From 877e9f324cff798d547ea6622242f4b0a3e4b344 Mon Sep 17 00:00:00 2001
From: Jonathan Puckey <me@jonathanpuckey.com>
Date: Wed, 20 Apr 2011 15:41:09 +0200
Subject: [PATCH] Add port of Metaball script by Hiroyuki Sato to Examples.

---
 examples/Tools/MetaBalls.html | 116 ++++++++++++++++++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 examples/Tools/MetaBalls.html
diff --git a/examples/Tools/MetaBalls.html b/examples/Tools/MetaBalls.html
new file mode 100644
index 00000000..eb12c6be
--- /dev/null
+++ b/examples/Tools/MetaBalls.html
@@ -0,0 +1,116 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+	<title>Example</title>
+	<script type="text/javascript">var root = '../../'</script>
+	<script type="text/javascript" src="../../src/load.js"></script>
+	<script type="text/paperscript" canvas="canvas">
+		// Ported from original Metaball script by SATO Hiroyuki
+		// http://park12.wakwak.com/~shp/lc/et/en_aics_script.html
+		document.currentStyle = {
+			fillColor: 'black'
+		};
+		
+		var handle_len_rate = 2.4,
+			circlePaths = [],
+			circlePath,
+			radius = 50;
+		circlePaths.push(new Path.Circle(document.bounds.center, 100));
+		function onMouseDown(event) {
+			circlePath = null;
+			for (var i = 0, l = circlePaths.length; i < l; i++) {
+				var path = circlePaths[i];
+				if (path.position.getDistance(event.point) < 50)
+					circlePath = path;
+			}
+			if (!circlePath) {
+				circlePath = new Path.Circle(event.point, 50);
+				circlePaths.push(circlePath);
+			}
+			generateConnections(circlePaths);
+		}
+
+		function onMouseDrag(event) {
+			circlePath.position = event.point;
+			generateConnections(circlePaths);
+		}
+
+		function generateConnections(paths) {
+			for (var i = 0, l = paths.length; i < l; i++) {
+				for(var j = i - 1; j >= 0; j--){
+					var path = metaball(paths[i], paths[j], 0.5, handle_len_rate, 300);
+					if (path) {
+						path.removeOn({
+							drag: true,
+							down: true
+						});
+					}
+				}
+			}
+		}
+
+		// ---------------------------------------------
+		function metaball(ball1, ball2, v, handle_len_rate, maxDistance){
+			var center1 = ball1.position,
+				center2 = ball2.position,
+				radius1 = ball1.bounds.width / 2,
+				radius2 = ball2.bounds.width / 2,
+				pi2 = Math.PI / 2,
+				d = center1.getDistance(center2),
+				u1, u2;
+
+			if (radius1 == 0 || radius2 == 0)
+				return;
+
+			if(d > maxDistance || d <= Math.abs(radius1 - radius2)) {
+				return;
+			} else if (d < radius1 + radius2) { // case circles are overlapping
+				u1 = Math.acos((radius1 * radius1 + d * d - radius2 * radius2) / (2 * radius1 * d));
+				u2 = Math.acos((radius2 * radius2 + d * d - radius1 * radius1) / (2 * radius2 * d));
+			} else {
+				u1 = 0;
+				u2 = 0;
+			}
+
+			var angle1 = (center2 - center1).getAngleInRadians(),
+				angle2 = Math.acos((radius1 - radius2) / d),
+				angle1a = angle1 + u1 + (angle2 - u1) * v,
+				angle1b = angle1 - u1 - (angle2 - u1) * v,
+				angle2a = angle1 + Math.PI - u2 - (Math.PI - u2 - angle2) * v,
+				angle2b = angle1 - Math.PI + u2 + (Math.PI - u2 - angle2) * v;
+				p1a = center1 + getVector(angle1a, radius1),
+				p1b = center1 + getVector(angle1b, radius1),
+				p2a = center2 + getVector(angle2a, radius2),
+				p2b = center2 + getVector(angle2b, radius2),
+				// define handle length by the distance between both ends of the curve to draw
+				d2 = Math.min(v * handle_len_rate, p1a.getDistance(p2a) / (radius1 + radius2));
+
+			d2 *= Math.min(1, d * 2 / (radius1 + radius2)); // case circles are overlapping
+			radius1 *= d2;
+			radius2 *= d2;
+
+			var path = new Path([p1a, p2a, p2b, p1b]);
+			path.style = ball1.style;
+			path.closed = true;
+			var segments = path.segments;
+			segments[0].handleOut = getVector(angle1a - pi2, radius1);
+			segments[1].handleIn = getVector(angle2a + pi2, radius2);
+			segments[2].handleOut = getVector(angle2b - pi2, radius2);
+			segments[3].handleIn = getVector(angle1b + pi2, radius1);
+			return path;
+		}
+
+		// ------------------------------------------------
+		function getVector(radians, length) {
+			return new Point({
+				// Convert radians to degrees:
+				angle: radians * 180 / Math.PI,
+				length: length
+			});
+		}
+	</script>
+</head>
+<body>
+	<canvas id='canvas' width=1024 height=768></canvas>
+</body>
\ No newline at end of file
