return { x: 0, y: +0.5 };
            } else {
              return { x: dancerWidth / 2 * (hand === Hand.Left ? -1 : +1), y: +1 };
            }
          default:
            throw "Unkown connection: " + connection.to;
        }
      }

      return {
        position,
        rotation,
        leftArmEnd: processHandInShortLines(Hand.Left, semantic.hands?.get(Hand.Left)),
        rightArmEnd: processHandInShortLines(Hand.Right, semantic.hands?.get(Hand.Right)),
      };

    default:
      throw "Unsupported PositionKind: " + (<any>semantic).kind;
  }
}

export function animateLowLevelMove(move: LowLevelMove): animation.AnimationSegment[] {
  if (!move.movementPattern.setSlideAmount) {
    return animateLowLevelMoveWithoutSlide(move);
  }

  const withoutSlide = animateLowLevelMoveWithoutSlide({
    ...move,
    movementPattern: {
      ...move.movementPattern,
      setSlideAmount: undefined
    },
    endPosition: {
      ...move.endPosition,
      setOffset: (move.endPosition.setOffset ?? 0) - (move.movementPattern.setSlideAmount ?? 0)
    },
  });

  return [new animation.SlideAnimationSegment(
    move.beats,
    withoutSlide,
    { x: 0, y: move.movementPattern.setSlideAmount * setDistance })];
}

function animateLowLevelMoveWithoutSlide(move: LowLevelMove): animation.AnimationSegment[] {
  const startSetPosition = SemanticToSetPosition(move.startPosition);
  const endSetPosition = SemanticToSetPosition(move.endPosition);

  function handleMove(): animation.AnimationSegment[] {
    switch (move.movementPattern.kind) {
      case SemanticAnimationKind.StandStill:
        // TODO Where is the check that the current position is already move.endPosition?
        //      And that end and start position are the same... modulo hands and rotation modulus?
        return [
          animation.LinearAnimationSegment.standStill(startSetPosition, move.beats),
        ];
      case SemanticAnimationKind.Linear:
        let rotation = endSetPosition.rotation - startSetPosition.rotation;
        const minRotation = move.movementPattern.minRotation;
        try {
          rotation = common.normalizeRotation(rotation, minRotation);
        } catch {
          throw new Error("Expected zero rotation, but start and end positions at different orientations: start="
            + JSON.stringify(move.startPosition) + ", end=" + JSON.stringify(move.endPosition));
        }
        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.LinearAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: {
                ...endSetPosition,
                rotation: startSetPosition.rotation + rotation,
              }
            }),
            flags: {
              hands: (move.movementPattern.handsDuring ?? "Linear") !== "Linear",
              handsDuring: move.movementPattern.handsDuring === "Linear" ? undefined : move.movementPattern.handsDuring,
            },
            startTransitionBeats: 1,
        }),
        ];
      case SemanticAnimationKind.Circle:
        if (move.startPosition.kind !== PositionKind.Circle) {
          throw "Circle must start and end in a circle.";
        }

        const posWithHands = SemanticToSetPosition({...move.endPosition, hands: handsInCircle})
        const circleHands = new Map<Hand, Offset>([
          [Hand.Left, posWithHands.leftArmEnd!],
          [Hand.Right, posWithHands.rightArmEnd!],
        ]);

        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.RotationAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: endSetPosition,
              rotation: move.movementPattern.places * 90,
              around: {
                center: CenterOfSet(move.startPosition.setOffset, move.startPosition.lineOffset),
                width: setWidth,
                height: setHeight,
              },
              facing: animation.RotationAnimationFacing.Center,
              closer: undefined,
              hands: new Map<Hand, animation.HandAnimation>([
                [Hand.Left, { kind: "End" }],
                [Hand.Right, { kind: "End" }],
              ])
            }),
            flags: {
              hands: true,
              handsDuring: circleHands,
            },
            startTransitionBeats: 1
          }),
        ];
      case SemanticAnimationKind.DoSiDo:
        // TODO Rotation
        // TODO Parameters: rotation, amount, direction, diagonal?

        if (move.startPosition.kind !== PositionKind.Circle) {
          throw "DoSiDo must start in a circle: " + JSON.stringify(move);
        }
        const center = CenterOf(move.startPosition.which.leftRightSide(), move.startPosition.setOffset, move.startPosition.lineOffset);
        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.RotationAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: endSetPosition,
              rotation: move.movementPattern.amount,
              around: {
                center,
                width: setWidth / 3,
                height: setHeight,
              },
              facing: animation.RotationAnimationFacing.Start,
            }),
            flags: {
              rotation: true,
              hands: true,
              handsDuring: "None",
            },
            startTransitionBeats: 0,
            endTransitionBeats: 1,
          }),
        ];
      case SemanticAnimationKind.RotateAround:
        // TODO Rotation
        // TODO Parameters: rotation, amount, direction, diagonal?

        // TODO Could rotate around other things.
        const rotateCenter = CenterOf(move.movementPattern.around, move.startPosition.setOffset, move.startPosition.lineOffset);
        const hands = move.movementPattern.byHand
          ? new Map<Hand, animation.HandAnimation>([
            [move.movementPattern.byHand, { kind: "Center" }],
            [move.movementPattern.byHand.opposite(), { kind: "None" }],
          ])
          : new Map<Hand, animation.HandAnimation>([
            [Hand.Left, { kind: "None" }],
            [Hand.Right, { kind: "None" }],
          ]);
        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.RotationAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: endSetPosition,
              rotation: move.movementPattern.minAmount,
              around: {
                center: rotateCenter,
                width: 1,
                height: 1,
              },
              facing: animation.RotationAnimationFacing.Forward,
              closer: move.movementPattern.close ? {
                transitionBeats: 1,
                minDistance: 1,
              } : undefined,
              hands
            }),
            flags: {
              hands: true,
              rotation: true
            },
            startTransitionBeats: 1
          }),
        ];
      case SemanticAnimationKind.Swing:
        const rotateSwingCenter = CenterOf(move.movementPattern.around, move.startPosition.setOffset, move.startPosition.lineOffset);
        const dancerDistance = move.movementPattern.swingRole === DanceRole.Lark ? DancerDistance.SwingLark : DancerDistance.SwingRobin;

        const swingStart = SemanticToSetPosition({
          ...move.startPosition,
          dancerDistance,
          balance: undefined,
        });
        const beforeUnfold = SemanticToSetPosition({
          ...move.endPosition,
          dancerDistance,
        });
        const unfolded = SemanticToSetPosition({
          ...move.endPosition,
          dancerDistance: DancerDistance.Normal,
          hands: move.movementPattern.swingRole === DanceRole.Lark
            ? new Map<Hand, HandConnection>([[Hand.Right, {hand: Hand.Left, to: HandTo.DancerRight}]])
            : new Map<Hand, HandConnection>([[Hand.Left, {hand: Hand.Right, to: HandTo.DancerLeft}]]),
        });

        const swingBeats = move.beats - 2;
        const beatsPerRotation = 3;
        const minTurns = Math.floor(swingBeats / beatsPerRotation);
        const turns = Math.ceil(Math.abs(move.movementPattern.minAmount / 360));
        const swingMinRotation = (minTurns - turns) * (move.movementPattern.minAmount < 0 ? -360 : 360) + move.movementPattern.minAmount;

        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.RotationAnimationSegment({
              beats: swingBeats,
              startPosition: startSetPosition,
              endPosition: beforeUnfold,
              rotation: swingMinRotation,
              around: {
                center: rotateSwingCenter,
                width: 1,
                height: 1,
              },
              closer: {
                minDistance: 1,
                transitionBeats: 1,
              },
              facing: animation.RotationAnimationFacing.CenterRelative,
              centerRelativeTo: startSetPosition.rotation + ((move.startPosition.facing === Facing.Up || move.startPosition.facing === Facing.Down) === (dancerDistance === DancerDistance.SwingLark) ? -45 : +45)
            }),
            flags: {
              rotation: true,
              hands: true,
              handsDuring: swingHandPositions(dancerDistance),
            },
            startTransitionBeats: 1,
            endTransitionBeats: 0,
          }),
          new animation.LinearAnimationSegment({
            beats: 1,
            startPosition: beforeUnfold,
            endPosition: unfolded,
          }),
          new animation.LinearAnimationSegment({
            beats: 1,
            startPosition: unfolded,
            endPosition: endSetPosition,
          }),
        ];
      case SemanticAnimationKind.TwirlSwap:
        const twirlCenter =
          CenterOf(move.movementPattern.around, move.startPosition.setOffset, move.startPosition.lineOffset);
        const aroundTopOrBottom = move.movementPattern.around === CircleSide.Top || move.movementPattern.around === CircleSide.Bottom;
        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.RotationAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: {
                ...endSetPosition,
                // Make sure rotation is towards the arm being rotated around.
                rotation: move.movementPattern.hand === Hand.Left
                  ? endSetPosition.rotation < startSetPosition.rotation ? endSetPosition.rotation : endSetPosition.rotation - 360
                  : endSetPosition.rotation > startSetPosition.rotation ? endSetPosition.rotation : endSetPosition.rotation + 360
              },
              rotation: 180,
              around: {
                center: twirlCenter,
                width: aroundTopOrBottom ? setWidth : setWidth / 4,
                height: aroundTopOrBottom ? setHeight / 4 : setHeight,
              },
              facing: animation.RotationAnimationFacing.Linear,
              hands: new Map<Hand, animation.HandAnimation>([
                [move.movementPattern.hand, { kind: "Center" }],
                [move.movementPattern.hand.opposite(), { kind: "None" }],
              ])
            }),
            flags: { hands: true },
            startTransitionBeats: 0,
            endTransitionBeats: 1,
          })
        ];
      case SemanticAnimationKind.PassBy:
        const width = dancerWidth/2;
        const distanceAtMidpoint = move.movementPattern.side == Hand.Left ? +width : -width;
        // "Pull By" is just "Pass By" with hands.
        const passByHands = move.movementPattern.withHands
          ? new Map<Hand, animation.HandAnimation>([
            [move.movementPattern.side, { kind: "CenterUntilPassed" }],
            [move.movementPattern.side.opposite(), { kind: "None" }],
          ])
          : new Map<Hand, animation.HandAnimation>([
            [Hand.Left, { kind: "None" }],
            [Hand.Right, { kind: "None" }],
          ]);
        let endRotation = endSetPosition.rotation;
        const rotationAmount = endSetPosition.rotation - startSetPosition.rotation;
        if (rotationAmount !== 0) {
          if (rotationAmount >= 180 && move.movementPattern.side === Hand.Left) {
            endRotation -= 360;
          } else if (rotationAmount <= -180 && move.movementPattern.side === Hand.Right) {
            endRotation += 360;
          }
        }
        return [
          new animation.TransitionAnimationSegment({
            actualAnimation: new animation.StepWideLinearAnimationSegment({
              beats: move.beats,
              startPosition: startSetPosition,
              endPosition: { ...endSetPosition, rotation: endRotation },
              distanceAtMidpoint,
              otherPath: move.movementPattern.otherPath === "Swap" ? undefined : {
                start: SemanticToSetPosition(move.movementPattern.otherPath.start).position,
                end: SemanticToSetPosition(move.movementPattern.otherPath.end).position,
              },
              hands: passByHands,
              facing: move.movementPattern.facing,
            }),
            flags: {
              hands: true,
              rotation: true,
            },
            startTransitionBeats: 0.5,
          })
        ];
      case SemanticAnimationKind.CourtesyTurn:
        if (move.startPosition.kind !== PositionKind.Circle) {
          throw new Error("CourtesyTurn only supported on side of set.");
        }
        const courtesyTurnCenter = CenterOf(move.startPosition.which.leftRightSide(), move.startPosition.setOffset, move.startPosition.lineOffset);
        const cwCourtesyTurn: boolean = !!move.movementPattern.clockwise;
        const beingTurned = cwCourtesyTurn !== move.startPosition.which.isOnLeftLookingAcross();

        return [
          new animation.TransitionAnimationSegment({
          actualAnimation: new animation.RotationAnimationSegment({
            beats: move.beats,
            startPosition: startSetPosition,
            endPosition: endSetPosition,
            around: {
              center: courtesyTurnCenter,
              width: 1,
              height: 1,
            },
            rotation: cwCourtesyTurn ? +180 : -180,
            facing: beingTurned
              ? animation.RotationAnimationFacing.Forward
              : animation.RotationAnimationFacing.Backward,
            closer: {
              minDistance: dancerWidth,
              transitionBeats: 1,
            },
          }),
          flags: {
            rotation: true,
            hands: true,
            handsDuring: new Map<Hand, Offset>(beingTurned
              ? (cwCourtesyTurn
                ? [
                  [Hand.Left, { x: 0, y: -dancerHeightOffset * 2 }],
                  [Hand.Right, { x: dancerWidth / 2, y: 0 }],
                ]
                : [
                  [Hand.Right, { x: 0, y: -dancerHeightOffset * 2 }],
                  [Hand.Left, { x: -dancerWidth / 2, y: 0 }],
                ])
              : (cwCourtesyTurn
                ? [
                  [Hand.Left, { x: -dancerWidth, y: -dancerHeightOffset * 2 }],
                  [Hand.Right, { x: -dancerWidth / 2, y: 0 }],
                ]
                : [
                  [Hand.Right, { x: dancerWidth, y: -dancerHeightOffset * 2 }],
                  [Hand.Left, { x: dancerWidth / 2, y: 0 }],
                ]
              )),
            },
          startTransitionBeats: 1,
        })
        ];
      // TODO Unsupported moves, just doing linear for now.
      case SemanticAnimationKind.RollAway:
      case SemanticAnimationKind.Promenade:
      case SemanticAnimationKind.Star:
        return [
          new animation.LinearAnimationSegment({
            beats: move.beats,
            startPosition: startSetPosition,
            endPosition: endSetPosition,
          })
        ]
    }

    throw "Unsupported move in animateLowLevelMove: " + JSON.stringify(move);
  }

  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 {
  const res = new Map<DancerIdentity, animation.AnimationSegment[]>();
  for (const [id, moveList] of moves.entries()) {
    res.set(id, moveList.flatMap(move => animateLowLevelMove(move)))
  }
  return new animation.Animation(res);
}