/*
 * file: Sierpinski.kt
 * date: 2019-06-23
 * @author: SS
 */
 
/**
 * Starting from n = 1, this program loops forever displaying
 * the level-n Sierpinski triangle, waits for the user to hit
 * any key, then displays the level-((n+1)%8) Sierpinski triangle,
 * and waits for a key hit by the user, and so on, ad infinitum.
 */
import processing.core.PApplet
import kotlin.math.*

fun main(args: Array<String>) {
    PApplet.main("SierpinskiSketch");
}

class SierpinskiSketch : PApplet() {
    var level = 0

    override fun settings() {
        fullScreen()
        noLoop()
    }

    override fun draw() {
        background(250F)
        val len = 0.8F * min(width, height)
        sierpinski((width-len)/2F, len, len, ++level)
        level %= 8
    }

    override fun keyPressed() {
        redraw()
    }

    fun sierpinski(x: Float, y: Float, len: Float, n: Int) {
        if (n < 1) return
        if (n == 1) {
            fill(0)
            triangle(x, y, x+len, y, x+len/2F, y-sqrt(3F)*len/2F)
            fill(255)
        } else {
            sierpinski(x, y, len/2F, n-1)
            sierpinski(x+len/2F, y, len/2F, n-1)
            sierpinski(x+len/4F, y-sqrt(3F)*len/4F, len/2F, n-1)
        }
    }
}