increase collision performance _heavily_

client/src/JumpStorm.ts

@@ -1,5 +1,7 @@
 import { Floor, Player } from "@engine/entities";
 import { Game } from "@engine/Game";
+import { Grid } from "@engine/structures";
+import { Miscellaneous } from "@engine/config";
 import {
   WallBounds,
   FacingDirection,
@@ -65,11 +67,16 @@ export class JumpStorm {
       socket,
     );
 
+    const grid = new Grid(
+      { width: Miscellaneous.WIDTH, height: Miscellaneous.HEIGHT },
+      { width: 30, height: 30 },
+    );
+
     [
       this.createInputSystem(),
       new FacingDirection(),
       new Physics(),
-      new Collision(),
+      new Collision(grid),
       new WallBounds(ctx.canvas.width),
       new NetworkUpdate(
         clientSocketMessageQueueProvider,

engine/components/BoundingBox.ts

@@ -17,6 +17,25 @@ export class BoundingBox extends Component {
 
   // https://en.wikipedia.org/wiki/Hyperplane_separation_theorem
   public isCollidingWith(box: BoundingBox): boolean {
+    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;
+    }
+
     const boxes = [this.getVertices(), box.getVertices()];
     for (const poly of boxes) {
       for (let i = 0; i < poly.length; i++) {
@@ -83,4 +102,18 @@ export class BoundingBox extends Component {
       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,
+    };
+  }
 }

engine/entities/Floor.ts

@@ -23,7 +23,10 @@ export class Floor extends Entity {
 
     this.addComponent(
       new BoundingBox(
-        { x: 300, y: 300 },
+        {
+          x: 300,
+          y: 300,
+        },
         { width, height: Floor.spriteSpec.height },
       ),
     );

engine/entities/Player.ts

@@ -18,7 +18,7 @@ import { Direction } from "../interfaces";
 
 export class Player extends Entity {
   private static MASS: number = 10;
-  private static MOI: number = 1000;
+  private static MOI: number = 100;
 
   private static spriteSpec: SpriteSpec = SPRITE_SPECS.get(
     Sprites.COFFEE,
@@ -29,7 +29,10 @@ export class Player extends Entity {
 
     this.addComponent(
       new BoundingBox(
-        { x: 300, y: 100 },
+        {
+          x: 300,
+          y: 100,
+        },
         { width: Player.spriteSpec.width, height: Player.spriteSpec.height },
         0,
       ),

engine/structures/Grid.ts

@@ -0,0 +1,97 @@
+import type { Coord2D, Dimension2D } from "../interfaces";
+import type { RefreshingCollisionFinderBehavior } from ".";
+
+export class Grid implements RefreshingCollisionFinderBehavior {
+  private cellEntities: Map<number, string[]>;
+
+  private gridDimension: Dimension2D;
+  private cellDimension: Dimension2D;
+  private topLeft: Coord2D;
+
+  constructor(
+    gridDimension: Dimension2D,
+    cellDimension: Dimension2D,
+    topLeft = { x: 0, y: 0 },
+  ) {
+    this.gridDimension = gridDimension;
+    this.cellDimension = cellDimension;
+    this.topLeft = topLeft;
+
+    this.cellEntities = new Map();
+  }
+
+  public insert(boxedEntry: BoxedEntry) {
+    this.getOverlappingCells(boxedEntry).forEach((gridIdx) => {
+      if (!this.cellEntities.has(gridIdx)) {
+        this.cellEntities.set(gridIdx, []);
+      }
+      this.cellEntities.get(gridIdx).push(boxedEntry.id);
+    });
+  }
+
+  public getNeighborIds(boxedEntry: BoxedEntry): Set<string> {
+    const neighborIds: Set<string> = new Set();
+    this.getOverlappingCells(boxedEntry).forEach((gridIdx) => {
+      if (this.cellEntities.has(gridIdx)) {
+        this.cellEntities.get(gridIdx).forEach((id) => neighborIds.add(id));
+      }
+    });
+    return neighborIds;
+  }
+
+  public clear() {
+    this.cellEntities.clear();
+  }
+
+  public setTopLeft(topLeft: Coord2D) {
+    this.topLeft = topLeft;
+  }
+
+  public setDimension(dimension: Dimension2D) {
+    this.gridDimension = dimension;
+  }
+
+  public setCellDimension(cellDimension: Dimension2D) {
+    this.cellDimension = cellDimension;
+  }
+
+  private getOverlappingCells(boxedEntry: BoxedEntry): number[] {
+    const { center, dimension } = boxedEntry;
+    const yBoxes = Math.ceil(
+      this.gridDimension.height / this.cellDimension.height,
+    );
+    const xBoxes = Math.ceil(
+      this.gridDimension.width / this.cellDimension.width,
+    );
+
+    const translated: Coord2D = {
+      y: center.y - this.topLeft.y,
+      x: center.x - this.topLeft.x,
+    };
+
+    const topLeftBox = {
+      x: Math.floor(
+        (translated.x - dimension.width / 2) / this.cellDimension.width,
+      ),
+      y: Math.floor(
+        (translated.y - dimension.height / 2) / this.cellDimension.height,
+      ),
+    };
+    const bottomRightBox = {
+      x: Math.floor(
+        (translated.x + dimension.width / 2) / this.cellDimension.width,
+      ),
+      y: Math.floor(
+        (translated.y + dimension.height / 2) / this.cellDimension.height,
+      ),
+    };
+
+    const cells: number[] = [];
+
+    for (let y = topLeftBox.y; y <= bottomRightBox.y; ++y)
+      for (let x = topLeftBox.x; x <= bottomRightBox.x; ++x)
+        cells.push(yBoxes * y + x);
+
+    return cells;
+  }
+}

engine/structures/QuadTree.ts

@@ -1,10 +1,5 @@
 import type { Coord2D, Dimension2D } from "../interfaces";
-
-export interface BoxedEntry {
-  id: string;
-  dimension: Dimension2D;
-  center: Coord2D;
-}
+import type { BoxedEntry, RefreshingCollisionFinderBehavior } from ".";
 
 enum Quadrant {
   I,
@@ -13,7 +8,14 @@ enum Quadrant {
   IV,
 }
 
-export class QuadTree {
+/*
+  unused due to performance problems. here anyways, in case it _really_ is necessary at some point
+  (and to justify the amount of time i spent here).
+*/
+export class QuadTree implements RefreshingCollisionFinderBehavior {
+  private static readonly QUADTREE_MAX_LEVELS = 3;
+  private static readonly QUADTREE_SPLIT_THRESHOLD = 2000;
+
   private maxLevels: number;
   private splitThreshold: number;
   private level: number;
@@ -24,18 +26,18 @@ export class QuadTree {
   private objects: BoxedEntry[];
 
   constructor(
-    topLeft: Coord2D,
+    topLeft: Coord2D = { x: 0, y: 0 },
     dimension: Dimension2D,
-    maxLevels: number,
-    splitThreshold: number,
-    level?: number,
+    maxLevels: number = QuadTree.QUADTREE_MAX_LEVELS,
+    splitThreshold: number = QuadTree.QUADTREE_SPLIT_THRESHOLD,
+    level: number = 0,
   ) {
     this.children = new Map<Quadrant, QuadTree>();
     this.objects = [];
 
     this.maxLevels = maxLevels;
     this.splitThreshold = splitThreshold;
-    this.level = level ?? 0;
+    this.level = level;
 
     this.topLeft = topLeft;
     this.dimension = dimension;
@@ -45,7 +47,7 @@ export class QuadTree {
     if (this.hasChildren()) {
       this.getQuadrants(boxedEntry).forEach((quadrant) => {
         const quadrantBox = this.children.get(quadrant);
-        quadrantBox?.insert(boxedEntry);
+        quadrantBox!.insert(boxedEntry);
       });
       return;
     }
@@ -73,15 +75,16 @@ export class QuadTree {
   }
 
   public getNeighborIds(boxedEntry: BoxedEntry): string[] {
-    const neighbors: string[] = this.objects.map(({ id }) => id);
+    const neighbors = new Set<string>(
+      this.objects.map(({ id }) => id).filter((id) => id != boxedEntry.id),
+    );
 
     if (this.hasChildren()) {
       this.getQuadrants(boxedEntry).forEach((quadrant) => {
         const quadrantBox = this.children.get(quadrant);
-
         quadrantBox
           ?.getNeighborIds(boxedEntry)
-          .forEach((id) => neighbors.push(id));
+          .forEach((id) => neighbors.add(id));
       });
     }
 
@@ -158,9 +161,9 @@ export class QuadTree {
 
   private realignObjects(): void {
     this.objects.forEach((boxedEntry) => {
-      this.getQuadrants(boxedEntry).forEach((direction) => {
-        const quadrant = this.children.get(direction);
-        quadrant?.insert(boxedEntry);
+      this.getQuadrants(boxedEntry).forEach((quadrant) => {
+        const quadrantBox = this.children.get(quadrant);
+        quadrantBox!.insert(boxedEntry);
       });
     });
 

engine/structures/RefreshingCollisionFinderBehavior.ts

@@ -0,0 +1,14 @@
+import type { Coord2D, Dimension2D } from "../interfaces";
+
+export interface BoxedEntry {
+  id: string;
+  dimension: Dimension2D;
+  center: Coord2D;
+}
+
+export interface RefreshingCollisionFinderBehavior {
+  public clear(): void;
+  public insert(boxedEntry: BoxedEntry): void;
+  public getNeighborIds(boxedEntry: BoxedEntry): Set<string>;
+  public setTopLeft(topLeft: Coord2d): void;
+}

engine/structures/index.ts

@@ -1 +1,3 @@
+export * from "./RefreshingCollisionFinderBehavior";
 export * from "./QuadTree";
+export * from "./Grid";

engine/systems/Collision.ts

@@ -8,58 +8,49 @@ import {
   Forces,
 } from "../components";
 import { Game } from "../Game";
-import { PhysicsConstants } from "../config";
+import { Miscellaneous, PhysicsConstants } from "../config";
 import { Entity } from "../entities";
 import type { Coord2D, Dimension2D, Velocity2D } from "../interfaces";
-import { QuadTree, BoxedEntry } from "../structures";
+import { BoxedEntry, RefreshingCollisionFinderBehavior } from "../structures";
 
 export class Collision extends System {
   private static readonly COLLIDABLE_COMPONENT_NAMES = [
     ComponentNames.Collide,
     ComponentNames.TopCollidable,
   ];
-  private static readonly QUADTREE_MAX_LEVELS = 10;
-  private static readonly QUADTREE_SPLIT_THRESHOLD = 10;
 
-  private quadTree: QuadTree;
+  private collisionFinder: RefreshingCollisionFinderBehavior;
 
-  constructor(screenDimensions: Dimension2D) {
+  constructor(refreshingCollisionFinder: RefreshingCollisionFinderBehavior) {
     super(SystemNames.Collision);
 
-    this.quadTree = new QuadTree(
-      { x: 0, y: 0 },
-      screenDimensions,
-      Collision.QUADTREE_MAX_LEVELS,
-      Collision.QUADTREE_SPLIT_THRESHOLD,
-    );
+    this.collisionFinder = refreshingCollisionFinder;
   }
 
   public update(_dt: number, game: Game) {
-    // rebuild the quadtree
-    this.quadTree.clear();
+    this.collisionFinder.clear();
 
-    const entitiesToAddToQuadtree: Entity[] = [];
+    const entitiesToAddToCollisionFinder: Entity[] = [];
 
     Collision.COLLIDABLE_COMPONENT_NAMES.map((componentName) =>
       game.forEachEntityWithComponent(componentName, (entity) => {
         if (!entity.hasComponent(ComponentNames.BoundingBox)) {
           return;
         }
-        entitiesToAddToQuadtree.push(entity);
+        entitiesToAddToCollisionFinder.push(entity);
       }),
     );
 
-    this.insertEntitiesInQuadTreeAndUpdateBounds(entitiesToAddToQuadtree);
-
-    this.findCollidingEntitiesAndCollide(entitiesToAddToQuadtree, game);
+    this.insertEntitiesAndUpdateBounds(entitiesToAddToCollisionFinder);
+    this.findCollidingEntitiesAndCollide(entitiesToAddToCollisionFinder, game);
   }
 
-  private insertEntitiesInQuadTreeAndUpdateBounds(entities: Entity[]) {
+  private insertEntitiesAndUpdateBounds(entities: Entity[]) {
+    const collisionFinderInsertions: BoxedEntry[] = [];
+
     const topLeft: Coord2D = { x: Infinity, y: Infinity };
     const bottomRight: Coord2D = { x: -Infinity, y: -Infinity };
 
-    const quadTreeInsertions: BoxedEntry[] = [];
-
     entities.forEach((entity) => {
       const boundingBox = entity.getComponent<BoundingBox>(
         ComponentNames.BoundingBox,
@@ -71,21 +62,15 @@ export class Collision extends System {
       }
 
       const { center } = boundingBox;
-      const topLeftBoundingBox = {
-        x: center.x - dimension.width / 2,
-        y: center.y - dimension.height / 2,
-      };
-      const bottomRightBoundingBox = {
-        x: center.x + dimension.width / 2,
-        y: center.y + dimension.height / 2,
-      };
+      const topLeftBoundingBox = boundingBox.getTopLeft();
+      const bottomRightBoundingBox = boundingBox.getBottomRight();
 
       topLeft.x = Math.min(topLeftBoundingBox.x, topLeft.x);
       topLeft.y = Math.min(topLeftBoundingBox.y, topLeft.y);
       bottomRight.x = Math.max(bottomRightBoundingBox.x, bottomRight.x);
-      bottomRight.y = Math.min(bottomRightBoundingBox.y, bottomRight.y);
+      bottomRight.y = Math.max(bottomRightBoundingBox.y, bottomRight.y);
 
-      quadTreeInsertions.push({
+      collisionFinderInsertions.push({
         id: entity.id,
         dimension,
         center,
@@ -94,16 +79,16 @@ export class Collision extends System {
 
     // set bounds first
     if (entities.length > 0) {
-      this.quadTree.setTopLeft(topLeft);
-      this.quadTree.setDimension({
+      this.collisionFinder.setTopLeft(topLeft);
+      this.collisionFinder.setDimension({
         width: bottomRight.x - topLeft.x,
         height: bottomRight.y - topLeft.y,
       });
     }
 
     // then, begin insertions
-    quadTreeInsertions.forEach((boxedEntry: BoxedEntry) =>
-      this.quadTree.insert(boxedEntry),
+    collisionFinderInsertions.forEach((boxedEntry: BoxedEntry) =>
+      this.collisionFinder.insert(boxedEntry),
     );
   }
 
@@ -181,15 +166,13 @@ export class Collision extends System {
         ComponentNames.BoundingBox,
       );
 
-      const neighborIds = this.quadTree
-        .getNeighborIds({
+      const neighborIds = this.collisionFinder.getNeighborIds({
         id: entity.id,
         dimension: boundingBox.dimension,
         center: boundingBox.center,
-        })
-        .filter((neighborId) => neighborId != entity.id);
+      });
 
-      neighborIds.forEach((neighborId) => {
+      for (const neighborId of neighborIds) {
         const neighbor = game.getEntity(neighborId);
         if (!neighbor) return;
 
@@ -200,7 +183,7 @@ export class Collision extends System {
         if (boundingBox.isCollidingWith(neighborBoundingBox)) {
           collidingEntityIds.push([entity.id, neighborId]);
         }
-      });
+      }
     }
 
     return collidingEntityIds;