koobas.hobune.stream
Rigidbody2D and ForceMode.AddVelocity?
The new 2D update (Unity v4.3, released 2013-11-12) have come with the new Rigidbody2D component.
My previous code uses the 3D-based rigidbody, moving it using Rigidbody.AddForce(). I specified that the AddForce() uses ForceMode.VelocityChange, which conveniently ignores mass and just makes it better for a playable character.
Rigidbody2D.AddForce() on the other hand does not support ForceMode at all, it has only one way of dealing with velocity and that is 'force = mass * acceleration'.
Here's the part of my code that applies the target velocity to the rigidbody:
/* Apply motion */
Vector3 _velocity = myRigidbody.velocity;
Vector3 _velocityChange = (TargetVelocity - _velocity);
/* Move rigidbody */
myRigidbody.AddForce(_velocityChange,ForceMode.VelocityChange);
How to convert this movement to the Rigidbody2D? Preferably I am looking for an identical conversion, as I am quite keen on how the character feels right now when moving.
Yeah, no forcemodes (yet?) on Rigidbody2D. However, you should be able to the same result as ForceMode.VelocityChange by just adding your new velocity to the rigidbody2D.velocity.
Here are some extension methods for Physics2D to add this missing functionality to AddForce, strongly based on the solution by gfoot at this thread.
public static class Physics2DExtensions {
public static void AddForce (this Rigidbody2D rigidbody2D, Vector2 force, ForceMode mode = ForceMode.Force) {
switch (mode) {
case ForceMode.Force:
rigidbody2D.AddForce (force);
break;
case ForceMode.Impulse:
rigidbody2D.AddForce (force / Time.fixedDeltaTime);
break;
case ForceMode.Acceleration:
rigidbody2D.AddForce (force * rigidbody2D.mass);
break;
case ForceMode.VelocityChange:
rigidbody2D.AddForce (force * rigidbody2D.mass / Time.fixedDeltaTime);
break;
}
}
public static void AddForce (this Rigidbody2D rigidbody2D, float x, float y, ForceMode mode = ForceMode.Force) {
rigidbody2D.AddForce (new Vector2 (x, y), mode);
}
}
Force mode has been added 2d rigidbodies
As of version 5.61f1, still only half-implemented, and missing the mass-ignoring modes (Acceleration and VelocityChange)... Sincerely, can't see why unity doesn't use the good old Force$$anonymous$$ode type for both 3D and 2D.
