98 lines
2.8 KiB
TypeScript
98 lines
2.8 KiB
TypeScript
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import { Component, ComponentNames } from ".";
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import type { Coord2D, Dimension2D } from "../interfaces";
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import { dotProduct, rotateVector, normalizeVector } from "../utils";
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export class BoundingBox extends Component {
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public center: Coord2D;
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public dimension: Dimension2D;
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public rotation: number;
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constructor(center: Coord2D, dimension: Dimension2D, rotation?: number) {
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super(ComponentNames.BoundingBox);
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this.center = center;
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this.dimension = dimension;
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this.rotation = rotation ?? 0;
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}
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public isCollidingWith(box: BoundingBox): boolean {
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const boxes = [this.getVertices(), box.getVertices()];
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for (const poly of boxes) {
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for (let i = 0; i < poly.length; ++i) {
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const [A, B] = [poly[i], poly[(i + 1) % poly.length]];
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const normal: Coord2D = { x: B.y - A.y, y: A.x - B.x };
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const [[minThis, maxThis], [minBox, maxBox]] = boxes.map((box) =>
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box.reduce(
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([min, max], vertex) => {
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const projection = dotProduct(normal, vertex);
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return [Math.min(min, projection), Math.max(max, projection)];
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},
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[Infinity, -Infinity]
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)
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);
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if (maxThis < minBox || maxBox < minThis) return false;
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}
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}
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return true;
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}
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public getVertices(): Coord2D[] {
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return [
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{ x: -this.dimension.width / 2, y: -this.dimension.height / 2 },
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{ x: -this.dimension.width / 2, y: this.dimension.height / 2 },
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{ x: this.dimension.width / 2, y: this.dimension.height / 2 },
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{ x: this.dimension.width / 2, y: -this.dimension.height / 2 },
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]
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.map((vertex) => rotateVector(vertex, this.rotation))
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.map((vertex) => {
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return {
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x: vertex.x + this.center.x,
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y: vertex.y + this.center.y,
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};
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});
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}
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private getAxes() {
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const corners: Coord2D[] = this.getVerticesRelativeToCenter();
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const axes: Coord2D[] = [];
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for (let i = 0; i < corners.length; ++i) {
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const [cornerA, cornerB] = [
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corners[i],
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corners[(i + 1) % corners.length],
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].map((corner) => rotateVector(corner, this.rotation));
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axes.push(
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normalizeVector({
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x: cornerB.y - cornerA.y,
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y: -(cornerB.x - cornerA.x),
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})
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);
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}
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return axes;
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}
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private project(axis: Coord2D): [number, number] {
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const corners = this.getCornersRelativeToCenter();
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let [min, max] = [Infinity, -Infinity];
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for (const corner of corners) {
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const rotated = rotateVector(corner, this.rotation);
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const translated = {
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x: rotated.x + this.center.x,
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y: rotated.y + this.center.y,
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};
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const projection = dotProduct(translated, axis);
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min = Math.min(projection, min);
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max = Math.max(projection, max);
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}
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return [min, max];
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}
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}
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