haxebullet.md

HaxeBullet

Bullet Physics

One of current Armory supported Physics Engine is through Bullet Physics with HaxeBullet

Please note, as at time of this written, HaxeBullet still does not support all of native C++ Bullet Physics implementation. Contribution is welcome!

Javascript backend for Krom/other Javascript deployments is based on Ammo. Ammo supported Bullet API can be found in this API Reference

C++ backend for native C++ compile is based on native Bullet Physics C++. Native implementation API docs can be found in this API Reference

For any HaxeBullet implementation, it is recommended to support APIs that are supported by both Ammo/native C++ Bullet codes to not run into different behavior on different platforms.

Update HaxeBullet

• Install Git
• Click the Fork button on GitHub
• Pick a location, open a command line here and clone your forked repository

git clone https://github.com/my_username/haxebullet

• Apply your changes, then open a command line in your forked repository and push the changes

git add .
git commit -m "My haxebullet patch description"
git push origin master

• Create pull request by clicking compare across forks and selecting your fork

• Thanks for contributing!

Local Armory setup

When working on HaxeBullet patches, it is useful to setup the Armory3D locally and apply your modification in following folders:

/armsdk_path/armsdk/lib/haxebullet

Following is the Javascript backend implementation

/armsdk_path/armsdk/lib/js/ammo

Following is the C++ backend implementation

/armsdk_path/armsdk/lib/cpp/bullet

Following is the haxe API implementation

/armsdk_path/armsdk/lib/cpp/Sources/haxebullet/Bullet.hx

Note [1]: Disable Armory Project - Cache Compiler to always recompile the project when you hit Play. There is no need to compile Armory itself, you will see the changes in action instantly.

Note [2]: If do not want to recompile every time, one can also use use the Clean button next to Play to manually clean up the project when needed

Note [3]: It is especially important to clean up the project for any Javascripts/relate changes as the project will likely to cache these files, failure to do so may result changes not showing up

Example Update

For example, need to add support for following

BtWheelInfo.m_deltaRotation

Confirm both native Bullet Physics C++. Native implementation API docs can be found in this API Reference and API Reference supported it

Update following in the Armory SDK

/armsdk_path/armsdk/lib/cpp/Sources/haxebullet/Bullet.hx

extern class BtWheelInfo {
	#if js
	public function new(ci:BtWheelInfoConstructionInfo):Void;
	public static inline function create(ci:BtWheelInfoConstructionInfo):BtWheelInfo {
		return new BtWheelInfo(ci);
	}
	#elseif cpp
	@:native("btWheelInfo")
	public static function create(ci:BtWheelInfoConstructionInfo):BtWheelInfo;
	#end

    ...
	public var m_deltaRotation:BtScalar;
	
	...

Test the change in vehicle template (with project cache clean at least once after the change)

The new change should show up

If there is problem like above API

/armsdk_path/armsdk/lib/cpp/Sources/haxebullet/Bullet.hx

returns null, it is likely the backend support is not ready

If there is problem with HaxeBullet implementation, it should error out at compile time with api is not found error