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I intend to make a game that takes place in space where one can land a craft on a larger "carrier" type ship, walk around on it, or even drive a little car about the decks. I would like to make a more complete artificial gravity system than just turning on "use gravity" for objects within the ship.

The method I am trying to use is to apply a downwards force on any object within a trigger collider. This way, if the carrier does a roll, none of the cargo will fall off into space.

function OnTriggerStay (other : Collider) {    

    if (other.attachedRigidbody) {
        other.attachedRigidbody.AddForce(0,other.attachedRigidbody.mass*-9.81,0);
    }
}

the problem is that whether I use "AddForce" or "AddRelativeForce" things on the ship dont seem to behave realistically.

Answer 1

If the ship is permanently fixed upright then gravitytype can be used, otherwise use forcetype where landing on a ship which is upside down you wont end up falling to the ceiling

var forcetype:boolean;
var gravitytype:boolean;

function OnTriggerStay(other : Collider) {

 if(forcetype){
       if (other.attachedRigidbody) {



         // Calculate the y-axis relative to us   
         var cameraRelativeRight : Vector3 = transform.TransformDirection (Vector3.up);
         // Apply a force relative to the our y-axis

       other.attachedRigidbody.AddForce(cameraRelativeRight * -9.81,ForceMode.Acceleration);
       }
    }


} 



//works if upright

function OnTriggerEnter(other : Collider) {
    if(gravitytype){

       if(other.attachedRigidbody) {
          other.attachedRigidbody.useGravity = true;

       }
    }
}

function OnTriggerExit(other : Collider){
    if(gravitytype){
       if (other.attachedRigidbody) {
         other.attachedRigidbody.useGravity = false;
       }
    }
}

Answer 2

0

Use

var gravityVector = Vector3(0, -9.81, 0);
rigidbody.AddForce( gravityVector * Time.deltaTime, ForceMode.Acceleration);

The main diffrences are that this does not take into account the mass of the object - just like gravity doesn't - and the ForceMode.Acceleration will make it behave more like gravity because gravity is an acceleration, not a constant force.

Also putting gravity in it's own vector makes it easier to modify

gravityVector = Vector3.up * 9.81; // :)

answered Jul 07 '11 at 10:57 PM

SilverTabby
1.9k ● 3 ● 6 ● 18

you want to use mothership.transform.up, not Vector3.up

Jan 18 '12 at 02:01 PM royce3

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