Physics Wheel

I think I've figured a way to get a physically accurate car behavior.

What would be required is a top-down wheel object that outputs:

• force in each axis (x,y) to be applied to the car
• torque to be applied to the car
• amount of skidding, measured in force lost (this becomes displaced material, sound and heat)
• Angular speed of the wheel (for animation and sound).

It would require as an input:

• A car body to which it is attached, as a sprite with physics and all drag set to 0.
• The position relative to the car body where it's attached.
• static and dynamic friction coefficient (change in runtime when terrain changes, set to 0 when on air)
• Car body's weight (or mass and gravity)
• Torque being applied to the wheel

And the equations are pretty standard physics. How does it sound?

A real car physical car model models each wheel individually and stuff... it's kinda complicated...

yeah that's why I'm talking about a single wheel object, not a car object.

This wheel would produce the info needed to apply the proper force to the car body, which in turn would drag the wheels.

It's complex but not hard pretty well documented and I studied it at some point.

I just gotta start working on the SDK.

One thing that could be annoying is weight. The wheel needs to know how much weight its supporting, but if I get this info automagically from a physics car body (based on body weight and relative position and assuming all wheels are at the same height) then you don't get to create multi-part articulated wheeled vehicles (8-wheelers, bycicles, etc) or to model suspension.

But suspension and weight distribution aren't trivial to calculate, doing so in events would make a physics wheel behavior really difficult to use.

Perhaps the behavior could have utility expressions to calculate those things. Hmm.

Sounds promising