benjivers/val Public Public: anyone can read this; the crew can change it.

/**

 * The renderer, run for real against a canvas that writes down what it was

 * asked to draw. No browser, but every line of the draw path is executed —

 * which is what catches a typo in a frame nobody can see from a unit test.

 *

 * This is the engine's half: walls, bodies, marks, arrivals. What a game puts

 * on the floor besides is drawn through hooks and tested with the game.

 */

import { expect, test } from "bun:test";

import { GHOST, ghosts, makePresence, shown, sighted } from "../../static/engine/presence.js";

import { drawScene, makeScene } from "../../static/engine/scene.js";

type Op = { op: string; args: unknown[]; alpha: number };

/** A canvas that records. Every call the renderer makes has to exist here. */

function fakeContext() {

  const ops: Op[] = [];

  const note =

    (op: string) =>

    (...args: unknown[]) => {

      // The opacity in force when the call was made: how faded a body

      // arriving into sight is, and how far a last-seen mark has dimmed.

      ops.push({ op, args, alpha: ctx.globalAlpha });

    };

  const ctx = {

    ops,

    fillStyle: "",

    strokeStyle: "",

    lineWidth: 1,

    font: "",

    textAlign: "left",

    globalAlpha: 1,

    clearRect: note("clearRect"),

    fillRect: note("fillRect"),

    strokeRect: note("strokeRect"),

    beginPath: note("beginPath"),

    closePath: note("closePath"),

    moveTo: note("moveTo"),

    lineTo: note("lineTo"),

    arc: note("arc"),

    ellipse: note("ellipse"),

    fill: note("fill"),

    stroke: note("stroke"),

    clip: note("clip"),

    rect: note("rect"),

    save: note("save"),

    restore: note("restore"),

    translate: note("translate"),

    rotate: note("rotate"),

    fillText: note("fillText"),

    measureText: (text: string) => ({ width: text.length * 6 }),

    createLinearGradient: () => ({ addColorStop() {} }),

  };

  return ctx;

}

// A room three tiles deep running east, with a pillar standing in it at

// column 5 — enough geometry for a body to hide behind.

const room = (col: number, row: number): boolean =>

  col < 1 || col > 12 || row < 1 || row > 3 || col === 5;

const TILE = 80;

const world = { solid: room, tile: TILE };

// What the engine's renderer needs of a snapshot: you, who you can see,

// and the shots you were let see. Nothing of the game.

const snapshot = (players: unknown[]) => ({

  me: { id: "me", x: 120, y: 200, angle: 0, alive: true, hp: 100 },

  players,

  shots: [],

});

const body = (over: Record<string, unknown> = {}) => ({

  id: "them",

  name: "Sable",

  x: 280,

  y: 200,

  angle: 3.1,

  hp: 100,

  alive: true,

  mate: false,

  ...over,

});

const view = { width: 900, height: 570, look: (p: { x: number; y: number; angle: number }) => p };

const eye = { x: 120, y: 200, angle: 0 };

test("a frame draws walls in runs: the whole width covered, far fewer fills", () => {

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([]), view);

  const rects = ctx.ops.filter((o) => o.op === "fillRect");

  // The bands are the full width; the rest are wall runs.

  const walls = rects

    .map((o) => ({ x: Number(o.args[0]), w: Number(o.args[2]) }))

    .filter((r) => r.w < view.width)

    .sort((a, b) => a.x - b.x);

  // This room is closed, so every column of the picture is wall: the runs

  // start at the left edge, meet end to end and reach the right one. That is

  // the same picture the old one-fill-a-column loop drew.

  expect(walls[0]!.x).toBe(0);

  let reach = 0;

  for (const rect of walls) {

    expect(rect.x).toBeLessThanOrEqual(reach);

    reach = Math.max(reach, rect.x + rect.w);

  }

  expect(reach).toBeGreaterThanOrEqual(view.width);

  // And it costs a fraction of the fills: one a column would be 900.

  expect(walls.length).toBeLessThan(view.width / 2);

});

test("a body in the open is drawn; the same body behind the pillar is not", () => {

  const open = fakeContext();

  drawScene(open as never, makeScene(), world, eye, snapshot([body()]), view);

  // The head is the only arc in this scene, so it stands for the body.

  expect(open.ops.some((o) => o.op === "arc")).toBe(true);

  const hidden = fakeContext();

  drawScene(hidden as never, makeScene(), world, eye, snapshot([body({ x: 700 })]), view);

  expect(hidden.ops.some((o) => o.op === "arc")).toBe(false);

});

test("a team mate gets a name tag and an enemy never does", () => {

  const mate = fakeContext();

  drawScene(mate as never, makeScene(), world, eye, snapshot([body({ mate: true })]), view);

  expect(mate.ops.some((o) => o.op === "fillText" && o.args[0] === "Sable")).toBe(true);

  const enemy = fakeContext();

  drawScene(enemy as never, makeScene(), world, eye, snapshot([body()]), view);

  expect(enemy.ops.some((o) => o.op === "fillText")).toBe(false);

});

test("the dead lie on the floor and wear no markers at all", () => {

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([body({ mate: true, alive: false, hp: 0 })]), view);

  // Flat on the ground: an ellipse, not an upright body with a head.

  expect(ctx.ops.some((o) => o.op === "ellipse")).toBe(true);

  // No name tag, and no chevron — the chevron is the only closed path here.

  expect(ctx.ops.some((o) => o.op === "fillText")).toBe(false);

  expect(ctx.ops.some((o) => o.op === "closePath")).toBe(false);

});

test("an enemy wears a chevron and a team mate does not", () => {

  const enemy = fakeContext();

  drawScene(enemy as never, makeScene(), world, eye, snapshot([body()]), view);

  expect(enemy.ops.some((o) => o.op === "closePath")).toBe(true);

  const mate = fakeContext();

  drawScene(mate as never, makeScene(), world, eye, snapshot([body({ mate: true })]), view);

  expect(mate.ops.some((o) => o.op === "closePath")).toBe(false);

  expect(mate.ops.some((o) => o.op === "fillText")).toBe(true);

});

test("a body has a hard dark edge, whichever side it is on", () => {

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([body()]), view);

  expect(ctx.ops.some((o) => o.op === "strokeRect")).toBe(true);

});

// ------------------------------------------- coming into sight, and leaving

test("a body arriving is drawn faded and small, and solid once it is in", () => {

  const edgeOf = (ctx: ReturnType<typeof fakeContext>) => ctx.ops.find((o) => o.op === "strokeRect")!;

  const arriving = fakeContext();

  drawScene(arriving as never, makeScene(), world, eye, snapshot([body()]), { ...view, shown: () => 0.4 });

  const solid = fakeContext();

  drawScene(solid as never, makeScene(), world, eye, snapshot([body()]), { ...view, shown: () => 1 });

  expect(edgeOf(arriving).alpha).toBeCloseTo(0.4, 5);

  expect(edgeOf(solid).alpha).toBe(1);

  // And smaller: it grows from its feet as it comes in.

  expect(Number(edgeOf(arriving).args[2])).toBeLessThan(Number(edgeOf(solid).args[2]));

  expect(Number(edgeOf(arriving).args[2])).toBeGreaterThan(Number(edgeOf(solid).args[2]) * 0.7);

});

test("a body the presence store has only just seen is the one being faded", () => {

  const seen = makePresence();

  const them = body();

  sighted(seen, [them], 100);

  const draw = (at: number) => {

    const ctx = fakeContext();

    drawScene(ctx as never, makeScene(), world, eye, snapshot([them]), {

      ...view,

      shown: (p: { id: string }) => shown(seen, p.id, at),

    });

    return ctx.ops.find((o) => o.op === "strokeRect")!;

  };

  expect(draw(100.03).alpha).toBeGreaterThan(0);

  expect(draw(100.03).alpha).toBeLessThan(1);

  expect(draw(100.5).alpha).toBe(1);

});

test("a last-seen mark is an outline, dimming, and never a body", () => {

  const marks = [{ id: "them", x: 280, y: 200, angle: 0, mate: false, fade: 0.6 }];

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([]), { ...view, marks });

  const edge = ctx.ops.find((o) => o.op === "strokeRect");

  expect(edge).toBeDefined();

  expect(edge!.alpha).toBeCloseTo(0.6, 5);

  // No head, no chevron, no name: a memory of a sighting, not a sighting.

  expect(ctx.ops.some((o) => o.op === "arc")).toBe(false);

  expect(ctx.ops.some((o) => o.op === "closePath")).toBe(false);

  expect(ctx.ops.some((o) => o.op === "fillText")).toBe(false);

  expect(GHOST).toBeGreaterThan(0);

});

test("a body that steps out of sight leaves the outline the store hands over", () => {

  const seen = makePresence();

  const them = body();

  sighted(seen, [them], 100); // in sight, in the open

  sighted(seen, [], 100.1); // and gone behind the corner

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([]), {

    ...view,

    marks: ghosts(seen, 100.1),

  });

  // Nobody is in the snapshot at all, and there is still something there.

  const edge = ctx.ops.find((o) => o.op === "strokeRect");

  expect(edge).toBeDefined();

  expect(edge!.alpha).toBeCloseTo(1, 2);

  // A second later the store hands over nothing, and nothing is drawn.

  const after = fakeContext();

  drawScene(after as never, makeScene(), world, eye, snapshot([]), {

    ...view,

    marks: ghosts(seen, 100.1 + GHOST),

  });

  expect(after.ops.some((o) => o.op === "strokeRect")).toBe(false);

});

test("a mark where the wall now stands between you and it is not drawn", () => {

  const marks = [{ id: "them", x: 700, y: 200, angle: 0, mate: false, fade: 1 }];

  const ctx = fakeContext();

  drawScene(ctx as never, makeScene(), world, eye, snapshot([]), { ...view, marks });

  expect(ctx.ops.some((o) => o.op === "strokeRect")).toBe(false);

});