86 lines
2.5 KiB
Markdown
86 lines
2.5 KiB
Markdown
# orx-triangulation
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An extension for triangulating a set of points using the **Delaunay** triangulation method. From that triangulation we can also derive a **Voronoi** diagram.
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The functionality comes from a Javascript port of the following libraries:
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* [delaunator](https://github.com/ricardomatias/delaunator) (external)
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* [d3-delaunay](https://github.com/d3/d3-delaunay) (the port is included in this package)
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## Usage
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### Delaunay
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The entry point is the `Delaunay` class.
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```kotlin
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val points: List<Vector2>
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val delaunay = Delaunay.from(points)
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// or
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val flatPoints: DoubleArray // (x0, y0, x1, x1, x2, y2)
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val delaunay = Delaunay(flatPoints)
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```
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This is how you retrieve the triangulation results:
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```kotlin
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val triangles: List<Triangle> = delaunay.triangles()
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val halfedges: List<ShapeContour> = delaunay.halfedges()
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val hull: ShapeContour = delaunay.hull()
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// Updates the triangulation after the points have been modified in-place.
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delaunay.update()
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```
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### Voronoi
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The bounds specifices where the Voronoi diagram will be clipped.
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```kotlin
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val bounds: Rectangle
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val delaunay = Delaunay.from(points)
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val voronoi = delaunay.voronoi(bounds)
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// or
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val voronoi = Voronoi(Delaunay.from(points), bounds)
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```
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See [To Infinity and Back Again](https://observablehq.com/@mbostock/to-infinity-and-back-again) for an interactive explanation of Voronoi cell clipping.
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This is how you retrieve th results:
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```kotlin
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val cells: List<ShapeContour> = voronoi.cellsPolygons()
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val cell: ShapeContour = voronoi.cellPolygon(int) // index
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val circumcenters: List<Vector2> = voronoi.circumcenters()
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// Returns true if the cell with the specified index i contains the specified vector
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val contaisVector = voronoi.contains(int, Vector2)
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// Updates the Voronoi diagram and underlying triangulation
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// after the points have been modified in-place
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voronoi.update()
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```
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### Author
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Ricardo Matias / [@ricardomatias](https://github.com/ricardomatias)
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<!-- __demos__ -->
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## Demos
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### DemoDelaunay01
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[source code](src/demo/kotlin/DemoDelaunay01.kt)
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### DemoDelaunay02
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[source code](src/demo/kotlin/DemoDelaunay02.kt)
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### DemoVoronoi01
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[source code](src/demo/kotlin/DemoVoronoi01.kt)
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