Maybe draw equilateral triangles, rather than isosceles ones, in Sierpinski.scala

[philipschwarz]

Hello. I love this Sierpinski function: it makes for a great example of recursion. I hit upon this Doodle version as I worked on https://www.slideshare.net/pjschwarz/sierpinski-triangle-polyglot-fp-for-fun-and-profit-haskell-and-scala-with-minor-corrections.

I have a small suggestion to make: see the comment I left in the code.

Of course if you are at all interested in making any change, you will do it yourself, but FWIW, here could be one way to do it: https://www.slideshare.net/pjschwarz/sierpinski-triangle-polyglot-fp-for-fun-and-profit-haskell-and-scala-with-minor-corrections#49:

  object EquilateralTriangle:
    // From https://en.wikipedia.org/wiki/Square_root_of_3:
    // The square root of 3 ...is also known as Theodorus' constant,
    // after Theodorus of Cyrene, who proved its irrationality.
    private val constantOfTheodorus: Double = Math.sqrt(3)

    // From https://en.wikipedia.org/wiki/Equilateral_triangle:
    // The altitude (height) h from any side a is √3÷2×a
    private val widthToHeightMultiplier = constantOfTheodorus / 2

    def heightFromWidth(width: Double): Double =
      widthToHeightMultiplier * width

Image.triangle(width = size, height = EquilateralTriangle.heightFromWidth(size))

[philipschwarz]

Here are three examples of the effect, on the Sierpinski triangle, of switching from isosceles triangles to equilateral ones:

[noelwelsh]

Good suggestion. I've added an equilateral triangle element to the various parts of Doodle that need it.

[philipschwarz]

@noelwelsh great - thanks!