Created
August 22, 2019 17:49
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Convex hull with JavaScript and p5.js
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| <html> | |
| <head> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.9.0/p5.js"></script> | |
| <script src="sketch.js"></script> | |
| </head> | |
| <body> | |
| <div id="canvas"></div> | |
| <input type="button" id="btnGo" value="Go" onclick="btnGoClicked()"> | |
| </body> | |
| </html> |
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| let width = 640, | |
| height = 480; | |
| let points = []; | |
| let donePoints = []; | |
| function setup() { | |
| let cnv = createCanvas(width, height); | |
| cnv.parent("canvas"); | |
| background(255, 0, 255); | |
| } | |
| function draw() { | |
| } | |
| function mouseClicked() { | |
| if (mouseX < width && mouseY < height) { | |
| fill(255); | |
| ellipse(mouseX, mouseY, 5, 5); | |
| points.push({ | |
| mouseX, | |
| mouseY | |
| }); | |
| } | |
| } | |
| function btnGoClicked() { | |
| for (let i=0;i<points.length-1;i++) { | |
| for (let j=i+1;j<points.length;j++) { | |
| if (points[i] != points[j]) { | |
| if(isSegmentConvex(points[i],points[j],points)){ | |
| line(points[i].mouseX,points[i].mouseY,points[j].mouseX,points[j].mouseY); | |
| } | |
| } | |
| } | |
| } | |
| } | |
| function isSegmentConvex(point1, point2, points) { | |
| let side=null; | |
| for (const point of points) { | |
| if (point != point1 && point != point2) { | |
| let d=(point.mouseX-point1.mouseX)*(point2.mouseY-point1.mouseY)-(point.mouseY-point1.mouseY)*(point2.mouseX-point1.mouseX); | |
| if(side==null){ | |
| side=d; | |
| } | |
| if(d*side<0){//if 'd' and 'side' have opposite signs, there's at least one point on either side of the segment | |
| return false; | |
| } | |
| } | |
| } | |
| return true; | |
| } |
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