Working on a general physics engine

[_Nate_]

I'm working on a general physics engine for fun.

Objects have two velocity vectors: rotation and translation. When a collision is detected, objects are told the point of collision (p) and the object that they hit.

The object decomposes its translational velocity into the component pointing towards p and the orthogonal component. It removes the former component from its own translational velocity and applies the component to the object that it hit. (Scaled, of course, by elasticity, etc)

This goes on to calculate equal and opposite reactions, etc. to simulate physics.

However, I don't know what to do with the rotational velocity when object a hits object b. Say that object a is spinning with a rotational velocity of r, and it hits object b at point p (which is direction u from a's center of mass). How is r applied to b?

 

[Aaron Barnard]

My initial idea is to decompose r into the component pointing in direction u and the orthogonal component (similar to translational velocity). The u-component is applied to b and the orthogonal component is ignored. This works for some scenarios, however, it doesn't always accurately simulate physics.

Is there a better way to apply an object's rotational velocity when a collision occurs?

 

[astrokreng]

It's great to hear that you are working on a general physics engine for fun. Physics engines are important tools in various fields, from video game development to engineering simulations. Your approach to handling collisions seems to be on the right track, as it takes into account both translational and rotational velocities.

When object A collides with object B at point P, the rotational velocity of A should be transferred to B in a similar manner as the translational velocity. The first step would be to calculate the relative velocity between the two objects at the point of collision. This includes both the translational and rotational components. Then, using the principle of conservation of angular momentum, you can calculate the new rotational velocity of B after the collision.

The direction and magnitude of the new rotational velocity will depend on the specific properties of the objects, such as their masses and moments of inertia. It's important to also consider the elasticity of the collision, as this will affect the amount of energy transferred between the objects.

In summary, when object A collides with object B, its rotational velocity should be transferred to B using the principle of conservation of angular momentum. This will ensure that your physics engine accurately simulates the behavior of rotating objects in collisions. Keep up the good work and happy coding!