How to calculate/detect the force of a collision? (Game-Maker Studio)

Question

How can I use game-maker to detect the force in a collision between two mobile (not fixed) objects?

This is used for damage calculation and possibly compression calculation.

My problem is this: while net force can be calculated using mass and acceleration, the idea of damage is focused on the individual components of the force applied on an object. For instance, if a car is pushing another car against a wall, even though there are no acceleration, people will logically feel like some damage must be done to both cars because forces were conferred on them. I want to know if there is some underlying mechanism in game maker's physics system (I use the latest version) that actually calculate a reaction force from the wall on the car so I can use it to calculate damage.

Answer 1

I found a solution to the particular problem that I am having:

I continue to use the physics system but instead of trying to dredge out the reaction forces acting on the object, I chose to create a "collision box" which I "attach" to all objects.

The box consists of multiple rectangles that surround a central geometry. The following code was used to give this rectangles, which I call "collision bars", a "springy" behavior:

if x!=X //X is the displacement of the collision bar from the central geometry
{
physics_apply_force(x,y,(x-X)^3,0)
}
//and the same is done for y

This means the collision bars are mobile around the central geometry but restores to a specific relative location.

If another object collide with the collision bar, there will be a displacement in the location of the collision bar, and the greater the "force of collision" the greater the force, and I can consequently use the collision bar's displacement from the central geometry to calculate the force applied on the object from a specific direction.

This may not be the most efficient or the most elegant method, but it works for the game that I am working on well enough.