How to hide body during runtime.

[benjaminleezhiyuan]

Hi, currently in my game engine I have this function

void SetActive(bool value, uint64_t* outEntityID)
{
	auto entity = SceneManager::GetActiveScene()->GetEntityByUUID(*outEntityID);
	if (entity)
	{
		entity.GetComponent<TagComponent>().active = value;
	}
	if (value)
	{
		//Activate
		if (entity.HasComponent<BoxColliderComponent>()) {
			PhysicsSystem::SetActive(entity.GetComponent<BoxColliderComponent>().bodyID);
		}

		if (entity.HasComponent<CapsuleColliderComponent>()) {
			PhysicsSystem::SetActive(entity.GetComponent<CapsuleColliderComponent>().bodyID);
		}

		if (entity.HasComponent<SphereColliderComponent>()) {
			PhysicsSystem::SetActive(entity.GetComponent<SphereColliderComponent>().bodyID);
		}

		if (entity.HasComponent<CylinderColliderComponent>()) {
			PhysicsSystem::SetActive(entity.GetComponent<CylinderColliderComponent>().bodyID);
		}
	}

	else

	{
		// decativate
		if (entity.HasComponent<BoxColliderComponent>()) {
			PhysicsSystem::SetInactive(entity.GetComponent<BoxColliderComponent>().bodyID);
		}

		if (entity.HasComponent<CapsuleColliderComponent>()) {
			PhysicsSystem::SetInactive(entity.GetComponent<CapsuleColliderComponent>().bodyID);
		}

		if (entity.HasComponent<SphereColliderComponent>()) {
			PhysicsSystem::SetInactive(entity.GetComponent<SphereColliderComponent>().bodyID);
		}

		if (entity.HasComponent<CylinderColliderComponent>()) {
			PhysicsSystem::SetInactive(entity.GetComponent<CylinderColliderComponent>().bodyID);
		}
	}
} 

That determines if an entity is visible or not. However if it is set to false, the body created remains as an invisible collider.

This is the definition of the SetActive and SetInactive.

 void PhysicsSystem::SetActive(unsigned int bodyID)
	{
		if (!sPhysicsData.body_interface->IsAdded((BodyID)bodyID))
		{
			sPhysicsData.body_interface->AddBody((BodyID)bodyID,EActivation::Activate);
		}
	}

	void PhysicsSystem::SetInactive(unsigned int bodyID)
	{
		if (sPhysicsData.body_interface->IsAdded((BodyID)bodyID))
		{
			sPhysicsData.body_interface->RemoveBody((BodyID)bodyID);
		}
	}

The body of the entity still remains as I am able to see it in the debugrender and collide with it.
Does it have something to do with require locking of the body?

[jrouwe]

I would expect RemoveBody to completely remove it from the world. This should stop rendering it and you should certainly not collide with it. The locking body interface only needs to be used if you add/remove bodies/query from multiple threads.

Have you stepped into the code? It must early out somewhere (maybe the bodyID is invalid)?

[benjaminleezhiyuan]

Ok I'm not really sure what happened but now it seems to work as intended.
Also on a sidenote, could you tell me what the different colours of the debug renderer mean?
I remember it had something to do with the body properties. I saw documentation before but I can't seem to find it anymore.

[jrouwe]

This is what determines the color:

JoltPhysics/Jolt/Physics/Body/BodyManager.cpp

Lines 921 to 1013 in c93401e

	Color color;
	if (is_sensor)
	color = Color::sYellow;
	else
	switch (inDrawSettings.mDrawShapeColor)
	{
	case EShapeColor::InstanceColor:
	// Each instance has own color
	color = Color::sGetDistinctColor(body->mID.GetIndex());
	break;
	case EShapeColor::ShapeTypeColor:
	color = ShapeFunctions::sGet(body->GetShape()->GetSubType()).mColor;
	break;
	case EShapeColor::MotionTypeColor:
	// Determine color based on motion type
	switch (body->mMotionType)
	{
	case EMotionType::Static:
	color = Color::sGrey;
	break;
	case EMotionType::Kinematic:
	color = Color::sGreen;
	break;
	case EMotionType::Dynamic:
	color = Color::sGetDistinctColor(body->mID.GetIndex());
	break;
	default:
	JPH_ASSERT(false);
	color = Color::sBlack;
	break;
	}
	break;
	case EShapeColor::SleepColor:
	// Determine color based on motion type
	switch (body->mMotionType)
	{
	case EMotionType::Static:
	color = Color::sGrey;
	break;
	case EMotionType::Kinematic:
	color = body->IsActive()? Color::sGreen : Color::sRed;
	break;
	case EMotionType::Dynamic:
	color = body->IsActive()? Color::sYellow : Color::sRed;
	break;
	default:
	JPH_ASSERT(false);
	color = Color::sBlack;
	break;
	}
	break;
	case EShapeColor::IslandColor:
	// Determine color based on motion type
	switch (body->mMotionType)
	{
	case EMotionType::Static:
	color = Color::sGrey;
	break;
	case EMotionType::Kinematic:
	case EMotionType::Dynamic:
	{
	uint32 idx = body->GetMotionProperties()->GetIslandIndexInternal();
	color = idx != Body::cInactiveIndex? Color::sGetDistinctColor(idx) : Color::sLightGrey;
	}
	break;
	default:
	JPH_ASSERT(false);
	color = Color::sBlack;
	break;
	}
	break;
	case EShapeColor::MaterialColor:
	color = Color::sWhite;
	break;
	default:
	JPH_ASSERT(false);
	color = Color::sBlack;
	break;
	}