/* Sparx
 * Copyright August Zinsser 2007
 * This program is distributed under the terms of the GNU General Public License
 */


using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;


namespace Pina3D.Particles
{
    public class Vortex : Force
    {
        private Emitter mCenter;
        private Vector3 mCentralDisplacement;
        private bool mClockwise;

        public Emitter Center { set { mCenter = value; } get { return mCenter; } }
        /// <summary>
        /// Displaces the center of rotation from the central object by this amount
        /// </summary>
        public Vector3 CentralDisplacement { set { mCentralDisplacement = value; } get { return mCentralDisplacement; } }
        public bool Clockwise { set { mClockwise = value; } get { return mClockwise; } }


        public Vortex(string name, float lifeSpan, float delay, Emitter center, Vector3 centralDisplacement, float magnitude, bool clockwise)
            : base(name, lifeSpan, delay)
        {
            mCenter = center;
            mMagnitude = magnitude;
            mCentralDisplacement = centralDisplacement;
            mClockwise = clockwise;
        }


        public override Object Clone()
        {
            Vortex retFo = new Vortex(mName + "_clone", mAge, mDelay, mCenter, mCentralDisplacement, mMagnitude, mClockwise);
            return retFo;
        }


        public override void Update(Emission emission)
        {
            if (mCenter != null && emission.Age > mDelay && emission.Age < mLifeExpectancy + mDelay)
            {
                RecalculateForceVector(emission);
                emission.Velocity3D += Vector3.Multiply(mForceVector, Pina.ElapsedSeconds);
            }
        }


        /// <summary>
        /// Makes a force vector that is perpindicular to the center-thispoint vector, and adds that to regular angular acceleration
        /// </summary>
        /// <param name="emission"></param>
        private void RecalculateForceVector(Emission newCenter)
        {
            // TODO: this function in 3D

            //Vector3 toCenter = mCenter.Position3D + mCentralDisplacement - newCenter.Position3D;
            //float r2 = (float)toCenter.LengthSquared();

            //// For clockwise rotation, cross this vector with a +z vector
            //Vector3 zVec = mClockwise ? new Vector3(0, 0, -mMagnitude) : new Vector3(0, 0, mMagnitude);
            //Vector3 fVec = new Vector3(toCenter.X, toCenter.Y, 0);
            //Vector3 rVec = Vector3.Cross(zVec, fVec);

            //mForceVector = new Vector3(rVec.X, rVec.Y);

            //// Add a centripetal force
            //toCenter.Normalize();
            //mForceVector += Vector2.Multiply(toCenter, r2);
        }
    }
}