physxhx

Haxe/hxcpp @:native bindings for PhysX.

This is a linc & Kha library.

---

This library works with the Haxe cpp target only.

---

Notes

This library was written with the following in mind:

• Write bindings in a way that allow natural Haxe expressions.
  • e.g. Using new ExternClass instead of ExternClass.create wherever possible & sensible.
  • As well as operator overloads for mathematical structures such as PxVec3 and PxQuat.
• Maintain original physx folder layout and documentation wherever possible & sensible.
  • To aid in development and not have to keep the docs open all the time.
• To do this we have to write the bindings manually.

Other features include:

• Callbacks implemented as a base class in Haxe to extend, to write the behavior in Haxe.
  • The class names are typically postfixed with Hx.
  • E.g. PxSimulationEventCallback => PxSimulationEventCallbackHx:

    class SimulationCallback extends PxSimulationEventCallbackHx
    {
        public function new() { super(); }
        override function onContact(pairHeader:PxContactPairHeader, pairs:haxe.ds.Vector<PxContactPair>)
        {
            // do stuff...
        }
    }

• PxUserData as a helpful facilitation for void* userData between Haxe and C++.
  • Convenience for pointing to haxe object, or reinterpreting void* as int or const char*:

    var anyObj:String = "stringObj";
    actor.userData = anyObj; // stores pointer to anyObj
    var str:String = actor.userData; // get what userData points to, as a String
    anyObj = "changedString";
    trace(x); // prints stringObj
    trace((actor.userData:String)); // prints changedString
    
    var anyObj:Int = 123;
    actor.userData.rawInt = anyObj; // store 123 in userData. This simply treats the void* as int
    anyObj = 456;
    trace(actor.userData.rawInt); // still prints 123.
    
    actor.userData.stringLiteral = "Player"; // store "Player" as a const char*
    trace(actor.userData.stringLiteral); // prints Player
    
    actor.userData.stringLiteral = str; // not recommended. Stores internal data of str, which may get GC'ed and data overwritten
    str = "modifiedString";
    trace(actor.userData.stringLiteral); // still prints stringObj

• Multithreading (asynchronous simulation etc.) in PxDefaultCpuDispatcher implemented for hxcpp.
  • For foreign threads to cooperate with Haxe, we have to attach/detach to/from Haxe GC.
  • See modification of ExtCpuWorkerThread => ExtCpuWorkerThreadHx.

Usage

See test/Main.hx. Build with build.hxml with cwd in test/.

Install PhysX Visual Debugger. Run the PVD, then run the test and it should automatically connect to the PVD.

Also see the PhysX 4.1 User Guide and PhysX 4.1 API Documentation.

Using for Kha

To use physxhx as a Kha library, simply add the library and dlls (which need to exist beside the output exe), by adding to your khafile.js:

if(platform == Platform.Windows)
{
    let dir = project.addLibrary('physxhx');
    project.addAssets(dir + '/lib/Windows/dll/**', { destination: '', notinlist: true });
}

Example Code

The following code is adapted from SnippetHelloWorld.cpp:

class Main
{
    static public function main()
    {
        var test:Test = new Test();
        test.initPhysics();
        for(i in 0...100)
            test.stepPhysics();
        test.cleanupPhysics();
    }
}

class Test
{
    var gFoundation:PxFoundation;
    var gPhysics:PxPhysics;
    var gPvd:PxPvd;
    var gMaterial:PxMaterial;
    var gScene:PxScene;
    var gDispatcher:PxDefaultCpuDispatcher;
    static var gErrorCallback:PxDefaultErrorCallback = null;
    static var gAllocator:PxDefaultAllocator = null;

    public function new() {}

    function createDynamic(t:PxTransform, geometry:PxGeometry, velocity:PxVec3):PxRigidDynamic
    {
        var dyn = PxSimpleFactory.createDynamic(gPhysics, t, geometry, gMaterial, 10);
        dyn.setAngularDamping(0.5);
        dyn.setLinearVelocity(velocity);
        gScene.addActor(dyn);
        return dyn;
    }

    function createStack(t:PxTransform, size:PxU32, halfExtent:PxReal)
    {
        var shape = gPhysics.createShape(PxBoxGeometry.create(halfExtent, halfExtent, halfExtent), gMaterial);
        for(i in 0...size)
        {
            for(j in 0...size-i)
            {
                var localTm = new PxTransform(new PxVec3(j * 2 - (size - i), i * 2 + 1, 0) * halfExtent, PxQuat.identity());
                var body = gPhysics.createRigidDynamic(t.transform(localTm));
                body.attachShape(shape);
                PxRigidBodyExt.updateMassAndInertia(body, 10);
                gScene.addActor(body);
            }
        }
        shape.release();
    }

    public function initPhysics()
    {
        gFoundation = PxFoundation.create(PX_PHYSICS_VERSION, gAllocator, gErrorCallback);

        gPvd = PxPvd.create(gFoundation);
        var transport = PxPvdTransport.defaultPvdSocketTransportCreate("127.0.0.1", 5425, 10);
        gPvd.connect(transport, eALL);
    
        gPhysics = PxPhysics.create(PX_PHYSICS_VERSION, gFoundation, new PxTolerancesScale(), true, gPvd);
    
        var sceneDesc = new PxSceneDesc(gPhysics.getTolerancesScale());
        sceneDesc.gravity = new PxVec3(0, -9.81, 0);

        gDispatcher = PxDefaultCpuDispatcher.create(4);
        sceneDesc.cpuDispatcher	= gDispatcher;
        sceneDesc.filterShader = PxDefaultSimulationFilterShader.func;
        
        gScene = gPhysics.createScene(sceneDesc);
    
        var pvdClient = gScene.getScenePvdClient();
        if(pvdClient != null)
        {
            pvdClient.setScenePvdFlag(eTRANSMIT_CONSTRAINTS, true);
            pvdClient.setScenePvdFlag(eTRANSMIT_CONTACTS, true);
            pvdClient.setScenePvdFlag(eTRANSMIT_SCENEQUERIES, true);
        }
        gMaterial = gPhysics.createMaterial(0.5, 0.5, 0.6);

        var groundPlane = PxSimpleFactory.createPlane(gPhysics, new PxPlane(0, 1, 0, 0), gMaterial);
        gScene.addActor(groundPlane);
        
        var stackZ = 10.0;
        for(i in 0...5)
        {
            stackZ -= 10.0;
            createStack(new PxTransform(new PxVec3(0, 0, stackZ), PxQuat.identity()), 10, 2.0);
        }
        
        createDynamic(new PxTransform(new PxVec3(0,40,100), PxQuat.identity()), new PxSphereGeometry(10), new PxVec3(0,-50,-100));
    }

    public function stepPhysics()
    {
        gScene.simulate(1.0 / 60.0);
        gScene.fetchResults(true);
    }

    public function cleanupPhysics()
    {
        gScene.release();
        gDispatcher.release();
        gPhysics.release();
        if(gPvd != null)
        {
            var transport = gPvd.getTransport();
            gPvd.release();
            transport.release();
        }
        gFoundation.release();
    }
}

Precompiled libs and dlls

Currently there are only Windows libs and dlls included. They are compiled on a Windows x64 machine, in Visual Studio 2019.

As per build guidelines they are compiled with the checked build configuration which is recommended for day-to-day development and QA. If you need other build configs (e.g. release), please build them yourself. See the linked page for a guide.

Contributions

Please note that this is my first hxcpp binding project, as well as my first time using PhysX. Therefore there may be things I've mishandled and not taken into account. Furthermore, PhysX is a gigantic project to bind and so there are bound to be many things not done. Still, I hope I've covered the bases. That said, contributions and PRs are highly welcome!

Alternatives

physxhx was written for a still very wip 3d engine I've been working on.

Alternatives for 3d physics:

• OimoPhysics
• haxebullet

License

The Haxe code is licensed under the MIT License. The headers and minor source modifications still have the original license intact.