F# News

A Pythagoras tree is a simple vector graphics image:

The following F# program uses the F# for Visualization library to render this image:

#light

open System.Windows.Media
open FlyingFrog.Graphics

let pi = System.Math.PI

let rotate t = RotateTransform(t / pi * 180.).Value

let branches m =
  [ m * rotate(pi/2. - asin(4. / 5.)) * scale(4. / 5., 4. / 5.) *
      translate(0., 1.);
    m * translate(-1., 0.) * rotate(-pi/2. + asin(3. / 5.)) *
      scale(3. / 5., 3. / 5.) * translate(1., 1.) ]

let line_loop xys = Contour.Closed [ for x, y in xys -> line_to x y ]

let square = line_loop [1., 0.; 1., 1.; 0., 1.; 0., 0.]

let shape brush m =
  Shape([ Interior brush;
          Stroke(Brushes.DarkGreen, { width = 0.01 }) ],
        [ Contour.map (fun p -> p * m) square ])

let trunks brush ms = Group(List.map (shape brush) ms)

let rec tree n ms =
  if n=0 then [trunks Brushes.Green ms] else
    let ms' = List.collect branches ms
    trunks Brushes.BurlyWood ms :: tree (n-1) ms'

do
  let view = View(Group[])
  for n = 1 to 12 do
    view.Scene <- Group(tree n [Matrix.Identity])
  Run()

Download and run the demo!.

Labels: f# for visualization, pythagoras tree, vector graphics

# posted by Jon Harrop @ 21:30