Trigger Contact Material Pair?

[samisaham]

I am having trouble figuring out how to get the materialPair userdata in the NewtonContactsProcess callback when one of the objects is a trigger volume. Is there a way to do this yet? I am using Newton 2 beta. I tried the following without success:

Code: Select all

void HandleContactLevel (const NewtonJoint* contactJoint, dFloat timestep, int threadIndex)
{
   NewtonMaterial* material;
   BUOYANCYDAT* info;

   void* contact = NewtonContactJointGetFirstContact (contactJoint);
   material = NewtonContactGetMaterial (contact);
   info = (BUOYANCYDAT*)NewtonMaterialGetMaterialPairUserData(material);
}

I have been experimenting and searching the forums and tutorials but to no avail. Any help would be much appreciated!
Thanks,
-hanson

[samisaham]

This is rather important to me. Is there any way to get the material pair userData for collisions with a trigger volume?

[JernejL]

In newton2 you receive a contactjoint, you need to iterate the contactjoint for all contacts, and use things like NewtonJointGetBody0, NewtonJointGetBody1, NewtonBodyGetMaterialGroupID, NewtonMaterialGetUserData there.

Example code how to use new material callback in newton2 for delphi:

Code: Select all


function CarHitCar(const contact: PNewtonJoint; timestep: float; threadindex: integer): longint; cdecl;
var
  pos, nor:    vector;
  ImpactForce: single;
  TotalDamage: single;
  ContactCar0, ContactCar1: Tcar;
  material:    Pnewtonmaterial;
  ThisContact: PNewtonJoint;
begin

  ContactCar0 := NewtonBodyGetUserData(NewtonJointGetBody0(contact));
  ContactCar1 := NewtonBodyGetUserData(NewtonJointGetBody1(contact));

  // use NewtonBodyGetMaterialGroupID and NewtonMaterialGetUserData for both bodies here..

  Result      := 1;
  TotalDamage := 0;

  ThisContact := NewtonContactJointGetFirstContact(contact);

  while ThisContact <> nil do
  begin
    material := NewtonContactGetMaterial(ThisContact);

    NewtonMaterialGetContactPositionAndNormal(material, @pos, @nor);

    ThisContact := NewtonContactJointGetNextContact(contact, ThisContact);
  end;





[samisaham]

Thanks so much! I finally got it working:

Code: Select all

const NewtonBody* body0;
const NewtonBody* body1;
BUOYANCYDAT* info;

body0 = NewtonJointGetBody0 (contactJoint);
body1 = NewtonJointGetBody1 (contactJoint);
info = (BUOYANCYDAT*)NewtonMaterialGetUserData(NewtonBodyGetWorld(body0), NewtonBodyGetMaterialGroupID(body0),NewtonBodyGetMaterialGroupID(body1));


I'd think there would be an easier way as there was with the old method, but in any case I'm glad it's working now

Thanks
-Sam Hanson

[Carli]

a c++man able to read pascal code???? very rare

[JernejL]

a c++man able to read pascal code???? very rare

When you look at details.. the pascal / delphi syntax is not as different from c++ as it appears

[Carli]

i know - that's the reason why i can't understand c++mans who are not able to read pascal (espeacially opengl-commands )

i love pascal - espeacially the platform-independency of lazarus/freepascal