Ray-casting algorithm: Difference between revisions

=={{header|Scala}}==

From D snippet.

<lang scala>

case class Figure(name: String, edges: ((Double, Double), (Double, Double))*) {}

object Ray_casting extends App {

import Math._

import Double._

val figures = Array(Figure("Square", ((0.0, 0.0), (10.0, 0.0)),

((10.0, 0.0), (10.0, 10.0)), ((10.0, 10.0), (0.0, 10.0)),

((0.0, 10.0), (0.0, 0.0))),

Figure("Square hole", ((0.0, 0.0), (10.0, 0.0)), ((10.0, 0.0), (10.0, 10.0)),

((10.0, 10.0), (0.0, 10.0)), ((0.0, 10.0), (0.0, 0.0)),

((2.5, 2.5), (7.5, 2.5)), ((7.5, 2.5), (7.5, 7.5)),

((7.5, 7.5), (2.5, 7.5)), ((2.5, 7.5), (2.5, 2.5))),

Figure("Strange", ((0.0, 0.0), (2.5, 2.5)), ((2.5, 2.5), (0.0, 10.0)),

((0.0, 10.0), (2.5, 7.5)), ((2.5, 7.5), (7.5, 7.5)),

((7.5, 7.5), (10.0, 10.0)), ((10.0, 10.0), (10.0, 0.0)),

((10.0, 0), (2.5, 2.5))),

Figure("Exagon", ((3.0, 0.0), (7.0, 0.0)), ((7.0, 0.0), (10.0, 5.0)),

((10.0, 5.0), (7.0, 10.0)), ((7.0, 10.0), (3.0, 10.0)),

((3.0, 10.0), (0.0, 5.0)), ((0.0, 5.0), (3.0, 0.0))))

val points = Array((5.0, 5.0), (5.0, 8.0), (-10.0, 5.0), (0.0, 5.0), (10.0, 5.0), (8.0, 5.0), (10.0, 10.0))

figures foreach { f =>

println("Is point inside figure " + f.name + '?')

points foreach { p => println(" " + p + ": " + contains(f, p)) }

println

}

private def raySegI(p: (Double, Double), e: ((Double, Double), (Double, Double))): Boolean = {

val epsilon = 0.00001

if (e._1._2 > e._2._2)

return raySegI(p, (e._2, e._1))

if (p._2 == e._1._2 || p._2 == e._2._2)

return raySegI((p._1, p._2 + epsilon), e)

if (p._2 > e._2._2 || p._2 < e._1._2 || p._1 > max(e._1._1, e._2._1))

return false

if (p._1 < min(e._1._1, e._2._1))

return true

val blue = if (abs(e._1._1 - p._1) > MinValue) (p._2 - e._1._2) / (p._1 - e._1._1) else MaxValue

val red = if (abs(e._1._1 - e._2._1) > MinValue) (e._2._2 - e._1._2) / (e._2._1 - e._1._1) else MaxValue

blue >= red

}

private def contains(f: Figure, p: (Double, Double)) = f.edges.count(raySegI(p, _)) % 2 != 0

}</lang>