55 lines
1.3 KiB
Text
55 lines
1.3 KiB
Text
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---
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title: Path.angleAt()
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---
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The `Path.angleAt()` method returns the (tangent) angle of a path at a specific point.
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If the given point is a sharp corner, this method prefers returning the angle directly before the corner.
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If the given point does not lie (approximately) on the path, this method returns `false`.
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## Signature
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```js
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number|false path.angleAt(Point point)
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```
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## Example
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<Example caption="Example of the Path.angleAt() method">
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```js
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({ Point, points, Path, paths, snippets, Snippet, part }) => {
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points.A = new Point(45, 60)
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points.B = new Point(10, 30)
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points.BCp2 = new Point(40, 20)
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points.C = new Point(90, 30)
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points.CCp1 = new Point(50, -30)
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points.D = new Point(50, 80)
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points.DCp1 = new Point(70, 30)
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paths.demo = new Path()
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.move(points.D)
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.curve(points.DCp1, points.DCp1, points.C)
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.curve(points.CCp1, points.BCp2, points.B)
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.line(points.A)
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points.testPoint = paths.demo.shiftFractionAlong(0.55)
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snippets.point = new Snippet("notch", points.testPoint)
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let angle = paths.demo.angleAt(points.testPoint)
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//draw a tangent path
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paths.tangent = new Path()
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.move(points.testPoint.shift(angle, -30))
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.line(points.testPoint.shift(angle, 30))
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.attr("class", "lining dashed")
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return part
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}
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```
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</Example>
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## Notes
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Keep in mind that calculations with Bézier curves are often approximations.
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