source: 2014/24/EemeliK/Zombieland/Jypeli/GameObjects/PhysicsObject/Inertia.cs @ 5974

#region MIT License
/*
 * Copyright (c) 2009 University of Jyväskylä, Department of Mathematical
 * Information Technology.
 * 
 * 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

/*
 * Authors: Tero Jäntti, Tomi Karppinen, Janne Nikkanen.
 */

using System;
using Physics2DDotNet;
using Physics2DDotNet.Shapes;

namespace Jypeli
{
    public partial class PhysicsObject
    {
        private const double DefaultMass = 1.0;
        private bool _momentOfInertiaSet = false;

        /// <summary>
        /// Jos <c>false</c>, olio ei voi pyöriä.
        /// </summary>
        public bool CanRotate
        {
            get { return !double.IsPositiveInfinity( MomentOfInertia ); }
            set
            {
                if ( !value )
                {
                    MomentOfInertia = double.PositiveInfinity;
                    _momentOfInertiaSet = true;
                }
                else
                {
                    SetMassAndInertia( this.Mass );
                    _momentOfInertiaSet = false;
                }
            }
        }

        /// <summary>
        /// Olion massa. Mitä suurempi massa, sitä suurempi voima tarvitaan olion liikuttamiseksi.
        /// </summary>
        /// <remarks>
        /// Massan asettaminen muuttaa myös hitausmomenttia (<c>MomentOfInertia</c>).
        /// </remarks>
        public double Mass
        {
            get { return Body.Mass.Mass; }
            set
            {
                // We change the moment of inertia as well. If the mass is changed from
                // 1.0 to 100000.0 for example, it would look funny if a heavy object would
                // spin wildly from a small touch.

                if ( _momentOfInertiaSet )
                {
                    // The moment of inertia has been set manually,
                    // let's keep it that way and just set the mass.
                    Body.Mass.Mass = value;
                }
                else
                {
                    SetMassAndInertia( value );
                }
            }
        }

        /// <summary>
        /// Olion hitausmomentti. Mitä suurempi hitausmomentti, sitä enemmän vääntöä tarvitaan
        /// olion pyörittämiseksi.
        /// </summary>
        public double MomentOfInertia
        {
            get { return Body.Mass.MomentOfInertia; }
            set
            {
                Body.Mass.MomentOfInertia = value;
                _momentOfInertiaSet = true;
            }
        }

        /// <summary>
        /// Tekee suorakulmaisen kappaleen, joka on staattinen (eli pysyy paikallaan).
        /// </summary>
        /// <param name="width">Kappaleen leveys</param>
        /// <param name="height">Kappaleen korkeus</param>
        /// <returns>Fysiikkaolio</returns>
        public static PhysicsObject CreateStaticObject( double width, double height )
        {
            PhysicsObject o = new PhysicsObject( width, height );
            o.MakeStatic();
            return o;
        }

        /// <summary>
        /// Tekee suorakulmaisen kappaleen, joka on staattinen (eli pysyy paikallaan).
        /// Kappaleen koko ja ulkonäkö ladataan parametrina annetusta kuvasta.
        /// </summary>
        /// <param name="width">Kappaleen leveys</param>
        /// <param name="height">Kappaleen korkeus</param>
        /// <returns>Fysiikkaolio</returns>
        public static PhysicsObject CreateStaticObject( Image image )
        {
            PhysicsObject o = new PhysicsObject( image );
            o.MakeStatic();
            return o;
        }

        /// <summary>
        /// Tekee vapaamuotoisen kappaleen, joka on staattinen (eli pysyy paikallaan).
        /// </summary>
        /// <param name="width">Kappaleen leveys</param>
        /// <param name="height">Kappaleen korkeus</param>
        /// <param name="shape">Kappaleen muoto</param>
        /// <returns>Fysiikkaolio</returns>
        public static PhysicsObject CreateStaticObject( double width, double height, Shape shape )
        {
            PhysicsObject o = new PhysicsObject( width, height, shape );
            o.MakeStatic();
            return o;
        }

        [Obsolete( "Use CollisionShapeParameters or the PhysicsTemplates class." )]
        internal static PhysicsObject CreateStaticObject( double width, double height, Shape shape, CollisionShapeQuality quality )
        {
            PhysicsObject o = new PhysicsObject( width, height, shape );
            o.MakeStatic();
            return o;
        }

        public static PhysicsObject CreateStaticObject( double width, double height, Shape shape, CollisionShapeParameters parameters )
        {
            PhysicsObject o = new PhysicsObject( width, height, shape, parameters );
            o.MakeStatic();
            return o;
        }

        [Obsolete( "Use function with CollisionShapeParameters" )]
        internal static PhysicsObject CreateStaticObject( double width, double height, Shape shape, double maxDistanceBetweenVertices, double gridSpacing )
        {
            PhysicsObject o = new PhysicsObject( width, height, shape, maxDistanceBetweenVertices, gridSpacing );
            o.MakeStatic();
            return o;
        }

        internal static PhysicsObject CreateStaticObject( double width, double height, Shape shape, IShape physicsShape )
        {
            PhysicsObject o = new PhysicsObject( width, height, shape, physicsShape );
            o.MakeStatic();
            return o;
        }

        /// <summary>
        /// Tekee oliosta staattisen. Staattinen olio ei liiku muiden olioiden törmäyksistä,
        /// vaan ainoastaan muuttamalla suoraan sen paikkaa tai nopeutta.
        /// </summary>
        public void MakeStatic()
        {
            Mass = double.PositiveInfinity;
            CanRotate = false;
            IgnoresGravity = true;
        }

        /// <summary>
        /// Olion hidastuminen. Hidastaa olion vauhtia, vaikka se ei
        /// osuisi mihinkään. Vähän kuin väliaineen (esim. ilman tai veden)
        /// vastus. Oletusarvo on 1.0, jolloin hidastumista ei ole. Mitä
        /// pienempi arvo, sitä enemmän kappale hidastuu.
        /// 
        /// Yleensä kannattaa käyttää arvoja, jotka ovat lähellä ykköstä,
        /// esim. 0.95.
        /// </summary>
        public double LinearDamping
        {
            get { return Body.LinearDamping; }
            set { Body.LinearDamping = value; }
        }

        /// <summary>
        /// Olion pyörimisen hidastuminen.
        /// 
        /// <see cref="LinearDamping"/>
        /// </summary>
        public double AngularDamping
        {
            get { return Body.AngularDamping; }
            set { Body.AngularDamping = value; }
        }

        /// <summary>
        /// This updates the mass and momentOfInertia based on the new mass.
        /// </summary>
        private void SetMassAndInertia( double mass )
        {
            Body.Mass = Body.GetMassInfo( mass, Body.Shape );
        }
    }
}