A (not so) simple d3-inertia example.
The offset is t * (1-t) * velocity, which allows the drawing to come back to its original place after n seconds.
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January 1, 2020 16:19
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Inertia and back
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| license: mit |
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| <!doctype html> | |
| <html> | |
| <head> | |
| <script src="https://unpkg.com/d3"></script> | |
| <script src="https://unpkg.com/d3-inertia"></script> | |
| <style> | |
| svg { | |
| cursor: move; /* fallback if grab cursor is unsupported */ | |
| cursor: grab; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <svg></svg> | |
| <script> | |
| const width = 960, height = 500, margin = 10; | |
| const svg = d3.select("svg").attr('width', width).attr('height', height); | |
| var dots = d3.range(100) | |
| .map(d => | |
| [Math.random()*width, Math.random()*height, 0.2 * (0.5 - Math.random()) * 2 * Math.PI] | |
| ); | |
| svg.selectAll('circle') | |
| .data(dots) | |
| .enter() | |
| .append('circle') | |
| .attr('cx', d => d[0]) | |
| .attr('cy', d => d[1]) | |
| .attr('r', d => Math.random() * 50) | |
| .attr('fill-opacity', 0.1) | |
| .attr('fill', d => d[2] > 0 ? 'orange' : 'pink') | |
| .attr('stroke', 'lightblue') | |
| function draw(offset) { | |
| svg.selectAll('circle') | |
| .attr('cx', d => d[0] + offset[0] * Math.cos(d[2]) + offset[1] * Math.sin(d[2])) | |
| .attr('cy', d => d[1] + offset[1] * Math.cos(d[2]) - offset[0] * Math.sin(d[2])) | |
| } | |
| var n = 10000; // reference time in ms | |
| var position = [0,0], startposition, endposition; | |
| var inertia = d3.inertiaHelper({ | |
| start: function(){ | |
| startposition = inertia.position; | |
| }, | |
| move: function(){ | |
| draw([position[0] + inertia.position[0] - startposition[0], | |
| position[1] + inertia.position[1] - startposition[1]]) | |
| }, | |
| end: function(){ | |
| position = endposition = [position[0] + inertia.position[0] - startposition[0], | |
| position[1] + inertia.position[1] - startposition[1]] | |
| }, | |
| render: function(t) { | |
| position = [endposition[0] + t * (1-t) * inertia.velocity[0], | |
| endposition[1] + t * (1-t) * inertia.velocity[1]]; | |
| draw(position) | |
| }, | |
| time: n | |
| }); | |
| svg.call( | |
| d3.drag() | |
| .on("start", inertia.start) | |
| .on("drag", inertia.move) | |
| .on("end", inertia.end) | |
| ); | |
| </script> | |
| </body> | |
| </html> |
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