added build instructions, close #2839

BUILDING.md

@@ -0,0 +1,38 @@
+# Building
+## Pre-requisites
+- A bash shell (git bash is sufficient for Windows)
+- [`git`](https://git-scm.com) available in your shell
+- PHP 7.2 or newer available in your shell
+- [`composer`](https://getcomposer.org) available in your shell
+
+## Custom PHP binaries
+Because PocketMine-MP requires several non-standard PHP extensions and configuration, PMMP provides scripts to build custom binaries for running PocketMine-MP, as well as prebuilt binaries.
+
+- [Prebuilt binaries](https://jenkins.pmmp.io/job/PHP-7.3-Aggregate)
+- [Compile scripts](https://github.com/pmmp/php-build-scripts) are provided as a submodule in the path `build/php`
+
+If you use a custom binary, you'll need to replace `composer` usages in this guide with `path/to/your/php path/to/your/composer.phar`.
+
+## Setting up environment
+1. `git clone --recursive https://github.com/pmmp/PocketMine-MP.git`
+2. `composer install`
+
+## Checking out a different branch to build
+1. `git checkout <branch to checkout>`
+2. `git submodule update --init`
+3. Re-run `composer install` to synchronize dependencies.
+
+## Optimizing for release builds
+1. Add the flags `--no-dev --classmap-authoritative` to your `composer install` command. This will reduce build size and improve autoloading speed.
+2. Preprocess the source code by running `build/preprocessor/PreProcessor.php`. Usage instructions are provided in `build/php/README.md`.
+
+### Note
+Preprocessor requires that the `cpp` (c preprocessor) is available in your PATH.
+
+## Building `PocketMine-MP.phar`
+Run `build/server.phar` using your preferred PHP binary. It'll drop a `PocketMine-MP.phar` into the current working directory.
+
+You can also use the `--out` option to change the output filename.
+
+## Running PocketMine-MP from source code
+Run `src/pocketmine/PocketMine.php` using your preferred PHP binary.

README.md

@@ -17,6 +17,7 @@
 - [StackOverflow](https://stackoverflow.com/tags/pocketmine)
 
 ## For developers
+ * [Building and running from source](BUILDING.md)
  * [Latest API documentation](https://jenkins.pmmp.io/job/PocketMine-MP-doc/doxygen/) - Doxygen documentation generated from development
  * [DevTools](https://github.com/pmmp/PocketMine-DevTools/) - Development tools plugin for creating plugins
  * [ExamplePlugin](https://github.com/pmmp/ExamplePlugin/) - Example plugin demonstrating some basic API features