Physics engines are third party external programs that can be plugged into Babylon.js. They, depending on their features, emulate "real-life" interactions between objects, which can be meshes, solid particles from the solid particle system or some caameras. One feature of a Physics Engine is the addition of gravity to a scene.
There are plugins for 3 physics engines:
All need to be enabled before use.
Interactions between objects are achieved by imposters, simple objects that are attached to any complex objects with a scene. To allow interaction between objects, the physics engines use an impostor, which is a simpler representation of a complex object. The imposter can be assigned physical attributes such as mass, friction and a coefficient of restitution.
It is also possible to assign linear and angular velocities to an imposter as well as an impulse and in the case of the Cannon and Ammo Physics Engines a force.
Two imposters can be connected using joints such as a hinge or ball and socket.
Collisions between two imposters P0 and P1 is handled by setting a callback function on P0 that determines the action when in contact with P1.
Ammo also allows the creation of soft bodies.