From 9ccb4a7bc728fd0e85c04fddb802fde02b73cfe2 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Sun, 29 May 2022 20:44:11 -0500
Subject: add basic color brushing demo

---
 src/Canvas.js          |   4 ++
 src/Terrain.js         | 111 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.js            |  30 ++++++++-----
 src/modules/Terrain.js | 111 -------------------------------------------------
 4 files changed, 135 insertions(+), 121 deletions(-)
 create mode 100644 src/Terrain.js
 delete mode 100644 src/modules/Terrain.js

diff --git a/src/Canvas.js b/src/Canvas.js
index 7f6404b..6dff7bd 100644
--- a/src/Canvas.js
+++ b/src/Canvas.js
@@ -22,6 +22,8 @@ class Canvas {
 		/* callbacks */
 		this.onDraw = null;
 		this.onMouseMove = null;
+		this.onMouseDown = null;
+		this.onMouseUp = null;
 
 		/* register event listeners */
 
@@ -53,9 +55,11 @@ class Canvas {
 		this.element.addEventListener('mousedown', e => {
 			e.preventDefault();
 			if (e.button === 1) this.panning = true;
+			if (this.onMouseDown) this.onMouseDown(e);
 		});
 		this.element.addEventListener('mouseup', e => {
 			if (e.button === 1) this.panning = false;
+			if (this.onMouseUp) this.onMouseUp(e);
 		}); 
 
 		/* mouse leave */
diff --git a/src/Terrain.js b/src/Terrain.js
new file mode 100644
index 0000000..c287063
--- /dev/null
+++ b/src/Terrain.js
@@ -0,0 +1,111 @@
+'use strict';
+
+import Voronoi from './3rdparty/rhill-voronoi-core.js';
+
+import { useAverage } from './modules/Util.js';
+import { AABB, QuadTree } from './modules/Geometry.js';
+
+
+/* from here on up, we always assume that points live in the range [(0,0), (1,1)) */
+
+function lloydRelax(point_set, density) {
+	/* setup quadtree and averages */
+	let tree = new QuadTree(1,1);
+	let averages = {};
+	for (let i=0; i<point_set.length; i++) {
+		const point = point_set[i];
+		point.index = i;
+		tree.insert(point);
+
+		let [avg, append] = useAverage();
+		const cent_x = { avg, append };
+		[avg, append] = useAverage();
+		const cent_y = { avg, append };
+		averages[i] = { cent_x, cent_y };
+	}
+
+	/* compute average centroids */
+	for (let x=0; x<1; x += 1/density) {
+		for (let y=0; y<1; y += 1/density) {
+			const point = { x, y };
+			const closest = tree.closest(point);
+			const { cent_x, cent_y } = averages[closest.index];
+			cent_x.append(point.x);
+			cent_y.append(point.y);
+		}
+	}
+
+	/* return centroid points */
+	const result = [];
+	for (let i=0; i<point_set.length; i++) {
+		const point = { x: averages[i].cent_x.avg(), y: averages[i].cent_y.avg() };
+		result.push(point);
+	}
+	return result;
+}
+
+
+class Terrain {
+	constructor() {
+		const N_SEED_POINTS = 2**12;
+		const N_RELAX_ITERATIONS = 1;
+		const RELAX_DENSITY = 400;
+		const randomPoint = () => ({x: Math.random(), y: Math.random()});
+
+		this.min_height = 0;
+		this.max_height = 0;
+
+		let seed_points = [];
+		for (let i=0; i<N_SEED_POINTS; i++) seed_points.push(randomPoint());
+
+		for (let i=0; i<N_RELAX_ITERATIONS; i++)
+			lloydRelax(seed_points, RELAX_DENSITY);
+
+		const v = new Voronoi();
+		this.graph = v.compute(seed_points, {xl: 0, xr: 1, yt: 0, yb: 1});
+
+		this.tree = new QuadTree(1,1);
+		for (let v of this.graph.vertices) {
+			v.hue = 0;
+			this.tree.insert(v);
+		}
+	}
+
+
+	applyBrush(x, y, f, strength, radius) {
+		const region = new AABB(x-radius, y-radius, 2*radius, 2*radius);
+		const points = this.tree.root.getPointsInRegion(region);
+		
+		const dist2 = (a, b) => (a.x - b.x)**2 + (a.y - b.y)**2;
+
+		const sigma = radius/3;
+		const beta = 1/(2*sigma*sigma);
+		const center = { x, y };
+		const power = pt => Math.exp(-beta * dist2(pt, center));
+		
+		for (let pt of points) f(pt, strength * power(pt));
+	}
+
+
+	renderGrid(ct) {
+		ct.save();
+		ct.lineWidth = 0.001;
+		for (let edge of this.graph.edges) {
+			ct.fillStyle = `hsl(${edge.va.hue}, 100%, 50%)`;
+			ct.beginPath();
+			ct.arc(edge.va.x, edge.va.y, 0.005, 0, 2*Math.PI);
+			ct.closePath();
+			ct.fill();
+
+			ct.beginPath();
+			ct.moveTo(edge.va.x, edge.va.y);
+			ct.lineTo(edge.vb.x, edge.vb.y);
+			ct.closePath();
+			ct.stroke();
+		}
+		ct.restore();
+	}
+}
+
+export { lloydRelax };
+export default Terrain;
diff --git a/src/main.js b/src/main.js
index d618d05..4527a90 100644
--- a/src/main.js
+++ b/src/main.js
@@ -1,27 +1,37 @@
+import Terrain from './Terrain.js';
 import Canvas from './Canvas.js';
 
 const $ = id => document.getElementById(id)
 
 window.onload = () => {
 	const canvas = new Canvas('root');
+	const terrain = new Terrain();
+
+	const BRUSH_RADIUS = 80;
+	let brushing = false;
+	canvas.onMouseDown = e => {
+		if (e.button == 0) brushing = true;
+	};
+	canvas.onMouseUp = e => {
+		if (e.button == 0) brushing = false;
+	};
 
 	const pos = canvas.mouse.drawingPos;
-	canvas.onMouseMove = () => canvas.draw();
+	canvas.onMouseMove = () => {
+		if (brushing)
+			terrain.applyBrush(pos.x, pos.y, (pt, strength) => {
+				pt.hue += 10 * strength;		
+			}, 1, canvas.pixelsToUnits(BRUSH_RADIUS));
+		canvas.draw();
+	};
 	
 	canvas.onDraw = ct => {
-		ct.fillStyle = '#f00';
-		ct.fillRect(0, 0, 1/3, 1/3);
-		ct.fillStyle = '#0f0';
-		ct.fillRect(2/3, 0, 1/3, 1/3);
-		ct.fillStyle = '#ff0';
-		ct.fillRect(0, 2/3, 1/3, 1/3);
-		ct.fillStyle = '#00f';
-		ct.fillRect(2/3, 2/3, 1/3, 1/3);
+		terrain.renderGrid(ct);
 
 		ct.strokeStyle = '#fff';
 		ct.lineWidth = canvas.pixelsToUnits(1);
 		ct.beginPath();
-		ct.arc(pos.x, pos.y, canvas.pixelsToUnits(30), 0, 2*Math.PI);
+		ct.arc(pos.x, pos.y, canvas.pixelsToUnits(BRUSH_RADIUS), 0, 2*Math.PI);
 		ct.closePath();
 		ct.stroke();
 	};
diff --git a/src/modules/Terrain.js b/src/modules/Terrain.js
deleted file mode 100644
index 21908ac..0000000
--- a/src/modules/Terrain.js
+++ /dev/null
@@ -1,111 +0,0 @@
-'use strict';
-
-import Voronoi from './3rdparty/rhill-voronoi-core.js';
-
-import { useAverage } from './Util.js';
-import { AABB, QuadTree } from './Geometry.js';
-
-
-/* from here on up, we always assume that points live in the range [(0,0), (1,1)) */
-
-function lloydRelax(point_set, density) {
-	/* setup quadtree and averages */
-	let tree = new QuadTree(1,1);
-	let averages = {};
-	for (let i=0; i<point_set.length; i++) {
-		const point = point_set[i];
-		point.index = i;
-		tree.insert(point);
-
-		let [avg, append] = useAverage();
-		const cent_x = { avg, append };
-		[avg, append] = useAverage();
-		const cent_y = { avg, append };
-		averages[i] = { cent_x, cent_y };
-	}
-
-	/* compute average centroids */
-	for (let x=0; x<1; x += 1/density) {
-		for (let y=0; y<1; y += 1/density) {
-			const point = { x, y };
-			const closest = tree.closest(point);
-			const { cent_x, cent_y } = averages[closest.index];
-			cent_x.append(point.x);
-			cent_y.append(point.y);
-		}
-	}
-
-	/* return centroid points */
-	const result = [];
-	for (let i=0; i<point_set.length; i++) {
-		const point = { x: averages[i].cent_x.avg(), y: averages[i].cent_y.avg() };
-		result.push(point);
-	}
-	return result;
-}
-
-
-class Terrain {
-	constructor() {
-		const N_SEED_POINTS = 2**12;
-		const N_RELAX_ITERATIONS = 1;
-		const RELAX_DENSITY = 400;
-		const randomPoint = () => ({x: Math.random(), y: Math.random()});
-
-		this.min_height = 0;
-		this.max_height = 0;
-
-		let seed_points = [];
-		for (let i=0; i<N_SEED_POINTS; i++) seed_points.push(randomPoint());
-
-		for (let i=0; i<N_RELAX_ITERATIONS; i++)
-			lloydRelax(seed_points, RELAX_DENSITY);
-
-		const v = new Voronoi();
-		this.graph = v.compute(seed_points, {xl: 0, xr: 1, yt: 0, yb: 1});
-
-		this.tree = new QuadTree(1,1);
-		for (let v of this.graph.vertices) {
-			v.height = 0;
-			this.tree.insert(v);
-		}
-	}
-
-
-	applyBrush(x, y, f, strength, radius) {
-		const region = new AABB(x-radius, y-radius, 2*radius, 2*radius);
-		const points = this.tree.root.getPointsInRegion(region);
-		
-		const dist2 = (a, b) => (a.x - b.x)**2 + (a.y - b.y)**2;
-
-		const sigma = radius/3;
-		const beta = 1/(2*sigma*sigma);
-		const center = { x, y };
-		const power = pt => Math.exp(-beta * dist2(pt, center));
-		
-		for (let pt of points) f(pt, strength * power(pt));
-	}
-
-
-	renderGrid(ct) {
-		ct.save();
-		ct.lineWidth = 0.001;
-		for (let edge of this.graph.edges) {
-			ct.fillStyle = `hsl(${edge.va.height}, 100%, 50%)`;
-			ct.beginPath();
-			ct.arc(edge.va.x, edge.va.y, 0.005, 0, 2*Math.PI);
-			ct.closePath();
-			ct.fill();
-
-			ct.beginPath();
-			ct.moveTo(edge.va.x, edge.va.y);
-			ct.lineTo(edge.vb.x, edge.vb.y);
-			ct.closePath();
-			ct.stroke();
-		}
-		ct.restore();
-	}
-}
-
-export { lloydRelax };
-export default Terrain;
-- 
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