From fd59aaa55c39c583af86f4dc059cbe9cedd085d2 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Mon, 5 Nov 2018 19:59:39 +0100
Subject: More generic collision handling

---
 src/math/collision.ts |  7 ++++++
 src/math/line.ts      | 61 ++++++++++++---------------------------------------
 src/math/point.ts     | 40 +++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 47 deletions(-)
 create mode 100644 src/math/collision.ts
 create mode 100644 src/math/point.ts

(limited to 'src/math')

diff --git a/src/math/collision.ts b/src/math/collision.ts
new file mode 100644
index 0000000..3df811a
--- /dev/null
+++ b/src/math/collision.ts
@@ -0,0 +1,7 @@
+import { Movement } from './line';
+
+import { vec2 } from 'gl-matrix';
+
+export interface Collidable {
+	collide(out: vec2, move: Movement, r: number): boolean;
+}
diff --git a/src/math/line.ts b/src/math/line.ts
index d071779..d29bc76 100644
--- a/src/math/line.ts
+++ b/src/math/line.ts
@@ -1,4 +1,5 @@
 import { mat2, vec2 } from 'gl-matrix';
+import { Collidable } from './collision';
 
 const rot90 = mat2.fromValues(
 	0, 1,
@@ -80,7 +81,7 @@ export class Movement {
 	}
 }
 
-export class LineSegment extends Line {
+export class LineSegment extends Line implements Collidable {
 	public static fromPoints(p1: vec2, p2: vec2): LineSegment {
 		const d = vec2.dist(p1, p2);
 		const v = vec2.sub(vec2.create(), p2, p1);
@@ -101,70 +102,36 @@ export class LineSegment extends Line {
 		return vec2.scaleAndAdd(out, this.p, this.v, this.l);
 	}
 
-	public collidesPoint(p2: vec2): boolean {
+	public containsPoint(p2: vec2): boolean {
 		const d = this.projectPointDistance(p2);
 		return (d >= 0 && d <= this.l);
 	}
 
-	public collidesMove(out: vec2, move: Movement): boolean {
-		if (this.distancePoint(move.p1) < 0)
-			return false;
-
-		if (this.distancePoint(move.p2) >= 0)
-			return false;
-
-		const x = move.intersectLine(vec2.create(), this);
-		if (!this.collidesPoint(x))
-			return false;
-
-		this.projectPoint(out, move.p2);
-
-		return true;
-	}
-
-	public collidesMoveCircle(out: vec2, move: Movement, r: number): boolean {
+	public collide(out: vec2, move: Movement, r: number): boolean {
 		const t = this.getNormal(vec2.create());
 		vec2.scale(t, t, -r);
 
 		const refMove = move.translate(t);
-		const refOut = vec2.create();
 
-		if (this.collidesMove(refOut, refMove)) {
-			vec2.sub(out, refOut, t);
-			return true;
-		}
+		if (!this.collideRef(out, refMove))
+			return false;
 
-		return this.collidesPointMoveCircle(out, move, r);
+		vec2.sub(out, out, t);
+		return true;
 	}
 
-	private collidesPointMoveCircle(out: vec2, move: Movement, r: number): boolean {
-		const moveLine = move.toLineSegment();
-
-		if (moveLine.projectPointDistance(this.p) < 0)
+	private collideRef(out: vec2, move: Movement): boolean {
+		if (this.distancePoint(move.p1) < 0)
 			return false;
 
-		const d = moveLine.distancePoint(this.p) / r;
-		if (Math.abs(d) >= 1)
+		if (this.distancePoint(move.p2) >= 0)
 			return false;
 
-		const e = Math.sqrt(1 - d * d);
-
-		const t = moveLine.getNormal(vec2.create());
-		vec2.scale(t, t, d);
-		vec2.scaleAndAdd(t, t, moveLine.v, e);
-
-		const tr = vec2.scale(vec2.create(), t, r);
-
-		const refMove = move.translate(tr);
-
-		if (vec2.sqrDist(this.p, move.p1) > r * r && !refMove.passes(this.p))
+		const x = move.intersectLine(vec2.create(), this);
+		if (!this.containsPoint(x))
 			return false;
 
-		normal(t, t);
-
-		const tang = new Line(this.p, t);
-		tang.projectPoint(out, refMove.p2);
-		vec2.sub(out, out, tr);
+		this.projectPoint(out, move.p2);
 
 		return true;
 	}
diff --git a/src/math/point.ts b/src/math/point.ts
new file mode 100644
index 0000000..23a0f84
--- /dev/null
+++ b/src/math/point.ts
@@ -0,0 +1,40 @@
+import { Collidable } from './collision';
+import { Line, Movement, normal } from './line';
+
+import { vec2 } from 'gl-matrix';
+
+export class Point implements Collidable {
+	constructor(public readonly p: vec2) {}
+
+	public collide(out: vec2, move: Movement, r: number): boolean {
+		const moveLine = move.toLineSegment();
+
+		if (moveLine.projectPointDistance(this.p) < 0)
+			return false;
+
+		const d = moveLine.distancePoint(this.p) / r;
+		if (Math.abs(d) >= 1)
+			return false;
+
+		const e = Math.sqrt(1 - d * d);
+
+		const t = moveLine.getNormal(vec2.create());
+		vec2.scale(t, t, d);
+		vec2.scaleAndAdd(t, t, moveLine.v, e);
+
+		const tr = vec2.scale(vec2.create(), t, r);
+
+		const refMove = move.translate(tr);
+
+		if (vec2.sqrDist(this.p, move.p1) > r * r && !refMove.passes(this.p))
+			return false;
+
+		normal(t, t);
+
+		const tang = new Line(this.p, t);
+		tang.projectPoint(out, refMove.p2);
+		vec2.sub(out, out, tr);
+
+		return true;
+	}
+}
-- 
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