From 54c34ca3051743fd3f1c02f73a321299af456b8a Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Sat, 1 Apr 2023 00:15:05 -0500
Subject: attempt implementing convex hull algorithm

---
 src/Terrain.js | 139 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 src/Terrain.js

(limited to 'src/Terrain.js')

diff --git a/src/Terrain.js b/src/Terrain.js
new file mode 100644
index 0000000..a51c0a3
--- /dev/null
+++ b/src/Terrain.js
@@ -0,0 +1,139 @@
+import { Mat3, Vec3, Point, RandomNormal, Shape, ConvexHull } from './Geometry.js';
+
+
+export function RandomPoints(n) {
+	const points = [];
+	for (let i=0; i<n; i++) {
+		points.push(RandomNormal());
+	}
+	return points;
+}
+
+
+export class Plate {
+	constructor(points) {
+		this.color = `hsl(${360*Math.random()}, 100%, 50%)`
+		this.points = points;
+		this.hull = ConvexHull(points);
+		let [avgX, avgY, avgZ] = [0, 0, 0];
+		for (let point of points) {
+			avgX += point.x;
+			avgY += point.y;
+			avgZ += point.z;
+		}
+		avgX /= points.length;
+		avgY /= points.length;
+		avgZ /= points.length;
+		this.center = new Vec3(avgX, avgY, avgZ).normalize();
+		this.extent = 0;
+		for (let point of points) {
+			this.extent = Math.max(this.extent, this.center.dot(point));
+		}
+
+		this.speed = Math.random();
+		this.axis = RandomNormal().cross(this.center).normalize();
+	}
+
+	filterColliding(plate) {
+		const extent = Math.max(this.extent, plate.extent);
+		return this.center.dot(plate.center) < extent;
+	}
+
+	checkColliding(plate) {
+		if (!this.filterColliding(plate)) {
+			return false;
+		}
+		
+		console.log("check", this, plate);
+
+		const threshold = 0.00001;
+		let collisionTotal = 0;
+		for (let pa of this.points) {
+			for (let pb of plate.points) {
+				collisionTotal += pa.dot(pb);
+			}
+		}
+		collisionTotal /= this.points.length * plate.points.length;
+		console.log(this, plate, collisionTotal);
+		if (collisionTotal > threshold) {
+			return true;
+		}
+		return false;
+	}
+
+	move() {
+		const matrix = new Mat3().rotation(this.axis, this.speed * 0.01 * Math.PI);
+		for (let i=0; i<this.points.length; i++) {
+			this.points[i] = matrix.mulv(this.points[i]);
+		}
+		this.hull.translate(this.axis, this.speed * 0.01 * Math.PI);
+		this.center = matrix.mulv(this.center);
+	}
+
+	render(ct, view) {
+		ct.fillStyle = this.color;
+		for (let point of this.points) {
+			point.render(ct, view);
+		}
+		this.hull.render(ct, view);
+	}
+}
+
+
+function randomChoice(array) {
+	const index = Math.floor(array.length * Math.random());
+	return array[index];
+}
+
+
+export class PlateManager {
+	constructor(points, plateCount) {
+		this.points = points;
+		this.plates = this.buildPlates(plateCount);
+	}
+
+
+	buildPlates(plateCount) {
+		const seedPoints = [];
+		const points = [];
+		for (let i=0; i<plateCount; i++) {
+			seedPoints.push(randomChoice(this.points));
+			points.push([]);
+		}
+		
+		for (let point of this.points) {
+			let maxDot = -1;
+			let index = -1;
+			for (let i=0; i<plateCount; i++) {
+				const seed = seedPoints[i];
+				const d = seed.dot(point);
+				if (d > maxDot) {
+					maxDot = d;
+					index = i;
+				}
+			}
+			if (index == -1) {
+				console.error("no closest point", point);
+			}
+			points[index].push(point);
+		}
+
+		const plates = [];
+		for (let p of points) {
+			plates.push(new Plate(p));
+		}
+		return plates;
+	}
+
+	update() {
+		for (let plate of this.plates) {
+			plate.move();
+		}
+	}
+
+	render(ct, view) {
+		for (let plate of this.plates) {
+			plate.render(ct, view);
+		}
+	}
+}
-- 
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