Physics Aggregate vs Physics Body

Questions
1

Hello, I was wondering if someone could help me with basic physics. I read through the physics documentation and it seems to all makes sense, however in practice I can’t seem to use the static PhysicsMotionType.

The physics documentation describes both physics bodies (as well as outlining the importance of using static flags). I don’t understand the difference between them and why the boxes go through the floor when I use PhysicsBody. (Using PhysicsBody for either the wall/floor or boxes makes the boxes go through the floor, I need to use aggregates for both the floor/wall and the boxes for it to work).

I’m a bit confused about how to make the the boxes respond to the floor, or mark the aggregate as static (maybe my understanding of the whole thing is flawed).

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Here are the boxes correctly dropped down into the world (again, I need to use aggregates for everything for this to work).

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Thank you for taking the time to read.

2

Hi @brandon-xyz and welcome to the forum!

There are 3 types of motion

  • static: nothing moves
  • kinematic: animation is controlled outside of physics (like automatic door controlled by an animation Curve in Blender)
  • dynamic: it moves and controlled by physics engine

More explanation here : Physics V2 core concepts | Babylon.js Documentation

As a shortcut and to be consistent with physics V1, settting mass = 0 makes the physics body to be static

1 Like
3

Thank you!

So yes, that link you mentioned refers to using PhysicsBodies, and that’s what I’m wondering about.

For example if I add this to the scene as outlined in that link.


		const sphere = BABYLON.MeshBuilder.CreateSphere("sphere");
		sphere.position.y = 100;
		const body = new BABYLON.PhysicsBody(sphere, BABYLON.PhysicsMotionType.DYNAMIC, false, scene);


		body.setMassProperties({
			mass: 1,
		});

It will simply fall through the floor, when the other objects stop on top of it.

4

Can you share the scene in a Playground so we can take a better look?