Hi there, I just tried running a Processing program written in the Kotlin language, and I thought I would share here the steps in case anyone wants to try. This may not be very interesting if you are happy using the Processing IDE and your projects don’t grow very large. I wonder how many users in this forum use other editors like IntelliJ Idea… If you already do then you might be curious about trying this: Install IntelliJ Idea community edition (free), Processing and Kotlin. Create a new Kotlin/JVM project Go to Project Structure and add the processing/core/library/ folder to Libraries Create a new Kotlin file inside src/: Main.kt (or whatever you want to call it) Paste this example which is a slightly modified version of code by Donnie Flood import processing.core.PApplet import processing.core.PConstants data class Circle(val radius: Float, val x: Float, val y: Float, var color: Int = 0) class CirclePacking : PApplet() { companion object Factory { fun run() { var art = CirclePacking() art.setSize(500, 500) art.runSketch() } } private val circleSizeCounts = listOf( 65 to 19, 37 to 38, 20 to 75, 7 to 150, 3 to 300 ) private fun randomXY(xMin: Float, xMax: Float, yMin: Float, yMax: Float): Pair { return Pair(random(xMin, xMax), random(yMin, yMax)) } override fun setup() { colorMode(PConstants.HSB, 360f, 100f, 100f, 1.0f) noStroke() background(70) val allCircles = mutableListOf () for (circleSizeCount in circleSizeCounts) { val circleSize = circleSizeCount.first val circleCount = circleSizeCount.second for (i in 1..circleCount) { // allow up to 100 collisions for (c in 0..1000) { // generate random point // do not allow circles to overlap canvas // val (x, y) = randomXY(0f+circleSize, 500f-circleSize, 0f+circleSize, 500f-circleSize); // allow circles overlapping canvas val (x, y) = randomXY(0f, width.toFloat(), 0f, height.toFloat()); val testCircle = Circle(circleSize.toFloat(), x, y) if (!circleOverlaps(allCircles, testCircle)) { // get random color val c = weightedChoice( listOf( floatArrayOf(0f, 0f, random(90f, 100f)) to 0.6f, floatArrayOf(random(180f, 220f), 50f, 50f) to 0.3f, floatArrayOf(random(0f, 20f), 80f, 80f) to 0.1f ) ) testCircle.color = color(c[0], c[1], c[2]) allCircles.add(testCircle) break } } } } for (circle in allCircles) { fill(circle.color) ellipse(circle.x, circle.y, circle.radius * 2, circle.radius * 2) } } override fun draw() { } private fun circleOverlaps(allCircles: List , testCircle: Circle): Boolean { return allCircles.asSequence().any { val distance = dist(it.x, it.y, testCircle.x, testCircle.y) distance >): FloatArray { val weightSum = colorsAndWeights.sumBy { (it.second * 100).toInt() } if (weightSum != 100) throw AssertionError("Weights should sum to 1") val random = random(0f, 1.0f) var weightTotal = 0f for (i in colorsAndWeights) { if (random >= weightTotal && random ) { CirclePacking.run() } Right click on the Main.kt file on the left and choose Run (green triangle icon). If everything is set up properly, the program should start after a few seconds. [2018-09-29-183250_500x500_scrot] In the code above you can see some similarities with a Java Processing program (import, class, PApplet, private, override) and some differences (var, val, listOf, no semicolons, types after and not before). I do like how Kotlin code looks like. I’m concerned about it being young, and that it’s sponsored and developed by one company. On the other hand, it’s very active (multiple releases per day), has many contributors and many Android developers have switched to it. The only mention to the word Kotlin in this forum was by @cansik in his presentation. What’s your experience with it @cansik? Has anyone else tried working with Kotlin? What are your thoughts on using this language for creative coding? Any advantages or disadvantages on using it? Is the effort of learning one more language worth it?

Sure but that wasn’t the question :slight_smile: Apparently in Kotlin you can add methods to any class directly from your code.

[image] hamoid: Apparently in Kotlin you can add methods to any class directly from your code. Even Java itself can add new methods (even new fields and constructors too) to a class via subclassing w/ extends. There’s also anonymous instantiation. Which customizes an individual object creation just like a subclass.

Kotlin, similar to C# and Gosu, provides the ability to extend a class with new functionality without having to inherit from the class or use any type of design pattern such as Decorator. This is done via special declarations called extensions . Kotlin supports extension functions and extension properties . See https://kotlinlang.org/docs/reference/extensions.html

Now I’ve got it! You want to edit classes in such a way that all past & future instances of them have new members, right? :thinking: Indeed Java can’t do that! Creating a custom subclass doesn’t replace the original. :disappointed: Nor does it force other places instantiating the original class to use our own “hacked” version. Even less can it upgrade already existing object instances. :sob: 1st languages that come to mind which can easily edit classes & objects on-the-fly are JavaScript & Lua. :first_quarter_moon_with_face: Lua I barely know anything about it. But in JS we merely append new properties on a constructor’s prototype{} object. :money_mouth_face: After that, all object instances of that constructor immediately receive those new added properties. :partying_face: Here’s an example sketch that adds a new method called zero() to the p5js’ p5.Vector class: :zero: function setup() { noCanvas(); const vec = p5.Vector.random3D(); print(vec); print(`Method zero() exists in PVector: ${'zero' in vec}\n`); p5.Vector.prototype.zero = function () { this.x = this.y = this.z = 0; return this; }; vec.zero(); print(vec); print('Method zero() exists in PVector: ' + ('zero' in vec)); } Just copy & paste the sketch above on OpenProcessing.org in order to run it btW: :wink: www.OpenProcessing.org/sketch/create Of course there are many more other languages which can edit classes & objects on-the-fly as well. :airplane: And among those, Python of course: :snake: vec = PVector.random3D(this) print vec print 'Method zero() exists in PVector: %s\n' % hasattr(vec, 'zero') def zero(v): v.x = v.y = v.z = 0 return v setattr(PVector, zero.__name__, zero) vec.zero() print vec print 'Method zero() exists in PVector: ' + `hasattr(vec, 'zero')` exit()

Hi @hamoid Yes I am using Kotlin as main language for my processing projects. I really love the syntactic sugar it offers (extension methods, optional parameters, type inference …) and the null-safety, coroutines, a simpler functional interface for lists (more like LINQ from C#) and much more. But I mainly use it for larger projects, where I need a good software architecture. You can find some of my projects here: led-forest3 - very adaptive interactive installation realsense-processing - smaller sketch as a proof of concept anna - based on led-forest3 but another installation (then one of my presentation) Extension methods are a great too to polish an API which adds too much clutter to your code. For example, I use the following method a lot which gives you the security that you won’t ever forget the endDraw(): fun PGraphics.draw(block: (g: PGraphics) -> Unit) { this.beginDraw() block(this) this.endDraw() } And you find many more here: Extensions.kt PVectorExtension.kt But really the most interesting part of kotlin is, that you do not use nullable types. So usually you can be sure that no variable is null. That leads to another way of how you write your code. Mostly processing uses the nullability, so sometimes you have to work around a bit. For me kotlin is not “better” or “faster” then java, just more fun to use and in some ways helps me to write cleaner code.

Thank you @cansik for posting your code! Very useful to learn this new approach :slight_smile: Question: I’m trying to inherit from PGraphics3D but apparently when I call LCircle.draw() the PGraphics has not been initialized (NPE at clear()). Any ideas? package com.hamoid import processing.core.PApplet import processing.core.PConstants class Basic : PApplet() { lateinit var layer : LCircle companion object Factory { fun run() { val art = Basic() //art.setSize(700, 500) art.runSketch() } } override fun settings() { size(700, 500, PConstants.P3D) } override fun setup() { background(70.0f, 20.0f, 200.0f) layer = LCircle(this, 500, 500) } override fun draw() { line(0.0f, 0.0f, width * 1.0f, height * 1.0f); layer.draw() } } fun main() { Basic.run() } This is an example “hello world” layer: package com.hamoid import processing.core.PApplet import processing.opengl.PGraphics3D class LCircle(p5: PApplet, w: Int, h: Int) : PGraphics3D() { init { setParent(p5) setPrimary(false) setSize(w, h) } fun draw() { clear() fill(255) circle(width* 0.5f, height * 0.5f, 100.0f) } } Update: the thing that was missing was a beginDraw() / endDraw() inside fun draw(). The clean syntax (without the myPG. prefix) made me forget I was inside a PGraphics.

There is also Sam Pottingers fork works great for me:- [lambda]

Thanks! Yes, been keeping an eye on it. Although Processing core generally works fine with OpenJDK 11 as is. Was about to ship PraxisLIVE v4.3 with Java 11 but having some testing issues with crashes when closing windows on macOS. This is a bug in JOGL unfortunately so will still be there in Sam’s fork.

Is it even possible to initialise a valid PGraphics without using the createGraphics(width, height) method? I have never inherited from PGraphics3D, I always decorate it.

Ah yes, I found the solution. I added it to my question :slight_smile: It works :slight_smile: ps. I found it thanks to the source code linked by @neilcsmith at Is it possible to extend the classes PGraphics/ PGraphics3D?

Writing Processing in Kotlin

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Writing Processing in Kotlin

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