Update the rope lengths using update(leftLength, rightLength).
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December 26, 2015 06:59
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Chalk drawer simulation
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| var width = 960, | |
| height = 500; | |
| var motors = [ | |
| {x: 0, y: 0}, | |
| {x: 920, y: 0} | |
| ]; | |
| var motorDistance = motors[1].x - motors[0].x; | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height) | |
| var canvas = svg.append("g") | |
| .attr("transform", "translate(" + 20 + "," + 20 + ")"); | |
| canvas.selectAll('.motor') | |
| .data(motors) | |
| .enter().append("circle") | |
| .classed("motor", true) | |
| .attr("cx", function(d) { return d.x; }) | |
| .attr("cy", function(d) { return d.y; }) | |
| .attr("r", 10); | |
| var leftRope = canvas.append("line").classed("rope", true) | |
| var rightRope = canvas.append("line").classed("rope", true) | |
| var chalk = canvas.append("circle").classed("chalk", true) | |
| function update(l1, l2) { | |
| if(l1 + l2 < motorDistance) { throw("Ropes too short!"); } | |
| if(angle(l1, l2) > Math.PI / 2) { throw("Off the left side"); } | |
| if(angle(l2, l1) > Math.PI / 2) { throw("Off the right side"); } | |
| if(Math.sin(angle(l1, l2)) * l1 > height - 20) { throw("Hit the floor"); } | |
| var data = [l1, l2]; | |
| leftRope.datum(data) | |
| .transition().ease('linear') | |
| .attr('x1', motors[0].x) | |
| .attr('y1', motors[0].y) | |
| .attr('x2', function(d) { return motors[0].x + Math.cos(angle(d[0], d[1])) * d[0]; }) | |
| .attr('y2', function(d) { return motors[0].y + Math.sin(angle(d[0], d[1])) * d[0]; }) | |
| rightRope.datum(data) | |
| .transition().ease('linear') | |
| .attr('x1', motors[1].x) | |
| .attr('y1', motors[1].y) | |
| .attr('x2', function(d) { return motors[1].x - Math.cos(angle(d[1], d[0])) * d[1]; }) | |
| .attr('y2', function(d) { return motors[1].y + Math.sin(angle(d[1], d[0])) * d[1]; }) | |
| chalk.datum(data) | |
| .transition().ease('linear') | |
| .attr("r", 10) | |
| .attr("cx", function(d) { console.log(angle(d[0], d[1])); return motors[0].x + Math.cos(angle(d[0], d[1])) * d[0]; }) | |
| .attr("cy", function(d) { return motors[0].y + Math.sin(angle(d[0], d[1])) * d[0]; }) | |
| } | |
| function angle(l1, l2) { | |
| return Math.acos((l1 * l1 + motorDistance * motorDistance - l2 * l2) / (2 * l1 * motorDistance)); | |
| } | |
| update(500, 500); |
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| <html> | |
| <head> | |
| <style> | |
| svg { | |
| fill: #000; | |
| background-color: #000; | |
| } | |
| .motor { | |
| fill: #555; | |
| } | |
| .chalk { | |
| fill: #FFF; | |
| } | |
| .rope { | |
| stroke-width: 3; | |
| stroke: #FFF; | |
| } | |
| </style> | |
| <script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script> | |
| </head> | |
| <body> | |
| <script src="chalk.js"></script> | |
| </body> | |
| </html> |
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