Created
October 7, 2011 08:23
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| var circleCenterPt = new paper.Point(150, 300); | |
| var circleRadius = 75; | |
| var sineWaveLength = 300; | |
| var cosineWaveLength = 300; | |
| paper.setup($('canvas')[0]); | |
| var sineWaveStep = sineWaveLength/360; | |
| var cosineWaveStep = cosineWaveLength/360; | |
| var angle = 0; | |
| // Add marker | |
| var circle = new paper.Path.Circle(circleCenterPt, circleRadius); | |
| circle.strokeColor = 'blue'; | |
| // Add angle line | |
| var line = new paper.Path.Line(circleCenterPt, circleCenterPt); | |
| line.strokeColor = 'blue'; | |
| line.dashArray = [2, 2]; | |
| // Add x-axis | |
| var xAxis = new paper.Path.Line( | |
| new paper.Point(0, circleCenterPt.y), | |
| new paper.Point(circleCenterPt.x + sineWaveLength, circleCenterPt.y)); | |
| xAxis.strokeColor = 'gray'; | |
| var xAxisText = new paper.PointText(circleCenterPt.add([sineWaveLength - 100, 20])); | |
| xAxisText.fillColor = 'gray'; | |
| xAxisText.content = 'sine wave, sin(t)'; | |
| // Add y-axis | |
| var yAxis = new paper.Path.Line( | |
| new paper.Point(circleCenterPt.x, 0), | |
| new paper.Point(circleCenterPt.x, cosineWaveLength + circleCenterPt.x)); | |
| yAxis.strokeColor = 'gray'; | |
| var yAxisText = new paper.PointText(new paper.Point(circleCenterPt.x + 10, 20)); | |
| yAxisText.fillColor = 'gray'; | |
| yAxisText.content = 'cosine wave, cos(t)'; | |
| // Add circle angle marker | |
| var marker = new paper.Path.Circle(new paper.Point(10, 10), 5); | |
| marker.strokeColor = 'blue'; | |
| marker.fillColor = 'white'; | |
| // Add angle text | |
| var angleDegText = new paper.PointText(circleCenterPt.add([circleRadius, circleRadius])); | |
| angleDegText.fillColor = 'gray'; | |
| angleDegText.content = ''; | |
| var angleRadText = new paper.PointText(angleDegText.position.add([0, 20])); | |
| angleRadText.fillColor = 'gray'; | |
| angleRadText.content = ''; | |
| // Add sine path, which maps to the y-axis | |
| var sineWave = new paper.Path(); | |
| sineWave.strokeColor = 'green'; | |
| for (var i = 0; i < sineWaveLength/sineWaveStep; ++i) { | |
| sineWave.add(circleCenterPt.add([ | |
| i * sineWaveStep, | |
| Math.sin((angle + i) / 180 * Math.PI) * circleRadius | |
| ])); | |
| } | |
| var sineWaveMarker = new paper.Path.Line(); | |
| sineWaveMarker.strokeColor = 'black'; | |
| sineWaveMarker.dashArray = [2, 2]; | |
| // Add a cosine path, which maps to the x-axis | |
| var cosineWave = new paper.Path(); | |
| cosineWave.strokeColor = 'green'; | |
| for (var i = 0; i < cosineWaveLength/cosineWaveStep; ++i) { | |
| cosineWave.add(circleCenterPt.add([ | |
| Math.cos((angle + i) / 180 * Math.PI) * circleRadius, | |
| -i * cosineWaveStep | |
| ])); | |
| } | |
| var cosineWaveMarker = new paper.Path.Line(); | |
| cosineWaveMarker.strokeColor = 'black'; | |
| cosineWaveMarker.dashArray = [2, 2]; | |
| function animate() { | |
| // Update marker position on the circle | |
| var a = (angle++) / 180 * Math.PI; | |
| marker.position.x = circleCenterPt.x + Math.cos(a) * circleRadius; | |
| marker.position.y = circleCenterPt.y - Math.sin(a) * circleRadius; | |
| line.segments[1].point = marker.position; | |
| // Update degree and (rounded) radian angle text | |
| angleDegText.content = (angle % 360) + '°'; | |
| angleRadText.content = Math.round((a % (Math.PI*2)) * 1000)/1000 + ' rad'; | |
| // Update sine wave points, essentially just moving them one step back | |
| // then add a fresh point to the current angle | |
| for (var i = sineWave.segments.length - 1; i > 0; --i) { | |
| sineWave.segments[i].point.y = sineWave.segments[i - 1].point.y; | |
| } | |
| sineWave.segments[0].point.y = marker.position.y; | |
| sineWaveMarker.segments[0].point = marker.position.clone(); | |
| sineWaveMarker.segments[1].point = sineWave.segments[0].point.clone(); | |
| // Same as above, but for the cosine points | |
| for (var i = cosineWave.segments.length - 1; i > 0; --i) { | |
| cosineWave.segments[i].point.x = cosineWave.segments[i - 1].point.x; | |
| } | |
| cosineWave.segments[0].point.x = marker.position.x; | |
| cosineWaveMarker.segments[0].point = marker.position.clone(); | |
| cosineWaveMarker.segments[1].point = cosineWave.segments[0].point.clone(); | |
| // Redraw! | |
| paper.view.draw(); | |
| requestAnimFrame(animate); | |
| } | |
| animate(); |
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