Bugfix the new algorithm

22d30135 · Starbeamrainbowlabs · 04b599af · 22d30135 · 22d30135 · 22d30135
Commit 22d30135 authored Oct 10, 2017 by Starbeamrainbowlabs
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Showing with 18 additions and 7 deletions

demo.html demo.html +2 -2

demo.js demo.js +2 -2

simplify_line.js simplify_line.js +14 -3

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--- a/demo.html
+++ b/demo.html
@@ -2,7 +2,7 @@
 <html>
 	<head>
 		<meta charset='utf-8' />
-		<title>Ramer Douglas Peucker Demo</title>
+		<title>Line Simplification Demo</title>
 	</head>
 	<body>
 		<canvas id="canvas-main"></canvas>
@@ -10,7 +10,7 @@
 		<div class="debug-data">
 			<ul>
 				<li>Points: <output id="output-point-count"></output> &#10142; <output id="output-simple-point-count"></output></li>
-				<li>Epsilon: <input type="range" id="input-epsilon" value="2" min="0" max="100" step="0.05" /> <output id="output-epsilon"></output>
+				<li>Min Area: <input type="range" id="input-epsilon" value="2" min="0" max="100" step="0.05" /> <output id="output-epsilon"></output>
 			</ul>
 		</div>
 		

--- a/demo.js
+++ b/demo.js
@@ -110,10 +110,10 @@ class RDPDemo
 		// Clear the screen
 		canvas.width = canvas.width;
 		
-		if(this.drawSimpleLine)
-			this.draw_line(canvas, context, this.simplePoints, this.simpleLine)
 		if(this.drawRawLine)
 			this.draw_line(canvas, context, this.points, this.rawLine);
+		if(this.drawSimpleLine)
+			this.draw_line(canvas, context, this.simplePoints, this.simpleLine)
 	}
 	
 	draw_line(canvas, context, points, settings) {

--- a/simplify_line.js
+++ b/simplify_line.js
@@ -10,10 +10,16 @@ import Vector from './lib/Vector.js';
 */
 function simplify_line(points, min_area)
 {
-	let smallest_area = Number.MAX_SAFE_INTEGER, smallest_area_i = 1;
+	// We need 3+ points to use this algorithm!
+	if(points.length < 3)
+		return points;
 	
-	while(smallest_area > min_area)
+	points = points.slice(); // Shallow clone the array
+	
+	while(true)
 	{
+		let smallest_area = Number.MAX_SAFE_INTEGER, smallest_area_i = 1;
+		
 		for(let i = 1; i < points.length - 1; i++)
 		{
 			let next_area = triangle_area(points[i - 1], points[i], points[i + 1]);
@@ -23,9 +29,14 @@ function simplify_line(points, min_area)
 			}
 		}
 		
+		if(smallest_area >= min_area || points.length <= 3)
+			break;
+		
 		// Remove the central point of the smallest triangle
 		points.splice(smallest_area_i, 1);
 	}
+	
+	return points;
 }

 /**
@@ -39,7 +50,7 @@ function triangle_area(a, b, c)
 {
 	return Math.abs(
 		(
-			a.x * (b.x - c.x) +
+			a.x * (b.y - c.y) +
 			b.x * (c.y - a.y) +
 			c.x * (a.y - b.y)
 		) / 2