ParticleGravity.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 pulls all particles by a common gravity.
    /// </summary>
    /// <example>
    /// The following example puts a vertical gravity of 0.4f in the particleSystem.
    /// <code>
    /// ParticleGravity grav = new ParticleGravity(0.4f);
    /// particleSystem.Add(grav);
    /// </code>
    /// </example>
    public class ParticleGravity : IParticleManipulator
    {
        private Vector m_Velocity = new Vector(0f, 0.2f, 0);
        /// <summary>
        /// Creates a new ParticleSystem with a common gravity.
        /// </summary>
        /// <param name="velocity">The velocity (horizontal and vertical) of the particle system.</param>
        public ParticleGravity(Vector velocity)
        {
            m_Velocity = velocity;
        }

        /// <summary>
        /// Creates a new ParticleSystem using gravity and wind.
        /// </summary>
        /// <param name="gravity">The vertical gravity of the system.</param>
        /// <param name="wind">The horizontal gravity of the system.  This is commonly refered to as wind.</param>
        public ParticleGravity(float gravity, float wind)
            : this(new Vector(wind, gravity, 0))
        {
        }

        /// <summary>
        /// Creates a new ParticleSystem with a vertical gravity.
        /// </summary>
        /// <param name="gravity">The vertical gravity of the system.</param>
        public ParticleGravity(float gravity)
            : this(new Vector(0, gravity, 0))
        {
        }

        /// <summary>
        /// Creates a new ParticleSystem.
        /// </summary>
        /// <remarks>The gravity defaults as "new Vector()".</remarks>
        public ParticleGravity()
            : this(new Vector())
        {
        }

        /// <summary>
        /// Gets and sets the velocity (direction and speed) of the gravity as a vector.
        /// </summary>
        public Vector Velocity
        {
            get
            {
                return m_Velocity;
            }
            set
            {
                m_Velocity = value;
            }
        }

        /// <summary>
        /// Gets and sets the vertical pull of the gravity.
        /// </summary>
        public float Gravity
        {
            get
            {
                return m_Velocity.Y;
            }
            set
            {
                m_Velocity.Y = value;
            }
        }

        /// <summary>
        /// Gets and sets the horizontal push of the gravity.
        /// </summary>
        public float Wind
        {
            get
            {
                return m_Velocity.X;
            }
            set
            {
                m_Velocity.X = value;
            }
        }

        #region IParticleManipulator Members

        /// <summary>
        /// Manipulate particles by the gravity.
        /// </summary>
        /// <param name="particles">The particles to pull by the gravity.</param>
        public void Manipulate(ParticleCollection particles)
        {
            if (particles == null)
            {
                throw new ArgumentNullException("particles");
            }
            foreach (BaseParticle p in particles)
            {
                p.Velocity += m_Velocity;
            }
        }

        #endregion
    }
}