API

Forces

How to use it

Both forces and impulses don't have any effect on bodies whose mass is 0.

body.applyForce(
    new BABYLON.Vector3(0, 10, 0), // direction and magnitude of the applied force
    new BABYLON.Vector3(0, 0, 0) // point in WORLD space where the force will be applied    
);


// .... OR .....


body.applyImpulse(
    new BABYLON.Vector3(0, 10, 0), // direction and magnitude of the applied impulse
    new BABYLON.Vector3(0, 0, 0) // point in WORLD space where the impulse will be applied    
);

A reminder that, if a body's transform node contains Thin Instances, you can choose which instance to apply the force/impulse by passing instanceIndex as a parameter:

// Apply a force to the first instance ONLY
body.applyForce(new BABYLON.Vector3(100, 0, 0), new BABYLON.Vector3(0, 0, 0), 0);

If no index is applied, the force/impulse is applied to all instances.

Difference between a force and an impulse

A force is a continuous effect that is applied to an object over time, which can change the object's velocity or direction of motion. For example, a force could be used to simulate gravity, wind resistance, or a player pushing an object.

An impulse, on the other hand, is a sudden, instantaneous effect that changes the velocity of an object. It is a specific amount of force applied over a very short duration of time, often modeled as a single frame in a game. For example, a collision between two objects might generate an impulse that changes the direction and speed of both objects.

In summary, a force is a continuous effect over time, while an impulse is a sudden, instantaneous effect that changes the velocity of an object. Click on the sphere in the following examples to experiment with forces and impulses

applyForce applyImpulse

Physics Helper

The helper assists you with creating some phenomena like radial explosions or vortices.

var physicsHelper = new BABYLON.PhysicsHelper(scene);


var origin = BABYLON.Vector3(0, 0, 0);
var radius = 10;
var strength = 20;
var falloff = BABYLON.PhysicsRadialImpulseFalloff.Linear; // or BABYLON.PhysicsRadialImpulseFalloff.Constant


var explosionEvent = physicsHelper.applyRadialExplosionImpulse( // or .applyRadialExplosionForce
    origin,
    radius,
    strength,
    falloff
);
// the second `radius` argument can also act as options: `.applyRadialExplosionImpulse(origin, { radius: radius, strength: strength, falloff: falloff })`


// or


var gravitationalFieldEvent = physicsHelper.gravitationalField(
    origin,
    radius,
    strength,
    falloff
);
// the second `radius` argument can also act as options: `.gravitationalField(origin, { radius: radius, strength: strength, falloff: falloff })`
gravitationalFieldEvent.enable(); // need to call, if you want to activate the gravitational field.
setTimeout(() => gravitationalFieldEvent.disable(), 3000);


// or


var updraftEvent = physicsHelper.updraft(
    origin,
    radius,
    strength,
    height,
    BABYLON.PhysicsUpdraftMode.Center // or BABYLON.PhysicsUpdraftMode.Perpendicular
);
// the second `radius` argument can also act as options: `.updraft(origin, { radius: radius, strength: strength, height: height, updraftMode: PhysicsUpdraftMode.Center })`
updraftEvent.enable();
setTimeout(() => updraftEvent.disable(), 5000);


// or


var vortexEvent = physicsHelper.vortex(
    origin,
    radius,
    strength,
    height
);
// the second `radius` argument can also act as options: `.vortex(origin, { radius: radius, strength: strength, height: height, centripetalForceThreshold: 0.7, centripetalForceMultiplier: 5, centrifugalForceMultiplier: 0.5, updraftForceMultiplier: 0.02 })`
vortexEvent.enable();
setTimeout(() => vortexEvent.disable(), 5000);

For a more detailed explanation, please take a look at the playground example below.

Physics helpers

Further reading

Using A Physics Engine
Learn how to use one of the available physics engines in Babylon.js.
Using A Physics Engine