Kinematic Chain

A kinematic chain is composed of rigid line segments.
Each segment is represented using two vectors: base and span.

	base ----------> tip
	        span

The segment's tip is the sum of its base and span.

Move segment tip to new position:
segment.moveTipTo(position: Vec2)

	// rotate span
	const difference = position.clone().subtract(this.base);
	this.span.copy(difference.normalize().multiply(this.span.length()));
	// move segment
	this.base.copy(position).subtract(this.span);

Move entire chain to new position:
chain.moveTipTo(position: Vec2)

	for (let i = this.segments.length - 1; i >= 0; i--) {
		const segment = this.segments[i]!;
		segment.moveTipTo(position);
		position = segment.base;
	}

Anchor chain at a fixed position:
chain.anchorAt(position: Vec2)

	const displacement = this.segments[0]!.base.clone().subtract(position);
	for (const segment of this.segments) segment.base.subtract(displacement);

Kinematic Chain

See Also: