Function computeParallaxPos

packages/melonjs/tests/tmxutils.spec.js:607–618

(
			offset,
			ratio,
			camPos,
			anchorPoint,
			boundsW,
			viewportW,
		)

	describe("parallax origin offset baking", () => {
		// Helper: compute parallax position the way ImageLayer.draw does
		function computeParallaxPos(
			offset,
			ratio,
			camPos,
			anchorPoint,
			boundsW,
			viewportW,
		) {
			const ax = anchorPoint;
			const rx = ratio;
			return ax * (rx - 1) * (boundsW - viewportW) + offset - rx * camPos;
		}

		it("baked offset matches explicit parallax origin (ax=0, ratio=0.5)", () => {
			const layerOffset = 100;