miaoda-game-path-core

Use this package for scripted continuous movement along waypoints, Catmull-Rom splines, or cubic Bezier curves. It bakes curve length for approximately constant-speed travel and provides tangent-facing rotation, loop/ping-pong modes, and optional sine sway.

This is path following, not pathfinding. Use grid-core to find a route around obstacles, shooter-core for free-moving bullets, and combat2d-core for hits.

Install and follow a path

pnpm add miaoda-game-path-core

import { BakedPath, PathFollower, SplinePath } from 'miaoda-game-path-core';

const path = new SplinePath([
  { x: 900, y: 700 },
  { x: 500, y: 620 },
  { x: 220, y: 520 },
  { x: 480, y: 420 },
]);
const follower = new PathFollower(new BakedPath(path), {
  speed: 260,
  mode: 'clamp',
  sway: { amplitude: 18, frequency: 1.2 },
});

const sample = follower.tick(dtSeconds);
moveActor(sample.pos.x, sample.pos.y);
faceActor(sample.angleDeg);
if (sample.done) beginCombatAI();

speed is world units per second and tick receives seconds. Angles are degrees with 0 along +X; the renderer decides whether increasing Y appears up or down.

Choose path geometry

| Path | Use it for | | --- | --- | | PolylinePath | Exact straight segments and hard waypoint corners | | SplinePath | Smooth curves that pass through authored waypoints | | BezierPath | Explicit cubic handles for loops, hairpins, and controlled S-curves |

Raw curve parameter t is not proportional to distance. Wrap geometry in BakedPath and query by distance to avoid actors slowing on bends and accelerating on straights. Increase samplesPerSegment for tighter curves; rebuild when geometry changes.

Follower behavior

• clamp stops at the end and reports done.
• loop wraps to the start.
• pingpong reflects at both ends.
• sway adds perpendicular sine movement without changing the reported tangent heading.

Use seek to jump to a distance and setSpeed to change travel speed. The core returns desired transforms only; rendering, collision, pausing, and handing control to another movement system remain game-owned.