Distorted Android

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// Copyright 2016 Leszek Koltunski                                                               //

//                                                                                               //

// This file is part of Distorted.                                                               //

//                                                                                               //

// Distorted is free software: you can redistribute it and/or modify                             //

// it under the terms of the GNU General Public License as published by                          //

// the Free Software Foundation, either version 2 of the License, or                             //

// (at your option) any later version.                                                           //

//                                                                                               //

// Distorted 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 General Public License for more details.                                                  //

//                                                                                               //

// You should have received a copy of the GNU General Public License                             //

// along with Distorted.  If not, see <http://www.gnu.org/licenses/>.                            //

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package org.distorted.library.type;

import java.util.Vector;

///////////////////////////////////////////////////////////////////////////////////////////////////

/** 

* A 4-dimensional implementation of the Dynamic class to interpolate between a list

* of Static4Ds.

* Here, the Points are assumed to be Quaternions - thus we do the Spherical Linear Interpolation, aka

* SLERP. Noise not supported (yet?).

*

* Only unit quaternions represent valid rotations in 3D - and interpolating through rotations is the

* most common use case for this class. No effort is done to normalize the Points though.

*

* Rotation Quaternion is assumed to be in the form ( axisX*sinT, axisY*sinT, axisZ*sinT, cosT ).

*/

public class DynamicQuat extends Dynamic implements Data4D

  {

///////////////////////////////////////////////////////////////////////////////////////////////////

// Here we implement our own Cache as we need something slightly different.

// omega, sinOmega, cosOmega - angle between pair of quaternions, its sinus and cosinus.

//  

// (vx,vy,vz,vw) is the original vector from vv (copied here so when interpolating we can see if it is 

// still valid and if not - rebuild the Cache.

  private class VectorCacheQuat

    {

    float omega, sinOmega,cosOmega;

    float vx,vy,vz,vw;

    }

  private Vector<VectorCacheQuat> vc;

  private VectorCacheQuat tmp1, tmp2;

  private Vector<Static4D> vv;

  private Static4D curr, next;

///////////////////////////////////////////////////////////////////////////////////////////////////

// Abramowitz / Stegun

  private static float arcCos(float x)

    {

    if( x<0 )

      return 3.14159265358979f - (float)Math.sqrt(1+x)*(1.5707288f + 0.2121144f*x + 0.074261f*x*x + 0.0187293f*x*x*x);

    return (float)Math.sqrt(1-x)*(1.5707288f - 0.2121144f*x + 0.074261f*x*x - 0.0187293f*x*x*x);

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

  private void recomputeCache()

    {  

    if( numPoints>=2 )

      {

      int i, n;  

      Static4D cu,ne;

      VectorCacheQuat vq;

      for(i=0; i<numPoints; i++)

        {

        n = i<numPoints-1 ? i+1:0;  

        vq= vc.elementAt(i);

        cu= vv.elementAt(i);

        ne= vv.elementAt(n);

        vq.vx = cu.x;

        vq.vy = cu.y;

        vq.vz = cu.z;

        vq.vw = cu.w;

        vq.cosOmega = cu.x*ne.x + cu.y*ne.y + cu.z*ne.z + cu.w*ne.w;

        vq.sinOmega = (float)Math.sqrt(1-vq.cosOmega*vq.cosOmega);

        vq.omega    = arcCos(vq.cosOmega);

        }

      }

    cacheDirty = false;

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

// PUBLIC API

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Default constructor.

 */

  public DynamicQuat()

    {

    this(0,0.5f);

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Constructor setting the speed of interpolation and the number of revolutions.

 *

 * What constitutes 'one revolution' depends on the MODE:

 * {@link Dynamic#MODE_LOOP}, {@link Dynamic#MODE_PATH} or {@link Dynamic#MODE_JUMP}.

 *

 * @param duration number of milliseconds it takes to do one revolution.

 * @param count    number of revolutions we will do. Count<=0 means 'infinite'.

 */

  public DynamicQuat(int duration, float count)

    {

    vv         = new Vector<>();

    vc         = new Vector<>();

    numPoints  = 0;

    cacheDirty = false;

    mMode      = MODE_LOOP;

    mDuration  = duration;

    mCount     = count;

    mLastPos   = -1;

    mAccessType = ACCESS_TYPE_RANDOM;

    mDimension = 4;

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Returns the location'th Static4D.

 *   

 * @param location the index of the Point we are interested in.

 * @return The Static4D, if 0<=location&lt;getNumPoints(), or null otherwise.

 */  

  public synchronized Static4D getPoint(int location)

    {

    return (location>=0 && location<numPoints) ? vv.elementAt(location) : null;  

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Resets the location'th Point.

 * <p>

 * Rotation Quaternion is assumed to be in the form ( axisX*sinT, axisY*sinT, axisZ*sinT, cosT ).

 *

 * @param location the index of the Point we are setting.

 * @param x New value of its first float.

 */

  public synchronized void setPoint(int location, float x, float y, float z, float w)

    {

    if( location>=0 && location<numPoints )

      {

      curr = vv.elementAt(location);

      if( curr!=null )

        {

        curr.set(x,y,z,w);

        cacheDirty=true;

        }

      }

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Adds a new Static4D to the end of our list of Points to interpolate through.

 * <p>   

 * Only a reference to the Point gets added to the List; this means that one can add a Point 

 * here, and later on {@link Static4D#set(float,float,float,float)} it to some new value and

 * the change will be seamlessly reflected in the interpolated path.  

 * <p>

 * A Point can be added multiple times.

 *   

 * @param v The Point to add.

 */    

  public synchronized void add(Static4D v)

    {

    if( v!=null )

      {

      vv.add(v);

      switch(numPoints)

         {

         case 0: 

         case 1: vc.add(new VectorCacheQuat());

                 vc.add(new VectorCacheQuat());

        	     break;

         default:vc.add(new VectorCacheQuat());

         }

       numPoints++;

       cacheDirty = true;

       }

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Adds a new Static4D to the location'th place in our List of Points to interpolate through.

 *   

 * @param location Index in our List to add the new Point at.

 * @param v The Static4D to add.

 */  

  public synchronized void add(int location, Static4D v)

    {

    if( v!=null )

      {

      vv.add(location, v);

      switch(numPoints)

        {

        case 0: 

        case 1: vc.add(new VectorCacheQuat());

                vc.add(new VectorCacheQuat());

                break;

        default:vc.add(location,new VectorCacheQuat());

        }

      numPoints++;

      cacheDirty = true;

      }

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Removes all occurrences of Point v from the List of Points to interpolate through.  

 * 

 * @param v The Point to remove.

 * @return <code>true</code> if we have removed at least one Point.

 */

  public synchronized boolean remove(Static4D v)

    {

    int n = vv.indexOf(v);

    boolean found = false;

    while( n>=0 ) 

      {

      vv.remove(n);

      switch(numPoints)

        {

        case 0:

        case 1: break;

        case 2: vc.removeAllElements();

                break;

        default:vc.remove(n);

        }

      numPoints--;

      found = true;

      n = vv.indexOf(v);

      }

    if( found ) 

      {

      cacheDirty=true;

      }

    return found;

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Removes a location'th Point from the List of Points we interpolate through.

 * 

 * @param location index of the Point we want to remove. 

 * @return <code>true</code> if location is valid, i.e. if 0<=location&lt;getNumPoints().

 */

  public synchronized boolean remove(int location)

    {

    if( location>=0 && location<numPoints ) 

      {

      vv.removeElementAt(location);

      switch(numPoints)

        {

        case 0: 

        case 1: break;

        case 2: vc.removeAllElements();

                break;

        default:vc.removeElementAt(location);

        }

      numPoints--;

      cacheDirty = true; 

      return true;

      }

    return false;

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Removes all Points.

 */

  public synchronized void removeAll()

    {

    numPoints = 0;

    vv.removeAllElements();

    vc.removeAllElements();

    cacheDirty = false;

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

/**

 * Writes the results of interpolation between the Points at time 'time' to the passed float buffer.

 * Interpolation is done using the spherical linear algorithm, aka SLERP.

 * <p>

 * Since this is a 4-dimensional Dynamic, the resulting interpolated Static4D gets written

 * to four locations in the buffer: buffer[offset], buffer[offset+1], buffer[offset+2] and buffer[offset+3]. 

 * 

 * @param buffer Float buffer we will write the resulting Static4D to.

 * @param offset Offset in the buffer where to write the result.

 * @param time   Time of interpolation. Time=0.0 is the beginning of the first revolution, time=1.0 - the end

 *               of the first revolution, time=2.5 - the middle of the third revolution.

 *               What constitutes 'one revolution' depends on the MODE:

 *               {@link Dynamic#MODE_LOOP}, {@link Dynamic#MODE_PATH} or {@link Dynamic#MODE_JUMP}.

 **/

  synchronized void interpolate(float[] buffer, int offset, float time)

    {  

    switch(numPoints)

      {

      case 0: buffer[offset  ] = 0.0f;

              buffer[offset+1] = 0.0f;

              buffer[offset+2] = 0.0f;

              buffer[offset+3] = 0.0f;

              break;

      case 1: curr = vv.elementAt(0);

              buffer[offset  ] = curr.x; 

              buffer[offset+1] = curr.y;

              buffer[offset+2] = curr.z;

              buffer[offset+3] = curr.w;

              break;

      default:float t = time;

              int vecCurr, segment;

              float scale0, scale1;

              switch(mMode)

                {

                case MODE_LOOP: time = time*numPoints;

                                segment = (int)time;

                                vecCurr = segment;

                                break;

                case MODE_PATH: if( t>0.5f ) t = 1.0f-t;

                                time = 2*t*(numPoints-1);

                                segment = (int)(2*t*(numPoints-1));

                                vecCurr = segment;

                                break;

                case MODE_JUMP: time = time*(numPoints-1);

                                segment = (int)time;

                                vecCurr = segment;

                                break;

                default       : vecCurr = 0;

                                segment = 0;

                }

              if( vecCurr>=0 && vecCurr<numPoints )

                {

                int vecNext = getNext(vecCurr,t);

                curr = vv.elementAt(vecCurr);

                tmp1 = vc.elementAt(vecCurr);

                next = vv.elementAt(vecNext);

                if( cacheDirty ) recomputeCache();  // recompute cache if we have added or remove vectors since last computation

                else if( mSegment!= segment )       // ...or if we have just passed a vector and the vector we are currently flying to has changed

                  {

                  tmp2 = vc.elementAt(vecNext);

                  if( tmp2.vx!=next.x || tmp2.vy!=next.y || tmp2.vz!=next.z || tmp2.vw!=next.w ) recomputeCache();

                  }

                mSegment = segment;

                time = time-vecCurr;

                if( tmp1.sinOmega==0 )

                  {

                  scale0 = 1f;

                  scale1 = 0f;

                  }

                else if( tmp1.cosOmega < 0.99 )

                  {

                  scale0 = (float)Math.sin( (1f-time)*tmp1.omega ) / tmp1.sinOmega;

                  scale1 = (float)Math.sin(     time *tmp1.omega ) / tmp1.sinOmega;

                  }

                else

                  {

                  scale0 = 1f-time;

                  scale1 = time;

                  }

                buffer[offset  ] = scale0*curr.x + scale1*next.x;

                buffer[offset+1] = scale0*curr.y + scale1*next.y;

                buffer[offset+2] = scale0*curr.z + scale1*next.z;

                buffer[offset+3] = scale0*curr.w + scale1*next.w;

                break;

                }

      }

    }  

  }