boundingbox + draw player

src/App.tsx

@@ -23,6 +23,10 @@ export const App = () => {
             className="tf"
           >
             simponic
+          </a>{" "}
+          | inspired by{" "}
+          <a href="https://hempuli.com/baba/" target="_blank" className="tf">
+            baba is you
           </a>
         </span>
       </div>

src/components/GameCanvas.tsx

@@ -1,4 +1,5 @@
-import { useRef } from "react";
+import { useState, useEffect, useRef } from "react";
+import { TheAbstractionEngine, Game } from "../engine";
 
 export interface GameCanvasProps {
   width: number;
@@ -7,6 +8,25 @@ export interface GameCanvasProps {
 
 export const GameCanvas = ({ width, height }: GameCanvasProps) => {
   const canvasRef = useRef<HTMLCanvasElement>(null);
+  const [_game, setGame] = useState<TheAbstractionEngine>();
+
+  useEffect(() => {
+    if (canvasRef.current) {
+      const canvas = canvasRef.current;
+      const ctx = canvas.getContext("2d");
+      if (ctx) {
+        const game = new Game();
+        const theAbstractionEngine = new TheAbstractionEngine(game, ctx);
+
+        theAbstractionEngine.init().then(() => {
+          theAbstractionEngine.play();
+          setGame(theAbstractionEngine);
+        });
+
+        return () => theAbstractionEngine.stop();
+      }
+    }
+  }, [canvasRef]);
 
   return (
     <div className="centered-game">

src/engine/Game.ts

@@ -0,0 +1,90 @@
+import { Entity } from "./entities";
+import { System } from "./systems";
+
+export class Game {
+  private systemOrder: string[];
+
+  private running: boolean;
+  private lastTimeStamp: number;
+
+  public entities: Map<string, Entity>;
+  public systems: Map<string, System>;
+  public componentEntities: Map<string, Set<string>>;
+
+  constructor() {
+    this.lastTimeStamp = performance.now();
+    this.running = false;
+    this.systemOrder = [];
+    this.systems = new Map();
+    this.entities = new Map();
+    this.componentEntities = new Map();
+  }
+
+  public start() {
+    this.lastTimeStamp = performance.now();
+    this.running = true;
+  }
+
+  public addEntity(entity: Entity) {
+    this.entities.set(entity.id, entity);
+  }
+
+  public getEntity(id: string): Entity | undefined {
+    return this.entities.get(id);
+  }
+
+  public removeEntity(id: string) {
+    this.entities.delete(id);
+  }
+
+  public forEachEntityWithComponent(
+    componentName: string,
+    callback: (entity: Entity) => void,
+  ) {
+    this.componentEntities.get(componentName)?.forEach((entityId) => {
+      const entity = this.getEntity(entityId);
+      if (!entity) return;
+
+      callback(entity);
+    });
+  }
+
+  public addSystem(system: System) {
+    if (!this.systemOrder.includes(system.name)) {
+      this.systemOrder.push(system.name);
+    }
+    this.systems.set(system.name, system);
+  }
+
+  public getSystem<T>(name: string): T {
+    return this.systems.get(name) as unknown as T;
+  }
+
+  public doGameLoop(timeStamp: number) {
+    if (!this.running) {
+      return;
+    }
+
+    const dt = timeStamp - this.lastTimeStamp;
+    this.lastTimeStamp = timeStamp;
+
+    // rebuild the Component -> { Entity } map
+    this.componentEntities.clear();
+    this.entities.forEach((entity) =>
+      entity.getComponents().forEach((component) => {
+        if (!this.componentEntities.has(component.name)) {
+          this.componentEntities.set(
+            component.name,
+            new Set<string>([entity.id]),
+          );
+          return;
+        }
+        this.componentEntities.get(component.name)?.add(entity.id);
+      }),
+    );
+
+    this.systemOrder.forEach((systemName) => {
+      this.systems.get(systemName)?.update(dt, this);
+    });
+  }
+}

src/engine/TheAbstractionEngine.ts

@@ -0,0 +1,42 @@
+import { Game } from ".";
+import { loadAssets } from "./config";
+import { Player } from "./entities";
+import { Render } from "./systems";
+
+export class TheAbstractionEngine {
+  private game: Game;
+  private ctx: CanvasRenderingContext2D;
+  private animationFrameId: number | null;
+
+  constructor(game: Game, ctx: CanvasRenderingContext2D) {
+    this.game = game;
+    this.ctx = ctx;
+    this.animationFrameId = null;
+  }
+
+  public async init() {
+    await loadAssets();
+
+    [new Render(this.ctx)].forEach((system) => this.game.addSystem(system));
+
+    const player = new Player();
+    this.game.addEntity(player);
+  }
+
+  public play() {
+    this.game.start();
+
+    const loop = (timestamp: number) => {
+      this.game.doGameLoop(timestamp);
+      this.animationFrameId = requestAnimationFrame(loop); // tail call recursion! /s
+    };
+    this.animationFrameId = requestAnimationFrame(loop);
+  }
+
+  public stop() {
+    if (this.animationFrameId) {
+      cancelAnimationFrame(this.animationFrameId);
+      this.animationFrameId = null;
+    }
+  }
+}

src/engine/components/BoundingBox.ts

@@ -0,0 +1,122 @@
+import { Component, ComponentNames } from ".";
+import type { Coord2D, Dimension2D } from "../interfaces";
+import { dotProduct, rotateVector } from "../utils";
+
+export class BoundingBox extends Component {
+  public center: Coord2D;
+  public dimension: Dimension2D;
+  public rotation: number;
+
+  constructor(center: Coord2D, dimension: Dimension2D, rotation?: number) {
+    super(ComponentNames.BoundingBox);
+
+    this.center = center;
+    this.dimension = dimension;
+    this.rotation = rotation ?? 0;
+  }
+
+  public isCollidingWith(box: BoundingBox): boolean {
+    // optimization; when neither rotates just check if they overlap
+    if (this.rotation == 0 && box.rotation == 0) {
+      const thisTopLeft = this.getTopLeft();
+      const thisBottomRight = this.getBottomRight();
+
+      const thatTopLeft = box.getTopLeft();
+      const thatBottomRight = box.getBottomRight();
+
+      if (
+        thisBottomRight.x <= thatTopLeft.x ||
+        thisTopLeft.x >= thatBottomRight.x ||
+        thisBottomRight.y <= thatTopLeft.y ||
+        thisTopLeft.y >= thatBottomRight.y
+      ) {
+        return false;
+      }
+
+      return true;
+    }
+
+    // https://en.wikipedia.org/wiki/Hyperplane_separation_theorem
+    const boxes = [this.getVertices(), box.getVertices()];
+    for (const poly of boxes) {
+      for (let i = 0; i < poly.length; i++) {
+        const [A, B] = [poly[i], poly[(i + 1) % poly.length]];
+        const normal: Coord2D = { x: B.y - A.y, y: A.x - B.x };
+
+        const [[minThis, maxThis], [minBox, maxBox]] = boxes.map((box) =>
+          box.reduce(
+            ([min, max], vertex) => {
+              const projection = dotProduct(normal, vertex);
+              return [Math.min(min, projection), Math.max(max, projection)];
+            },
+            [Infinity, -Infinity],
+          ),
+        );
+
+        if (maxThis < minBox || maxBox < minThis) return false;
+      }
+    }
+
+    return true;
+  }
+
+  public getVertices(): Coord2D[] {
+    return [
+      { x: -this.dimension.width / 2, y: -this.dimension.height / 2 },
+      { x: -this.dimension.width / 2, y: this.dimension.height / 2 },
+      { x: this.dimension.width / 2, y: this.dimension.height / 2 },
+      { x: this.dimension.width / 2, y: -this.dimension.height / 2 },
+    ]
+      .map((vertex) => rotateVector(vertex, this.rotation)) // rotate
+      .map((vertex) => {
+        // translate
+        return {
+          x: vertex.x + this.center.x,
+          y: vertex.y + this.center.y,
+        };
+      });
+  }
+
+  public getRotationInPiOfUnitCircle(): number {
+    let rads = this.rotation * (Math.PI / 180);
+    if (rads >= Math.PI) {
+      // Physics system guarantees rotation \in [0, 360)
+      rads -= Math.PI;
+    }
+    return rads;
+  }
+
+  public getOutscribedBoxDims(): Dimension2D {
+    let rads = this.getRotationInPiOfUnitCircle();
+    const { width, height } = this.dimension;
+
+    if (rads == 0) return this.dimension;
+
+    if (rads <= Math.PI / 2) {
+      return {
+        width: Math.abs(height * Math.sin(rads) + width * Math.cos(rads)),
+        height: Math.abs(width * Math.sin(rads) + height * Math.cos(rads)),
+      };
+    }
+
+    rads -= Math.PI / 2;
+    return {
+      width: Math.abs(height * Math.cos(rads) + width * Math.sin(rads)),
+      height: Math.abs(width * Math.cos(rads) + height * Math.sin(rads)),
+    };
+  }
+
+  public getTopLeft(): Coord2D {
+    return {
+      x: this.center.x - this.dimension.width / 2,
+      y: this.center.y - this.dimension.height / 2,
+    };
+  }
+
+  public getBottomRight(): Coord2D {
+    return {
+      x: this.center.x + this.dimension.width / 2,
+      y: this.center.y + this.dimension.height / 2,
+    };
+  }
+}

src/engine/components/ComponentNames.ts

@@ -1,3 +1,6 @@
 export namespace ComponentNames {
   export const Sprite = "Sprite";
+  export const FacingDirection = "FacingDirection";
+  export const GridPosition = "GridPosition";
+  export const BoundingBox = "BoundingBox";
 }

src/engine/components/FacingDirection.ts

@@ -0,0 +1,12 @@
+import { Component, ComponentNames, Sprite } from ".";
+import { type Direction } from "../interfaces";
+
+export class FacingDirection extends Component {
+  public readonly directionSprites: Map<Direction, Sprite>;
+
+  constructor() {
+    super(ComponentNames.FacingDirection);
+
+    this.directionSprites = new Map<Direction, Sprite>();
+  }
+}

src/engine/components/GridPosition.ts

@@ -0,0 +1,13 @@
+import { Component, ComponentNames } from ".";
+
+export class GridPosition extends Component {
+  public x: number;
+  public y: number;
+
+  constructor(x: number, y: number) {
+    super(ComponentNames.GridPosition);
+
+    this.x = x;
+    this.y = y;
+  }
+}

src/engine/components/Sprite.ts

@@ -0,0 +1,96 @@
+import { Component, ComponentNames } from ".";
+import type { Dimension2D, DrawArgs, Coord2D } from "../interfaces";
+
+export class Sprite extends Component {
+  private sheet: HTMLImageElement;
+
+  private spriteImgPos: Coord2D;
+  private spriteImgDimensions: Dimension2D;
+
+  private msPerFrame: number;
+  private msSinceLastFrame: number;
+  private currentFrame: number;
+  private numFrames: number;
+
+  constructor(
+    sheet: HTMLImageElement,
+    spriteImgPos: Coord2D,
+    spriteImgDimensions: Dimension2D,
+    msPerFrame: number,
+    numFrames: number,
+  ) {
+    super(ComponentNames.Sprite);
+
+    this.sheet = sheet;
+    this.spriteImgPos = spriteImgPos;
+    this.spriteImgDimensions = spriteImgDimensions;
+    this.msPerFrame = msPerFrame;
+    this.numFrames = numFrames;
+
+    this.msSinceLastFrame = 0;
+    this.currentFrame = 0;
+  }
+
+  public update(dt: number) {
+    this.msSinceLastFrame += dt;
+    if (this.msSinceLastFrame >= this.msPerFrame) {
+      this.currentFrame = (this.currentFrame + 1) % this.numFrames;
+      this.msSinceLastFrame = 0;
+    }
+  }
+
+  public draw(ctx: CanvasRenderingContext2D, drawArgs: DrawArgs) {
+    const { center, rotation, tint, opacity } = drawArgs;
+
+    ctx.save();
+    ctx.translate(center.x, center.y);
+    if (rotation != undefined && rotation != 0) {
+      ctx.rotate(rotation * (Math.PI / 180));
+    }
+    ctx.translate(-center.x, -center.y);
+
+    if (opacity) {
+      ctx.globalAlpha = opacity;
+    }
+
+    ctx.drawImage(
+      this.sheet,
+      ...this.getSpriteArgs(),
+      ...this.getDrawArgs(drawArgs),
+    );
+
+    if (tint) {
+      ctx.globalAlpha = 0.5;
+      ctx.globalCompositeOperation = "source-atop";
+      ctx.fillStyle = tint;
+      ctx.fillRect(...this.getDrawArgs(drawArgs));
+    }
+
+    ctx.restore();
+  }
+
+  private getSpriteArgs(): [sx: number, sy: number, sw: number, sh: number] {
+    return [
+      this.spriteImgPos.x + this.currentFrame * this.spriteImgDimensions.width,
+      this.spriteImgPos.y,
+      this.spriteImgDimensions.width,
+      this.spriteImgDimensions.height,
+    ];
+  }
+
+  private getDrawArgs({
+    center,
+    dimension,
+  }: DrawArgs): [dx: number, dy: number, dw: number, dh: number] {
+    return [
+      center.x - dimension.width / 2,
+      center.y - dimension.height / 2,
+      dimension.width,
+      dimension.height,
+    ];
+  }
+
+  public getSpriteDimensions() {
+    return this.spriteImgDimensions;
+  }
+}

src/engine/components/index.ts

@@ -1,2 +1,6 @@
 export * from "./Component";
 export * from "./ComponentNames";
+export * from "./Sprite";
+export * from "./FacingDirection";
+export * from "./GridPosition";
+export * from "./BoundingBox";

src/engine/config/assets.ts

@@ -0,0 +1,42 @@
+import type { SpriteSpec } from "./sprites";
+import { SPRITE_SPECS } from "./sprites";
+
+export const IMAGES = new Map<string, HTMLImageElement>();
+
+export const loadSpritesIntoImageElements = (
+  spriteSpecs: Partial<SpriteSpec>[],
+): Promise<void>[] => {
+  const spritePromises: Promise<void>[] = [];
+
+  for (const spriteSpec of spriteSpecs) {
+    if (spriteSpec.sheet) {
+      const img = new Image();
+      img.src = spriteSpec.sheet;
+      IMAGES.set(spriteSpec.sheet, img);
+
+      spritePromises.push(
+        new Promise((resolve) => {
+          img.onload = () => resolve();
+        }),
+      );
+    }
+
+    if (spriteSpec.states) {
+      spritePromises.push(
+        ...loadSpritesIntoImageElements(Array.from(spriteSpec.states.values())),
+      );
+    }
+  }
+
+  return spritePromises;
+};
+
+export const loadAssets = () =>
+  Promise.all([
+    ...loadSpritesIntoImageElements(
+      Array.from(SPRITE_SPECS.keys()).map(
+        (key) => SPRITE_SPECS.get(key) as SpriteSpec,
+      ),
+    ),
+    // TODO: Sound
+  ]);

src/engine/config/constants.ts

@@ -0,0 +1,7 @@
+export namespace Miscellaneous {
+  export const WIDTH = 800;
+  export const HEIGHT = 800;
+
+  export const DEFAULT_GRID_WIDTH = 30;
+  export const DEFAULT_GRID_HEIGHT = 30;
+}

src/engine/config/index.ts

@@ -0,0 +1,3 @@
+export * from "./constants";
+export * from "./assets";
+export * from "./sprites";

src/engine/config/sprites.ts

@@ -0,0 +1,39 @@
+import { Direction } from "../interfaces/Direction";
+
+export enum Sprites {
+  PLAYER,
+}
+
+export interface SpriteSpec {
+  sheet: string;
+  width: number;
+  height: number;
+  frames: number;
+  msPerFrame: number;
+  states?: Map<string | number, Partial<SpriteSpec>>;
+}
+
+export const SPRITE_SPECS: Map<Sprites, Partial<SpriteSpec>> = new Map<
+  Sprites,
+  SpriteSpec
+>();
+
+const playerSpriteSpec = {
+  msPerFrame: 200,
+  width: 64,
+  height: 64,
+  frames: 3,
+  states: new Map<string, Partial<SpriteSpec>>(),
+};
+playerSpriteSpec.states.set(Direction.NONE, {
+  sheet: "/assets/lambda/neutral.png",
+});
+[Direction.LEFT, Direction.RIGHT, Direction.UP, Direction.DOWN].forEach(
+  (direction) => {
+    playerSpriteSpec.states.set(direction, {
+      sheet: `/assets/lambda/${direction.toLowerCase()}.png`,
+    });
+  },
+);
+
+SPRITE_SPECS.set(Sprites.PLAYER, playerSpriteSpec);

src/engine/entities/Entity.ts

@@ -1,13 +1,13 @@
 import { type Component } from "../components";
 
-const randomId = () => (Math.random() * 1_000_000_000).toString();
-
 export abstract class Entity {
+  static Id = 0;
+
   public id: string;
   public components: Map<string, Component>;
   public name: string;
 
-  constructor(name: string, id: string = randomId()) {
+  constructor(name: string, id: string = (Entity.Id++).toString()) {
     this.name = name;
     this.id = id;
     this.components = new Map();

src/engine/entities/EntityNames.ts

@@ -1,5 +1,3 @@
 export namespace EntityNames {
   export const Player = "Player";
-  export const Wall = "Wall";
-  export const Ball = "Ball";
 }

src/engine/entities/Player.ts

@@ -0,0 +1,58 @@
+import { Entity, EntityNames } from ".";
+import { IMAGES, SPRITE_SPECS, Sprites, type SpriteSpec } from "../config";
+import {
+  FacingDirection,
+  Sprite,
+  GridPosition,
+  BoundingBox,
+} from "../components";
+import { Direction } from "../interfaces/";
+
+export class Player extends Entity {
+  private static spriteSpec: SpriteSpec = SPRITE_SPECS.get(
+    Sprites.PLAYER,
+  ) as SpriteSpec;
+
+  constructor() {
+    super(EntityNames.Player);
+
+    this.addComponent(
+      new BoundingBox(
+        {
+          x: 0,
+          y: 0,
+        },
+        { width: Player.spriteSpec.width, height: Player.spriteSpec.height },
+        0,
+      ),
+    );
+
+    this.addComponent(new GridPosition(0, 0));
+    this.addFacingDirectionComponents();
+  }
+
+  private addFacingDirectionComponents() {
+    const facingDirectionComponent = new FacingDirection();
+    [
+      Direction.NONE,
+      Direction.LEFT,
+      Direction.RIGHT,
+      Direction.UP,
+      Direction.DOWN,
+    ].forEach((direction) => {
+      const sprite = new Sprite(
+        IMAGES.get(Player.spriteSpec.states!.get(direction)!.sheet!)!,
+        { x: 0, y: 0 },
+        { width: Player.spriteSpec.width, height: Player.spriteSpec.height },
+        Player.spriteSpec.msPerFrame,
+        Player.spriteSpec.frames,
+      );
+      facingDirectionComponent.directionSprites.set(direction, sprite);
+    });
+
+    this.addComponent(facingDirectionComponent);
+    this.addComponent(
+      facingDirectionComponent.directionSprites.get(Direction.NONE)!,
+    ); // face no direction by default
+  }
+}

src/engine/entities/index.ts

@@ -1,2 +1,3 @@
 export * from "./Entity";
 export * from "./EntityNames";
+export * from "./Player";

src/engine/index.ts

@@ -1,90 +1,2 @@
-import { Entity } from "./entities";
+export * from "./Game";
-import { System } from "./systems";
+export * from "./TheAbstractionEngine";
-
-export class Game {
-  private systemOrder: string[];
-
-  private running: boolean;
-  private lastTimeStamp: number;
-
-  public entities: Map<string, Entity>;
-  public systems: Map<string, System>;
-  public componentEntities: Map<string, Set<string>>;
-
-  constructor() {
-    this.lastTimeStamp = performance.now();
-    this.running = false;
-    this.systemOrder = [];
-    this.systems = new Map();
-    this.entities = new Map();
-    this.componentEntities = new Map();
-  }
-
-  public start() {
-    this.lastTimeStamp = performance.now();
-    this.running = true;
-  }
-
-  public addEntity(entity: Entity) {
-    this.entities.set(entity.id, entity);
-  }
-
-  public getEntity(id: string): Entity | undefined {
-    return this.entities.get(id);
-  }
-
-  public removeEntity(id: string) {
-    this.entities.delete(id);
-  }
-
-  public forEachEntityWithComponent(
-    componentName: string,
-    callback: (entity: Entity) => void,
-  ) {
-    this.componentEntities.get(componentName)?.forEach((entityId) => {
-      const entity = this.getEntity(entityId);
-      if (!entity) return;
-
-      callback(entity);
-    });
-  }
-
-  public addSystem(system: System) {
-    if (!this.systemOrder.includes(system.name)) {
-      this.systemOrder.push(system.name);
-    }
-    this.systems.set(system.name, system);
-  }
-
-  public getSystem<T>(name: string): T {
-    return this.systems.get(name) as unknown as T;
-  }
-
-  public doGameLoop(timeStamp: number) {
-    if (!this.running) {
-      return;
-    }
-
-    const dt = timeStamp - this.lastTimeStamp;
-    this.lastTimeStamp = timeStamp;
-
-    // rebuild the Component -> { Entity } map
-    this.componentEntities.clear();
-    this.entities.forEach((entity) =>
-      entity.getComponents().forEach((component) => {
-        if (!this.componentEntities.has(component.name)) {
-          this.componentEntities.set(
-            component.name,
-            new Set<string>([entity.id]),
-          );
-          return;
-        }
-        this.componentEntities.get(component.name)?.add(entity.id);
-      }),
-    );
-
-    this.systemOrder.forEach((systemName) => {
-      this.systems.get(systemName)?.update(dt, this);
-    });
-  }
-}

src/engine/interfaces/Direction.ts

@@ -0,0 +1,7 @@
+export enum Direction {
+  UP = "UP",
+  DOWN = "DOWN",
+  LEFT = "LEFT",
+  RIGHT = "RIGHT",
+  NONE = "NONE",
+}

src/engine/interfaces/Draw.ts

@@ -0,0 +1,9 @@
+import type { Coord2D, Dimension2D } from "./";
+
+export interface DrawArgs {
+  center: Coord2D;
+  dimension: Dimension2D;
+  tint?: string;
+  opacity?: number;
+  rotation?: number;
+}

src/engine/interfaces/Vec2.ts

@@ -0,0 +1,25 @@
+export interface Coord2D {
+  x: number;
+  y: number;
+}
+
+export interface Dimension2D {
+  width: number;
+  height: number;
+}
+
+export interface Velocity2D {
+  dCartesian: {
+    dx: number;
+    dy: number;
+  };
+  dTheta: number;
+}
+
+export interface Force2D {
+  fCartesian: {
+    fx: number;
+    fy: number;
+  };
+  torque: number;
+}

src/engine/interfaces/index.ts

@@ -0,0 +1,3 @@
+export * from "./Vec2";
+export * from "./Draw";
+export * from "./Direction";

src/engine/systems/Render.ts

@@ -0,0 +1,50 @@
+import { System, SystemNames } from ".";
+import { BoundingBox, ComponentNames, Sprite } from "../components";
+import { Game } from "..";
+import { clamp } from "../utils";
+
+export class Render extends System {
+  private ctx: CanvasRenderingContext2D;
+
+  constructor(ctx: CanvasRenderingContext2D) {
+    super(SystemNames.Render);
+    this.ctx = ctx;
+  }
+
+  public update(dt: number, game: Game) {
+    this.ctx.clearRect(0, 0, this.ctx.canvas.width, this.ctx.canvas.height);
+
+    game.forEachEntityWithComponent(ComponentNames.Sprite, (entity) => {
+      const sprite = entity.getComponent<Sprite>(ComponentNames.Sprite);
+      sprite.update(dt);
+
+      const boundingBox = entity.getComponent<BoundingBox>(
+        ComponentNames.BoundingBox,
+      );
+
+      // don't render if we're outside the screen
+      if (
+        clamp(
+          boundingBox.center.y,
+          -boundingBox.dimension.height / 2,
+          this.ctx.canvas.height + boundingBox.dimension.height / 2,
+        ) != boundingBox.center.y ||
+        clamp(
+          boundingBox.center.x,
+          -boundingBox.dimension.width / 2,
+          this.ctx.canvas.width + boundingBox.dimension.width / 2,
+        ) != boundingBox.center.x
+      ) {
+        return;
+      }
+
+      const drawArgs = {
+        center: boundingBox.center,
+        dimension: boundingBox.dimension,
+        rotation: boundingBox.rotation,
+      };
+
+      sprite.draw(this.ctx, drawArgs);
+    });
+  }
+}

src/engine/systems/index.ts

@@ -1,2 +1,3 @@
 export * from "./SystemNames";
 export * from "./System";
+export * from "./Render";

src/engine/utils/clamp.ts

@@ -0,0 +1,2 @@
+export const clamp = (num: number, min: number, max: number) =>
+  Math.min(Math.max(num, min), max);

src/engine/utils/dotProduct.ts

@@ -0,0 +1,4 @@
+import type { Coord2D } from "../interfaces";
+
+export const dotProduct = (vector1: Coord2D, vector2: Coord2D): number =>
+  vector1.x * vector2.x + vector1.y * vector2.y;

src/engine/utils/index.ts

@@ -0,0 +1,3 @@
+export * from "./clamp";
+export * from "./dotProduct";
+export * from "./rotateVector";

src/engine/utils/rotateVector.ts

@@ -0,0 +1,15 @@
+import type { Coord2D } from "../interfaces";
+
+/**
+ * ([[cos(θ), -sin(θ),])  ([x,)
+ * ([sin(θ),  cos(θ)] ])  ( y])
+ */
+export const rotateVector = (vector: Coord2D, theta: number): Coord2D => {
+  const rads = (theta * Math.PI) / 180;
+  const [cos, sin] = [Math.cos(rads), Math.sin(rads)];
+
+  return {
+    x: vector.x * cos - vector.y * sin,
+    y: vector.x * sin + vector.y * cos,
+  };
+};