FrankenPhys

Small ammojs-like wrapper around the C++ bullet physics engine

Demo: Sample Test Bed:

https://guillaumebouchetepitech.github.io/FrankenPhys/samples/browser-test-bed/index.html

Features

Small-ish

• FrankenPhys.0.0.1.js -> ~600ko (~60ko after server compression)
• FrankenPhys.0.0.1.wasm -> ~600ko (~250ko after server compression)

Typescript wrapper

• TypeSafety, easy to get started, harder to make mistakes

Memory Safe

• the TypeScript wrapper hide and handle the wasm memory allocations/deallocations
• no wasm memory leaks detected

Support Node.Js and Browser

• A "TypeScript Game Logic" can be reused on both server/client
• Worth checking the /samples folder

Easy to interface with Three.Js

• worth checking the /samples/browser-test-bed folder

Physical Features

• physical world
• rigid bodies
• shapes:
  • box
  • sphere
  • cylinder
  • capsule
  • mesh
  • compound (<- group of sub shapes)
• dynamic vehicles
• 6dof joints v1 (<- 6 degrees of freedom joins)
• 6dof joints v2 (<- twice slower but many times more stable than v1)
• hinges joints (<- this support motor torque)

Contact events

Example at the physic world level:

interface ContactDataWorld {
	contactId: number,
	rigidBodyA: IPhysicBody,
	rigidBodyB: IPhysicBody,
	position: glm.vec3,
	normalB: glm.vec3,
}

physicWorld.addEventListener('beginContact', (event) => {
  console.log('beginContact', event.data.position);
});
physicWorld.addEventListener('updateContact', (event) => {
  console.log('updateContact', event.data.position);
});
physicWorld.addEventListener('endContact', (event) => {
  console.log('endContact', event.data.position);
});
// ccd -> "continuous collision detection"
physicWorld.addEventListener('ccdContact', (event) => {
  console.log('ccdContact', event.data.position);
});

Example at the physic body level:

export interface ContactDataBody {
	contactId: number,
	other: IPhysicBody,
	position: glm.vec3,
	normalB: glm.vec3,
}

physicBody.addEventListener('beginContact', (event) => {
  console.log('beginContact', event.data.position);
});
physicBody.addEventListener('updateContact', (event) => {
  console.log('updateContact', event.data.position);
});
physicBody.addEventListener('endContact', (event) => {
  console.log('endContact', event.data.position);
});
// ccd -> "continuous collision detection"
physicBody.addEventListener('ccdContact', (event) => {
  console.log('ccdContact', event.data.position);
});

Known Issue with Contact events

the contact event are not that reliable on dynamic mesh colliders

CCD (Continuous collision detection)

Useful when shooting "spherical physical bullet"

This prevent the faster "spherical physical bullet" from passing through objects

Example:

// ccd start when going faster than 0.4 units/sec
physicBody.setCcdMotionThreshold(0.4);
// ccd radius sphere is 0.5 units
physicBody.setCcdSweptSphereRadius(0.5);

Missing Features

• Soft Volumes/Bodies -> this save some serious wasm-size/bandwidth