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Isometric Projection
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| <html> | |
| <head> | |
| <style> | |
| html, body { | |
| font-family: monospace; | |
| } | |
| .cube .side { | |
| fill-opacity: 0.4; | |
| stroke: #666; | |
| stroke-width: 0.5; | |
| } | |
| .top { fill: steelblue; } | |
| .bottom { fill: yellow; } | |
| .left { fill: brown; } | |
| .right { fill: forestgreen; } | |
| .axis { | |
| fill: none; | |
| stroke: #000; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 500; | |
| var svg = d3.select('body').append('svg') | |
| .attr('width', width) | |
| .attr('height', height); | |
| var projection = isometricProjection(); | |
| var path = isometricPath() | |
| .projection(projection); | |
| svg.append('defs').append('marker') | |
| .attr('id', 'arrow') | |
| .attr('markerWidth', 10) | |
| .attr('markerHeight', 10) | |
| .attr('refX', 0) | |
| .attr('refY', 3) | |
| .attr('orient', 'auto') | |
| .attr('markerUnits', 'strokeWidth') | |
| .append('path') | |
| .attr('d', 'M0,0L0,6L9,3Z'); | |
| var g = svg.append('g') | |
| .attr('transform', function(d) { | |
| return 'translate(' + (width / 2) + ',' + (height / 2) + ')'; | |
| }); | |
| var axes = g.append('g').attr('class', 'axes'); | |
| var axis = axes.selectAll('.axis').data(axesData()) | |
| .enter().append('g') | |
| .attr('class', 'axis'); | |
| axis.append('path') | |
| .attr('d', function(d) { return path(d.points); }) | |
| .attr('marker-end', 'url(#arrow)'); | |
| axis.append('text') | |
| .attr('transform', function(d) { | |
| var p = projection(d.labelLocation); | |
| return 'translate(' + p[0] + ',' + p[1] + ')'; | |
| }) | |
| .attr('dy', '0.33em') | |
| .style('text-anchor', 'middle') | |
| .text(function(d) { return d.label; }); | |
| var cube = g.append('g').attr('class', 'cube'); | |
| var side = cube.selectAll('path').data(cubeData()) | |
| .enter().append('path') | |
| .attr('class', function(d) { return 'side ' + d.className; }) | |
| .attr('d', function(d) { return path(d.points) + 'Z'; }); | |
| function update() { | |
| side.attr('d', function(d) { return path(d.points) + 'Z'; }); | |
| axis.select('path') | |
| .attr('d', function(d) { return path(d.points); }); | |
| axis.select('text') | |
| .attr('transform', function(d) { | |
| var p = projection(d.labelLocation); | |
| return 'translate(' + p[0] + ',' + p[1] + ')'; | |
| }); | |
| } | |
| d3.timer(function(elapsed) { | |
| projection | |
| .pitch((Math.PI / 6) * Math.sin(elapsed / 10000)) | |
| .yaw((elapsed / 2000)); | |
| update(); | |
| }); | |
| function cubeData() { | |
| return [ | |
| { | |
| className: 'bottom', | |
| points: [ | |
| [-50, -50, -50], | |
| [-50, +50, -50], | |
| [+50, +50, -50], | |
| [+50, -50, -50] | |
| ] | |
| }, | |
| { | |
| className: 'left', | |
| points: [ | |
| [+50, -50, +50], | |
| [+50, +50, +50], | |
| [+50, +50, -50], | |
| [+50, -50, -50] | |
| ] | |
| }, | |
| { | |
| className: 'right', | |
| points: [ | |
| [-50, +50, +50], | |
| [+50, +50, +50], | |
| [+50, +50, -50], | |
| [-50, +50, -50] | |
| ] | |
| }, | |
| { | |
| className: 'left', | |
| points: [ | |
| [-50, -50, +50], | |
| [-50, +50, +50], | |
| [-50, +50, -50], | |
| [-50, -50, -50] | |
| ] | |
| }, | |
| { | |
| className: 'right', | |
| points: [ | |
| [-50, -50, +50], | |
| [+50, -50, +50], | |
| [+50, -50, -50], | |
| [-50, -50, -50] | |
| ] | |
| }, | |
| { | |
| className: 'top', | |
| points: [ | |
| [-50, -50, +50], | |
| [-50, +50, +50], | |
| [+50, +50, +50], | |
| [+50, -50, +50] | |
| ] | |
| }, | |
| ]; | |
| } | |
| function axesData() { | |
| return [ | |
| { | |
| label: 'x', | |
| labelLocation: [225, 0, 0], | |
| points: [ | |
| [0, 0, 0], | |
| [200, 0, 0] | |
| ] | |
| }, | |
| { | |
| label: 'y', | |
| labelLocation: [0, 225, 0], | |
| points: [ | |
| [0, 0, 0], | |
| [0, 200, 0] | |
| ] | |
| }, | |
| { | |
| label: 'z', | |
| labelLocation: [0, 0, 225], | |
| points: [ | |
| [0, 0, 0], | |
| [0, 0, 200] | |
| ] | |
| } | |
| ]; | |
| } | |
| function isometricProjection() { | |
| var sin = Math.sin, | |
| cos = Math.cos, | |
| asin = Math.asin, | |
| tan = Math.atan, | |
| PI = Math.PI; | |
| var pitch = PI / 6, | |
| yaw = PI / 4, | |
| alpha = asin(tan(pitch)), | |
| beta = yaw; | |
| // See https://en.wikipedia.org/wiki/Isometric_projection | |
| // TODO: Figure out why ax, ay and az needed to be flipped around. | |
| function project(point) { | |
| var ax = point[1], | |
| ay = -point[2], | |
| az = point[0]; | |
| var x = cos(beta) * ax - sin(beta) * az, | |
| y = cos(alpha) * ay + sin(alpha) * | |
| (sin(beta) * ax + cos(beta) * az); | |
| return [x, y]; | |
| } | |
| project.pitch = function(x) { | |
| if (!arguments.length) return alpha; | |
| pitch = x; | |
| alpha = Math.asin(Math.tan(pitch)); | |
| return project; | |
| }; | |
| project.yaw = function(x) { | |
| if (!arguments.length) return beta; | |
| yaw = x; | |
| beta = yaw; | |
| return project; | |
| }; | |
| return project; | |
| } | |
| function isometricPath() { | |
| var projection = function(d) { return d.slice(0, 2); }; | |
| function path(points) { | |
| return 'M' + | |
| points | |
| .map(function(point) { return projection(point).join(','); }) | |
| .join('L'); | |
| } | |
| path.projection = function(x) { | |
| if (!arguments.length) return projection; | |
| projection = x; | |
| return path; | |
| }; | |
| return path; | |
| } | |
| function radiansToDegrees(radians) { return radians * 180 / Math.PI; } | |
| function degreesToRadians(degrees) { return degrees * Math.PI / 180; } | |
| </script> | |
| </body> | |
| </html> |
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