101 lines
2.2 KiB
TypeScript
101 lines
2.2 KiB
TypeScript
import { mat2, vec2 } from 'gl-matrix';
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const rot90 = mat2.fromRotation(mat2.create(), Math.PI / 2);
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export function normal(out: vec2, a: vec2): vec2 {
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return vec2.transformMat2(out, a, rot90);
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}
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export function crossz(a: vec2, b: vec2): number {
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return a[0] * b[1] - a[1] * b[0];
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}
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export class Line {
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constructor(
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public readonly p: vec2,
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public readonly v: vec2,
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) {}
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public projectPointDistance(p2: vec2): number {
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const v2 = vec2.sub(vec2.create(), p2, this.p);
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return vec2.dot(this.v, v2);
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}
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public projectPoint(out: vec2, p2: vec2): vec2 {
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const d = this.projectPointDistance(p2);
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return vec2.scaleAndAdd(out, this.p, this.v, d);
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}
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public distancePoint(p2: vec2): number {
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const v2 = vec2.sub(vec2.create(), p2, this.p);
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return crossz(this.v, v2);
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}
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public intersectLine(out: vec2, l2: Line): vec2 {
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const vp = vec2.sub(vec2.create(), l2.p, this.p);
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const d = crossz(vp, this.v);
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const d2 = d / crossz(this.v, l2.v);
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return vec2.scaleAndAdd(out, l2.p, l2.v, d2);
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}
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}
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export class Movement {
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public readonly v: vec2;
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constructor(
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public readonly p1: vec2,
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public readonly p2: vec2,
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) {
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this.v = vec2.sub(vec2.create(), p2, p1);
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}
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public intersectLine(out: vec2, l: Line): vec2 {
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const vp = vec2.sub(vec2.create(), l.p, this.p1);
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const d = crossz(vp, this.v);
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const d2 = d / crossz(this.v, l.v);
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return vec2.scaleAndAdd(out, l.p, l.v, d2);
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}
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}
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export class LineSegment extends Line {
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public static fromPoints(p1: vec2, p2: vec2): LineSegment {
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const d = vec2.dist(p1, p2);
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const v = vec2.sub(vec2.create(), p2, p1);
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vec2.scale(v, v, 1 / d);
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return new LineSegment(p1, v, d);
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}
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constructor(
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p: vec2,
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v: vec2,
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public readonly l: number,
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) {
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super(p, v);
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}
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public getP2(out: vec2): vec2 {
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return vec2.scaleAndAdd(out, this.p, this.v, this.l);
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}
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public collidesPoint(p2: vec2): boolean {
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const d = this.projectPointDistance(p2);
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return (d >= 0 && d <= this.l);
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}
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public collidesMove(out: vec2, move: Movement): boolean {
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if (this.distancePoint(move.p1) < 0)
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return false;
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if (this.distancePoint(move.p2) >= 0)
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return false;
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const x = move.intersectLine(vec2.create(), this);
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if (!this.collidesPoint(x))
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return false;
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this.projectPoint(out, move.p2);
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return true;
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}
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}
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