if body is colliding

[Overhertz]

hi, i'm looking for a solution to add a force to a body IF the body is currently touching something. i can't find a solution to this. anyone can help?

[Julio Jerez]

that is what the phyiscs engine does.

there is no way to do that with ouy beraking the solver,
you can try chnegoin teh normal acceleration is a contact callack, bu I do not thnk I ever done that.

[JernejL]

you can use the contacts iterator in the forcetorque callback to check if body has touched something in previous frame.

[Overhertz]

basically i want to do something like >

Code: Select all

procedure VehicleForceAndTorqueCallback(const body: PNewtonBody; timestep: float; threadindex: integer); cdecl;
var
  obj: TZLVehicle;
  Mass    : Single;
  Inertia : Vector3df;
  Force   : Vector3df;
  bodymat: Matrix4;

  newvl: Vector3df;
  outbl: Vector3df;
begin
  obj := NewtonBodyGetUserData(body);

  NewtonBodyGetMassMatrix(body, @Mass, @Inertia.x, @Inertia.y, @Inertia.z);
  NewtonBodyGetMatrix(body, bodymat.pointer);


  //if body of wheel x and y is touching something then >
  if obj.Reverse = True then begin
    newvl.x := -obj.fRevols*4; newvl.y := 0; newvl.z := 0;
  end else begin
    newvl.x := obj.fRevols*8; newvl.y := 0; newvl.z := 0;
  end;
  bodymat.rotateVect(outbl, newvl);
  //

  Force := getvector3df(outbl.x, (NEWTON_GRAVITY * Mass) + outbl.y, outbl.z);
  NewtonBodyAddForce(body, @Force.X);
end;


i want to simulate force transferal from gripping wheels to the body, when the front wheels spin (without this force, they overspin and max speed at 50) i currently implemented this and it can give a realistic result for speed and performance without tweaking newton, my only problem is i need this force only transferred when the wheels are on the ground (in the air is a bit silly to grip something.... lol) however it works really well now, if i can get this solved then i will release a demo of it working.