DemoProxyProgram01.kt

import org.openrndr.Program
import org.openrndr.application
import org.openrndr.color.ColorRGBa
import org.openrndr.extra.viewbox.viewBox
import org.openrndr.math.Vector2
import kotlin.math.cos

fun Program.program01() {
    var color: ColorRGBa by this.userProperties
    color = ColorRGBa.WHITE

    var someFunction : ()->Unit by this.userProperties
    someFunction = {
        color = ColorRGBa(Math.random(), Math.random(), Math.random())
    }

    extend {
        drawer.fill = color
        drawer.circle(Vector2(width/2.0, height/2.0), cos(seconds) * 50.0 + 50.0)
    }
}

fun main() {
    application {
        program {
            val proxyBox = viewBox(drawer.bounds).apply { program01() }
            var color: ColorRGBa by proxyBox.userProperties
            var someFunction: () -> Unit by proxyBox.userProperties
            color = ColorRGBa.PINK
            extend {
                if (Math.random() < 0.01) {
                    someFunction()
                }
                proxyBox.draw()
            }
        }
    }
}