ParticleFriction.cs :  » Game » SDL » SdlDotNet » Particles » Manipulators » C# / CSharp Open Source

#region LICENSE
/*
 * Copyright (C) 2005 Rob Loach (http://www.robloach.net)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#endregion LICENSE

using System;

using SdlDotNet.Core;
using SdlDotNet.Particles;

namespace SdlDotNet.Particles.Manipulators{
    /// <summary>
    /// A particle manipulator that slows down particles by a given amount of speed.
    /// </summary>
    /// <example>
    /// The following example creates a particle friction manipulator that slows particles down by 0.5f every update.
    /// <code>
    /// ParticleFriction friction = new ParticleFriction(0.5f);
    /// particleSystem.Add(friction);
    /// </code>
    /// </example>
    public class ParticleFriction : IParticleManipulator
    {
        /// <summary>
        /// Create a ParticleFriction object with the default amount of friction.
        /// </summary>
        public ParticleFriction()
        {
        }
        /// <summary>
        /// Create a ParticleFriction object.
        /// </summary>
        /// <param name="friction">The amount of friction to apply to the particles.</param>
        public ParticleFriction(float friction)
        {
            m_Friction = friction;
        }

        private float m_Friction = 0.1f;
        /// <summary>
        /// Gets and sets the amount of friction applied to the particles.
        /// </summary>
        public float Friction
        {
            get
            {
                return m_Friction;
            }
            set
            {
                m_Friction = value;
            }
        }

        #region IParticleManipulator Members

        /// <summary>
        /// Applies the friction to the given set of particles.
        /// </summary>
        /// <param name="particles">The particles to apply the friction to.</param>
        public void Manipulate(ParticleCollection particles)
        {
            if (particles == null)
            {
                throw new ArgumentNullException("particles");
            }
            foreach (BaseParticle p in particles)
            {
                Vector vel = p.Velocity;
                vel.Length -= m_Friction;
                p.Velocity = vel;
                //p.Velocity.Length -= m_Friction;
            }
        }

        #endregion
    }
}