187 lines
5.5 KiB
HTML
187 lines
5.5 KiB
HTML
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<!DOCTYPE html>
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<html><head>
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<script src="lightgl.js"></script>
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<script src="csg.js"></script>
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<script src="openjscad.js"></script>
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<style>
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body {
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font: 14px/20px 'Helvetica Neue Light', HelveticaNeue-Light, 'Helvetica Neue', Helvetica, Arial, sans-serif;
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max-width: 820px;
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margin: 0 auto;
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padding: 10px;
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}
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pre, code, textarea {
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font: 12px/20px Monaco, monospace;
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border: 1px solid #CCC;
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border-radius: 3px;
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background: #F9F9F9;
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padding: 0 3px;
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color: #555;
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}
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pre, textarea {
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padding: 10px;
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width: 100%;
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}
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textarea {
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height: 200px;
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}
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textarea:focus {
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outline: none;
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}
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canvas { cursor: move; }
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</style>
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<link rel="stylesheet" href="openjscad.css" type="text/css">
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<script>
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var gProcessor=null;
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// Show all exceptions to the user:
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OpenJsCad.AlertUserOfUncaughtExceptions();
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function onload()
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{
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gProcessor = new OpenJsCad.Processor(document.getElementById("viewer"));
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updateSolid();
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}
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function updateSolid()
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{
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gProcessor.setJsCad(document.getElementById('code').value);
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}
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</script>
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<title>OpenJsCad demo: involute gears</title>
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</head>
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<body onload="onload()">
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<h1>OpenJsCad demo: involute gears</h1>
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<div id="viewer"></div>
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<h2>Source code</h2>
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Below is the OpenJsCad script for this demo. To build your own models, create a .jscad script
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and use the <a href="processfile.html"><b>OpenJsCad parser</b></a>. For more information see the
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<a href="index.html">OpenJsCad documentation</a>.
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<br><br>
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<textarea id="code">
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// Here we define the user editable parameters:
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function getParameterDefinitions() {
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return [
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{ name: 'numTeeth', caption: 'Number of teeth:', type: 'int', default: 10 },
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{ name: 'circularPitch', caption: 'Circular pitch:', type: 'float', default: 5 },
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{ name: 'pressureAngle', caption: 'Pressure angle:', type: 'float', default: 20 },
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{ name: 'clearance', caption: 'Clearance:', type: 'float', default: 0 },
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{ name: 'thickness', caption: 'Thickness:', type: 'float', default: 5 },
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{ name: 'centerholeradius', caption: 'Radius of center hole (0 for no hole):', type: 'float', default: 2 },
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];
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}
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// Main entry point; here we construct our solid:
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function main(params)
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{
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var gear = involuteGear(
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params.numTeeth,
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params.circularPitch,
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params.pressureAngle,
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params.clearance,
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params.thickness
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);
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if(params.centerholeradius > 0)
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{
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var centerhole = CSG.cylinder({start: [0,0,-params.thickness], end: [0,0,params.thickness], radius: params.centerholeradius, resolution: 16});
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gear = gear.subtract(centerhole);
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}
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return gear;
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}
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/*
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For gear terminology see:
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http://www.astronomiainumbria.org/advanced_internet_files/meccanica/easyweb.easynet.co.uk/_chrish/geardata.htm
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Algorithm based on:
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http://www.cartertools.com/involute.html
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circularPitch: The distance between adjacent teeth measured at the pitch circle
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*/
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function involuteGear(numTeeth, circularPitch, pressureAngle, clearance, thickness)
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{
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// default values:
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if(arguments.length < 3) pressureAngle = 20;
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if(arguments.length < 4) clearance = 0;
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if(arguments.length < 4) thickness = 1;
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var addendum = circularPitch / Math.PI;
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var dedendum = addendum + clearance;
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// radiuses of the 4 circles:
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var pitchRadius = numTeeth * circularPitch / (2 * Math.PI);
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var baseRadius = pitchRadius * Math.cos(Math.PI * pressureAngle / 180);
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var outerRadius = pitchRadius + addendum;
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var rootRadius = pitchRadius - dedendum;
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var maxtanlength = Math.sqrt(outerRadius*outerRadius - baseRadius*baseRadius);
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var maxangle = maxtanlength / baseRadius;
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var tl_at_pitchcircle = Math.sqrt(pitchRadius*pitchRadius - baseRadius*baseRadius);
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var angle_at_pitchcircle = tl_at_pitchcircle / baseRadius;
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var diffangle = angle_at_pitchcircle - Math.atan(angle_at_pitchcircle);
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var angularToothWidthAtBase = Math.PI / numTeeth + 2*diffangle;
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// build a single 2d tooth in the 'points' array:
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var resolution = 5;
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var points = [new CSG.Vector2D(0,0)];
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for(var i = 0; i <= resolution; i++)
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{
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// first side of the tooth:
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var angle = maxangle * i / resolution;
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var tanlength = angle * baseRadius;
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var radvector = CSG.Vector2D.fromAngle(angle);
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var tanvector = radvector.normal();
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var p = radvector.times(baseRadius).plus(tanvector.times(tanlength));
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points[i+1] = p;
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// opposite side of the tooth:
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radvector = CSG.Vector2D.fromAngle(angularToothWidthAtBase - angle);
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tanvector = radvector.normal().negated();
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p = radvector.times(baseRadius).plus(tanvector.times(tanlength));
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points[2 * resolution + 2 - i] = p;
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}
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// create the polygon and extrude into 3D:
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var tooth3d = new CSG.Polygon2D(points).extrude({offset: [0, 0, thickness]});
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var allteeth = new CSG();
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for(var i = 0; i < numTeeth; i++)
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{
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var angle = i*360/numTeeth;
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var rotatedtooth = tooth3d.rotateZ(angle);
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allteeth = allteeth.unionForNonIntersecting(rotatedtooth);
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}
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// build the root circle:
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points = [];
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var toothAngle = 2 * Math.PI / numTeeth;
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var toothCenterAngle = 0.5 * angularToothWidthAtBase;
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for(var i = 0; i < numTeeth; i++)
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{
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var angle = toothCenterAngle + i * toothAngle;
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var p = CSG.Vector2D.fromAngle(angle).times(rootRadius);
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points.push(p);
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}
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// create the polygon and extrude into 3D:
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var rootcircle = new CSG.Polygon2D(points).extrude({offset: [0, 0, thickness]});
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var result = rootcircle.union(allteeth);
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// center at origin:
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result = result.translate([0, 0, -thickness/2]);
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return result;
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}
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</textarea><br>
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<input type="submit" value="Update" onclick="updateSolid(); return false;">
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<br><br>
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</body>
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</html>
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