Geometry

Playing around with Kotlin and computational geometry algorithms.

How to add

Use this Gradle dependency or Maven equivalent:

repositories {
    ...
    maven { url "https://jitpack.io" }
}

dependencies {
    // choose the modules you need:
    compile 'com.github.h0tk3y.geometry:geometry:v0.1'
    compile 'com.github.h0tk3y.geometry:algorithms:v0.1'
    compile 'com.github.h0tk3y.geometry:visualizer:v0.1'
    compile 'com.github.h0tk3y.geometry:demos:v0.1'
    
    // or, to add all the above:
    compile 'com.github.h0tk3y:geometry:v0.1'
}

Algorithms implemented at the moment

• Convex hull

  • Jarvis algorithm
  • Graham algorithm
  • Andrew algorithm
  • Quickhull

• Polygon triangulation

  • Ear clipping algorithm

• Segments intersection

  • Bentley-Ottmann algorithm

• Minkowski addition for convex shapes

Geometry primitives like left turn predicate and distance are also there.

Visualizer

Zoom, moving, left click, right-click and drag callbacks are implemented. Moving is done with right mouse button drag, zooming -- with mouse scroll.

How to include one into your app:

parent as JPanel

val v = Visualizer()
parent.add(v)

That's it!

Or even simpler, there's Demo app stub which you can use:

val demo = Demo()
val v = demo.visualizer()
demo.start()

See the demos attached for more examples.

How to use:

v as Visualizer

v.add(PointDrawable(0.5, 0.5))
v.add(PointDrawable(0.1, 0.3, Color.GREEN))
v.add(SegmentDrawable(0.1, 0.3, 0.5, 0.5))

v.area = Area(0.1, 0.1, 0.9, 0.9)

v.add((0..100).map { SegmentDrawable(0.0, it * 0.01, 1.0, it * 0.01 })
v.remove({ it is PointDrawable })

v.onClick { x, y ->
    println("Clicked at $x, $y.")
    v.add(PointDrawable(x, y, someRandomColor()))
}

v.onDrag { x0, y0, x1, y1 ->
    val p0 = Point(x0, y0)
    val p1 = Point(x1, y1)
    if (distance(p0, p1) >= 0.3) {
        println("Dragged so long! From $x0, $y0 to $x1, $y1.")
        v.add(SegmentDrawable(p0, p1))
    }
}