Create CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,83 @@
+# Contributing to ORX
+
+Thank you for your interest in contributing to ORX :-)
+
+This repository contains the OPENRNDR extras: a growing library of assorted data structures, algorithms and utilities to complement OPENRNDR.
+Other repositories you can contribute to are the [core OPENRNDR](https://github.com/openrndr/openrndr/), 
+the [guide](https://github.com/openrndr/openrndr-guide/) and the [template](https://github.com/openrndr/openrndr-template/).
+
+Please read the [general information about contributing to OPENRNDR](https://github.com/openrndr/openrndr/blob/master/CONTRIBUTING.md).
+This document will focus on specific details about the ORX repository.
+
+## Overview
+
+There are two types of ORX extras: 
+- JVM only. Subfolders of `/orx-jvm/`. These run only on Desktop (not in web browsers).
+- Multiplatform. Other `/orx-.../` folders. These run both on Desktop and web browsers.
+
+Each orx folder contains a `README.md`, a `build.gradle.kts` file and a `src` folder. 
+Please explore several orx directories to get a feel for how they look like.
+
+Various Gradle tasks take care of updating the README files. 
+
+## README.md
+
+Assuming you are creating an orx called `magic`, the readme file should contain the following:
+
+```
+# orx-magic
+
+One or more lines including a short description to display on the root README.md.
+One or more lines including a short description to display on the root README.md.
+One or more lines including a short description to display on the root README.md.
+
+[Main content describing the usage of orx-magic goes here]
+
+<!-- __demos__ -->
+```
+
+1. Start with a markdown header with the name of the orx followed by an empty line.
+2. One or more lines with a brief description to show on the root `README.md`, followed by an empty line.
+   (The `buildMainReadme` Gradle task will extract this description and update the root `README.md`).
+3. A detailed description (a guide) of how to use the orx, possibly with code examples in code fences like
+   ````
+   ```kotlin
+     //code example
+   ```
+   ````
+4. If the orx includes demos (more below), running the `CollectScreenShots` Gradle task will append `<!-- __demos__ -->`
+   to the readme followed by a list of automatically generated screenshots of the demos and links to their source code.
+   This is specially useful for orx'es that produce graphical output, but less so for orx'es that interface
+   with hardware (like `orx-midi`).
+
+## build.gradle.kts
+
+ORX `build.gradle.kts` files declare their dependencies and most follow the same structure. 
+Please explore various build files and find the simplest one that matches your use case. 
+Note that the JVM ones are somewhat simpler than the multiplatform ones.
+
+The `plugins` section includes either ``org.openrndr.extra.convention.`kotlin-multiplatform` `` or
+``org.openrndr.extra.convention.`kotlin-jvm` `` depending on the orx type.
+
+### JVM
+
+The JVM build files declare separate dependencies for the orx itself (`implementation`) and for usage demos
+(`demoImplementation`). 
+See an [example](https://github.com/openrndr/orx/blob/master/orx-jvm/orx-dnk3/build.gradle.kts).
+
+### Multiplatform
+
+The multiplatform build files can have 4 blocks: `commonMain`, `commonTest`, `jvmTest` and `jvmDemo`. 
+See an [example](https://github.com/openrndr/orx/blob/master/orx-color/build.gradle.kts).
+
+## Source folder
+
+To do.
+
+## Demos
+
+To do.
+
+## Gradle tasks
+
+To do.