It sounds like you want an entity with no physics shape associated with it (or possibly one where you can switch the physics shape on and off). The CameraEntity provides an example of one way to do this. Look at the IsPhysicsVisible property of the CameraEntity in samples\simulation\entities\entities.cs. When this property is set to true, the PhysicsEntity associated with the camera is added into the physics scene. When it is set to false, the PhysicsEntity is removed from the scene.
Probably the easiest way for you to do this is to define a new Entity that inherits from SingleShapeEntity. Add an IsPhysicsVisible property much like the CameraEntity property and then you will be able to easily switch the physics entity on and off.
-Kyle
OK. So you want a trigger shape that you can move around. Trigger shapes will not collide with other shapes, they allow other shapes to pass through them. It is better to make it a kinematic entity than a normal entity which contains static shapes. Kinematic entities are moved by you and not by the physics engine. The physics engine assumes that static shapes don't move at all.
To set an entity to be kinematic, you need to do the following after the entity has been initialized:
YourEntity.PhysicsEntity.IsKinematic = true;
One way to do this is to create a new entity type that inherits from the entity you are using. Override the Initialize method and set IsKinematic true:
public class KinematicSingleShapeEntity : SingleShapeEntity
{
public KinematicSingleShapeEntity() { }
public KinematicSingleShapeEntity(Shape shape, Vector3 initialPos)
: base(shape, initialPos)
{
}
public override void Initialize(xnagrfx.GraphicsDevice device, PhysicsEngine physicsEngine)
{
base.Initialize(device, physicsEngine);
PhysicsEntity.IsKinematic = true;
}
}
-Kyle
I noticed in another post that you were having a hard time creating a kinematic entity because your shapes had 0 mass. Why is this a requirement? Simply give your shapes a minimal mass to make them dynamic and you shouldn't have a problem making the entity kinematic.
-Kyle
Hi Kyle!
First of all thanks for considering this problem.
Due to the lack of proper documentation, I did lots of combination tests on my entity. My observations are given below. I hope that will help you understand the situation in a better way.
| Sr. No. | Trigger shape(s) mass | Non-trigger shape(s) present | Non-trigger shape(s) mass | IsKinematic | Remarks |
| 1. | 0 | No | N/A | Unable to set true | No error. State.Pose cannot be changed. PhysicsEntity.MovePose cannot be used. The entity is completely static. |
| 2. | >0 | No | N/A | N/A | ApplicationException in CreateAndInsertEntity. Message: "Physics engine failed to create entity" |
| 3. | 0 | Yes | 0 | Unable to set true | No error. State.Pose cannot be changed. PhysicsEntity.MovePose cannot be used. The entity is completely static. |
| 4. | 0 | Yes | >0 | Can be set to true or false | The non-trigger shape interacts with environment properly depending on IsKinematic. However, the non-trigger shape is not pass-through. Hence, the entity as a whole cannot be pass-through. |
| 5. | >0 | Yes | 0 | N/A | Same as Situation 2. ApplicationException in CreateAndInsertEntity. Message: "Physics engine failed to create entity" |
| 6. | >0 | Yes | >0 | Can be set to true or false | Same as Situation 4. The non-trigger shape interacts with environment properly depending on IsKinematic. However, the non-trigger shape is not pass-through. Hence, the entity as a whole cannot be pass-through. |
None of these conditions allow me to create an entity which satisfies all of these properties simultaneously:
I really don't understand what problem you are still facing. You just need to make an entity which contains one or more trigger shapes that have mass. Set the entity to be kinematic and you are done. Since it is kinematic, you can move it around however you want and its mass is irrelevant. Since it consists entirely of trigger shapes, it will not collide with other shapes. Isn't this exactly what you need?
-Kyle
You're right that the Ageia engine doesn't seem to like kinematic trigger shapes. I have not been able to find a way to create a kinematic trigger entity that is completely made up of trigger shapes. Your best bet is probably to go with situation 4 or 6 in the table above.
-Kyle
