galaxy-game/ui/frontend/tests/fog-paint-ops.test.ts

// Phase 29 unit coverage for the Phase 29 fog overlay's layered
// overpaint logic. `fogPaintOps` lives in `src/map/render.ts` next
// to its sole consumer (`RendererHandle.setVisibilityFog`) — the
// renderer dispatches each op straight onto a Pixi `Graphics`, so
// the unit test exercises the public ordering contract: a single
// fog-coloured rectangle followed by one background-coloured
// circle per visibility entry. The natural rendering order unions
// overlapping circles for free, replacing the earlier `cut()`
// implementation that produced disconnected arc segments.

import { describe, expect, test } from "vitest";

import { FOG_COLOR, fogPaintOps } from "../src/map/render";

const BG_COLOR = 0x0a0e1a;
const WORLD = { width: 1000, height: 800 };

describe("fogPaintOps", () => {
	test("empty input returns no ops", () => {
		expect(fogPaintOps(WORLD, [], FOG_COLOR, BG_COLOR)).toEqual([]);
	});

	test("single circle emits fog rect + one bg circle in that order", () => {
		const ops = fogPaintOps(
			WORLD,
			[{ x: 100, y: 200, radius: 50 }],
			FOG_COLOR,
			BG_COLOR,
		);
		expect(ops).toEqual([
			{
				kind: "fillRect",
				x: 0,
				y: 0,
				width: 1000,
				height: 800,
				color: FOG_COLOR,
				alpha: 1,
			},
			{
				kind: "fillCircle",
				x: 100,
				y: 200,
				radius: 50,
				color: BG_COLOR,
				alpha: 1,
			},
		]);
	});

	test("multiple circles produce one fog rect followed by N bg circles", () => {
		const ops = fogPaintOps(
			WORLD,
			[
				{ x: 100, y: 100, radius: 50 },
				{ x: 300, y: 200, radius: 80 },
				{ x: 500, y: 600, radius: 30 },
			],
			FOG_COLOR,
			BG_COLOR,
		);
		expect(ops.length).toBe(4);
		expect(ops[0].kind).toBe("fillRect");
		for (let i = 1; i < ops.length; i++) {
			expect(ops[i].kind).toBe("fillCircle");
			// Background-coloured circles paint on top of the fog rect.
			const op = ops[i];
			if (op.kind === "fillCircle") {
				expect(op.color).toBe(BG_COLOR);
				expect(op.alpha).toBe(1);
			}
		}
	});

	test("overlapping circles are emitted independently — the rendering order unions them", () => {
		// Two overlapping circles around adjacent LOCAL planets — the
		// op list keeps both circles. The renderer relies on the
		// overpaint to merge them visually; `cut()` (the previous
		// implementation) miscomputed the union.
		const ops = fogPaintOps(
			WORLD,
			[
				{ x: 200, y: 200, radius: 100 },
				{ x: 250, y: 200, radius: 100 },
			],
			FOG_COLOR,
			BG_COLOR,
		);
		expect(ops.length).toBe(3);
		expect(ops[1]).toMatchObject({ x: 200, y: 200, radius: 100 });
		expect(ops[2]).toMatchObject({ x: 250, y: 200, radius: 100 });
	});

	test("the fog rect always covers the full world rectangle", () => {
		const ops = fogPaintOps(
			{ width: 3200, height: 1600 },
			[{ x: 0, y: 0, radius: 10 }],
			FOG_COLOR,
			BG_COLOR,
		);
		expect(ops[0]).toEqual({
			kind: "fillRect",
			x: 0,
			y: 0,
			width: 3200,
			height: 1600,
			color: FOG_COLOR,
			alpha: 1,
		});
	});

	test("zero or negative world dimensions return no ops", () => {
		expect(
			fogPaintOps(
				{ width: 0, height: 800 },
				[{ x: 0, y: 0, radius: 10 }],
				FOG_COLOR,
				BG_COLOR,
			),
		).toEqual([]);
		expect(
			fogPaintOps(
				{ width: 1000, height: -1 },
				[{ x: 0, y: 0, radius: 10 }],
				FOG_COLOR,
				BG_COLOR,
			),
		).toEqual([]);
	});
});