#region MIT License
/*
* Copyright (c) 2005-2008 Jonathan Mark Porter. http://physics2d.googlepages.com/
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#endregion
#if UseDouble
using Scalar = System.Double;
#else
using Scalar = System.Single;
#endif
using System;
using AdvanceMath;
namespace Physics2DDotNet.PhysicsLogics
{
/// <summary>
/// A Gravity Field that apply gravity pulling in one direction regardless of the Body's position with zero dropoff.
/// </summary>
[Serializable]
public sealed class GravityField : PhysicsLogic
{
Vector2D gravity;
/// <summary>
/// Creates a new GravityField Instance.
/// </summary>
/// <param name="gravity">The direction and magnitude of the gravity.</param>
/// <param name="lifeTime">A object Describing how long the object will be in the engine.</param>
public GravityField(Vector2D gravity, Lifespan lifetime)
: base(lifetime)
{
this.gravity = gravity;
}
protected internal override void RunLogic(TimeStep step)
{
foreach (Body e in this.Bodies)
{
if (e.IgnoresGravity ||
e.IgnoresPhysicsLogics)
{
continue;
}
Vector2D.Add(ref e.State.Acceleration.Linear, ref gravity, out e.State.Acceleration.Linear);
}
}
}
}