/PhysicsEngines/Farseer/FarseerJoint.cs

using Delta.Utilities.Datatypes;

using Delta.Utilities.Helpers;

using FarseerPhysics.Dynamics.Joints;

using FarseerPhysics.Factories;

using Microsoft.Xna.Framework;

using JointType = Delta.PhysicsEngines.Enums.JointType;



namespace Delta.PhysicsEngines.Farseer

{

	/// <summary>

	/// Farseer joint implementation.

	/// </summary>

	internal class FarseerJoint : PhysicsJoint

	{

		#region Joint (Public)

		/// <summary>

		/// Gets farseer joint object.

		/// </summary>

		public Joint Joint

		{

			get;

			private set;

		}

		#endregion



		#region Private



		#region physicsManager (Private)

		private readonly FarseerPhysics physicsManager;

		#endregion



		#endregion



		#region Constructors

		/// <summary>

		/// Creates a new instance of the <see cref="FarseerJoint"/> class.

		/// </summary>

		/// <param name="physicsManager">The physics manager.</param>

		/// <param name="jointType">Type of the joint.</param>

		/// <param name="bodyA">The body A.</param>

		/// <param name="bodyB">The body B.</param>

		/// <param name="args">The args.</param>

		public FarseerJoint(

			FarseerPhysics physicsManager,

			JointType jointType,

			PhysicsBody bodyA,

			PhysicsBody bodyB, object[] args)

			: base(jointType, bodyA, bodyB, args)

		{

			this.physicsManager = physicsManager;



			CreateJoint();

		}

		#endregion



		#region Methods (Private)



		#region CreateJoint

		/// <summary>

		/// Create joint from properties.

		/// </summary>

		private void CreateJoint()

		{

			var farseerBodyA = (BodyA as FarseerBody).Body;

			var farseerBodyB = (BodyB as FarseerBody).Body;



			Vector tempVector;

			switch (JointType)

			{

				case JointType.Angle:

					AngleJoint angleJoint = JointFactory.CreateAngleJoint(

						physicsManager.farseerPhysicsWorld,

						farseerBodyA,

						farseerBodyB);



					angleJoint.MaxImpulse = 3;

					angleJoint.TargetAngle =

						ArrayHelper.SafeGet<PropertyType, float>(

							base.Properties, PropertyType.TargetAngle);



					Joint = angleJoint;

					break;

				case JointType.Prismatic:

					PrismaticJoint prismaticJoint = JointFactory.CreatePrismaticJoint(

						farseerBodyA, farseerBodyB, Vector2.Zero, Vector2.Zero);

					Joint = prismaticJoint;

					break;



				case JointType.PointPointDistance:

					tempVector = ArrayHelper.SafeGet<PropertyType, Vector>(

						Properties, PropertyType.Anchor1);

					Vector2 anchor1 = FarseerDatatypesMapping.Convert(ref tempVector);



					tempVector = ArrayHelper.SafeGet<PropertyType, Vector>(

						Properties, PropertyType.Anchor2);

					Vector2 anchor2 = FarseerDatatypesMapping.Convert(ref tempVector);



					var distanceJoint = JointFactory.CreateDistanceJoint(

						physicsManager.farseerPhysicsWorld, farseerBodyA,

						farseerBodyB, anchor1, anchor2);



					// Calculate length

					var d = distanceJoint.BodyB.GetWorldPoint(distanceJoint.LocalAnchorB) -

					        distanceJoint.BodyA.GetWorldPoint(distanceJoint.LocalAnchorA);

					distanceJoint.Length = d.Length();

					break;

			}



			if (Joint != null)

			{

				Joint.CollideConnected = true;

			}

		}

		#endregion



		#endregion

	}

}