Modification of d3.curveStepBefore to round the corners. Code up for this stackoverflow question.
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September 26, 2023 09:33
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d3-shape Custom Curve Implementation
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| license: mit |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <script data-require="d3@4.0.0" data-semver="4.0.0" src="https://d3js.org/d3.v4.min.js"></script> | |
| <script src="roundStep.js"></script> | |
| </head> | |
| <body> | |
| <script> | |
| var width = 900, | |
| height = 500, | |
| N = 10; | |
| var svg = d3.select('body') | |
| .append('svg') | |
| .attr('width', width) | |
| .attr('height', height); | |
| var points = []; | |
| for (var i = 0; i < N; i++) { | |
| points.push({ | |
| x: (width / N) * i + (width / N / 2), | |
| y: Math.random() * height | |
| }); | |
| } | |
| var line1 = d3.line() | |
| .x(function(d) { | |
| return d.x; | |
| }) | |
| .y(function(d) { | |
| return d.y; | |
| }) | |
| .curve(stepRound); | |
| var line2 = d3.line() | |
| .x(function(d) { | |
| return d.x; | |
| }) | |
| .y(function(d) { | |
| return d.y; | |
| }) | |
| .curve(d3.curveStepBefore); | |
| svg.append('path') | |
| .datum(points) | |
| .attr('d', line1) | |
| .attr('fill', 'none') | |
| .attr('stroke', 'orange') | |
| .attr('stroke-width', '4px'); | |
| svg.append('path') | |
| .datum(points) | |
| .attr('d', line2) | |
| .attr('fill', 'none') | |
| .attr('stroke', 'steelblue') | |
| .attr('stroke-width', '1px'); | |
| </script> | |
| </body> | |
| </html> |
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| function Step(context) { | |
| this._context = context; | |
| this._t = 0; | |
| } | |
| Step.prototype = { | |
| areaStart: function() { | |
| this._line = 0; | |
| }, | |
| areaEnd: function() { | |
| this._line = NaN; | |
| }, | |
| lineStart: function() { | |
| this._x = this._y = NaN; | |
| this._point = 0; | |
| }, | |
| lineEnd: function() { | |
| if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath(); | |
| if (this._line >= 0) this._t = 1 - this._t, this._line = 1 - this._line; | |
| }, | |
| point: function(x, y) { | |
| x = +x, y = +y; | |
| switch (this._point) { | |
| case 0: { | |
| this._point = 1; | |
| this._context.moveTo(x, y); | |
| break; | |
| } | |
| case 1: this._point = 2; // proceed | |
| default: { | |
| if (this._t <= 0) { | |
| console.log(this._y) | |
| var xN = Math.abs(x - this._x) * 0.25, | |
| yN = Math.abs(y - this._y) * 0.25, | |
| mYb = (this._y < y) ? this._y + yN : this._y - yN, | |
| mYa = (this._y > y) ? y + yN : y - yN; | |
| this._context.quadraticCurveTo(this._x, this._y, this._x, mYb); | |
| this._context.lineTo(this._x, mYa); | |
| this._context.quadraticCurveTo(this._x, y, this._x + xN, y); | |
| this._context.lineTo(x-xN, y); | |
| //this._context.quadraticCurveTo(x, y, x, mY); | |
| } else { | |
| var x1 = this._x * (1 - this._t) + x * this._t; | |
| this._context.moveTo(x1, this._y); | |
| this._context.lineTo(x1, y); | |
| } | |
| break; | |
| } | |
| } | |
| this._x = x, this._y = y; | |
| } | |
| }; | |
| stepRound = function(context) { | |
| return new Step(context); | |
| } |
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