Distorted Android

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

// Copyright 2020 Leszek Koltunski  leszek@koltunski.pl                                          //

//                                                                                               //

// This file is part of Distorted.                                                               //

//                                                                                               //

// 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA                //

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

package org.distorted.library.mesh;

import org.distorted.library.main.DistortedLibrary;

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

/**

 * Create a polygon of any shape and varying elevations from the edges towards the center.

 * <p>

 * Specify a list of vertices. Any two adjacent vertices + the center (0,0,0) form a triangle. The

 * polygon is going to be split into such triangles, and each triangle is split into adjustable number

 * of 'bands' form the outer edge towards the center. Edges of each band can can at any elevation.

 */

public class MeshPolygon extends MeshBase

  {

  private static final int NUM_CACHE = 20;

  private float[] mPolygonVertices;

  private int mNumPolygonVertices;

  private float[] mPolygonBands;

  private int mNumPolygonBands;

  private int remainingVert;

  private int numVertices;

  private int extraBand, extraVertices;

  private float[] mCurveCache;

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

// polygonVertices>=3 , polygonBands>=2

  private void computeNumberOfVertices()

     {

     if( mNumPolygonBands==2 && extraBand>0 )

       {

       numVertices = 1 + 2*mNumPolygonVertices*(1+extraBand+2*extraVertices);

       }

     else

       {

       numVertices = (mNumPolygonVertices*mNumPolygonBands+2)*(mNumPolygonBands-1) - 1;

       numVertices+= 2*mNumPolygonVertices*(2*extraBand*extraVertices);

       }

     remainingVert = numVertices;

     }

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

  private void computeCache()

    {

    mCurveCache = new float[NUM_CACHE];

    float[] tmpD = new float[mNumPolygonBands+1];

    float[] tmpX = new float[mNumPolygonBands+1];

    for(int i=1; i<mNumPolygonBands; i++)

      {

      tmpD[i] = (mPolygonBands[2*i-1]-mPolygonBands[2*i+1]) / (mPolygonBands[2*i]-mPolygonBands[2*i-2]);

      tmpX[i] = 1.0f - (mPolygonBands[2*i]+mPolygonBands[2*i-2])/2;

      }

    tmpD[0] = tmpD[1];

    tmpD[mNumPolygonBands] = tmpD[mNumPolygonBands-1];

    tmpX[0] = 0.0f;

    tmpX[mNumPolygonBands] = 1.0f;

    int prev = 0;

    int next = 0;

    for(int i=0; i<NUM_CACHE-1; i++)

      {

      float x = i/(NUM_CACHE-1.0f);

      if( x>=tmpX[next] )

        {

        prev = next;

        while( next<=mNumPolygonBands && x>=tmpX[next] ) next++;

        }

      if( next>prev )

        {

        float t = (x-tmpX[prev]) / (tmpX[next]-tmpX[prev]);

        mCurveCache[i] = t*(tmpD[next]-tmpD[prev]) + tmpD[prev];

        }

      else

        {

        mCurveCache[i] = tmpD[next];

        }

      }

    mCurveCache[NUM_CACHE-1] = tmpD[mNumPolygonBands];

    }

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

  private float getSpecialQuot(int index)

    {

    int num = 1 + extraBand + 2*extraVertices;

    int change1 = extraVertices+1;

    int change2 = num-change1;

    float quot = 1.0f/(extraBand+1);

    if( index<change1 )      return index*quot/change1;

    else if( index>change2 ) return 1-quot + (index-change2)*quot/change1;

    else                     return (index-change1+1)*quot;

    }

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

  private float getQuot(int index, int band, boolean isExtra)

    {

    int num = mNumPolygonBands-1-band;

    if( num>0 )

      {

      if( isExtra )

        {

        int extra = extraBand-band+extraVertices;

        if( index < extra )

          {

          float quot = ((float)extraBand-band)/(extra*num);

          return index*quot;

          }

        else if( index > num+2*extraVertices-extra )

          {

          float quot = ((float)extraBand-band)/(extra*num);

          return (1.0f-((float)extraBand-band)/num) + (index-num-2*extraVertices+extra)*quot;

          }

        else

          {

          return ((float)(index-extraVertices))/num;

          }

        }

      return (float)index/num;

      }

    return 1.0f;

    }

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

  private float derivative(float x)

    {

    if( x>=1.0f )

      {

      return 0.0f;

      }

    else

      {

      float tmp = x*(NUM_CACHE-1);

      int i1 = (int)tmp;

      int i2 = i1+1;

      // why 0.5? Arbitrarily; this way the cubit faces of Twisty Puzzles

      // [the main and only user of this class] look better.

      return 0.5f*((tmp-i1)*(mCurveCache[i2]-mCurveCache[i1]) + mCurveCache[i1]);

      }

    }

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

  private int addVertex(int vertex, int polyBand, int polyVertex, int polyEndVer, float quot,

                        float[] attribs1, float[] attribs2)

    {

    remainingVert--;

    float Xfirst= mPolygonVertices[2*polyVertex  ];

    float Yfirst= mPolygonVertices[2*polyVertex+1];

    float Xlast = mPolygonVertices[2*polyEndVer  ];

    float Ylast = mPolygonVertices[2*polyEndVer+1];

    float xEdge = Xfirst + quot*(Xlast-Xfirst);

    float yEdge = Yfirst + quot*(Ylast-Yfirst);

    float q = mPolygonBands[2*polyBand];

    float x = q*xEdge;

    float y = q*yEdge;

    float z = mPolygonBands[2*polyBand+1];

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB  ] = x;

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB+1] = y;

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB+2] = z;

    float d = derivative(1-mPolygonBands[2*polyBand]);

    float vx = d*xEdge;

    float vy = d*yEdge;

    float vz = xEdge*xEdge + yEdge*yEdge;

    float len = (float)Math.sqrt(vx*vx + vy*vy + vz*vz);

    int index = VERT1_ATTRIBS*vertex + NOR_ATTRIB;

    attribs1[index  ] = vx/len;

    attribs1[index+1] = vy/len;

    attribs1[index+2] = vz/len;

    attribs2[VERT2_ATTRIBS*vertex + TEX_ATTRIB  ] = x+0.5f;

    attribs2[VERT2_ATTRIBS*vertex + TEX_ATTRIB+1] = y+0.5f;

    return vertex+1;

    }

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

  private int createBandStrip(int vertex, int polyBand, int polyVertex, float[] attribs1, float[] attribs2)

    {

    if( polyVertex==0 )

      {

      vertex = addVertex(vertex,polyBand,0,1,0,attribs1,attribs2);

      if( polyBand>0 ) vertex = addVertex(vertex,polyBand,0,1,0,attribs1,attribs2);

      }

    boolean specialCase = mNumPolygonBands==2 && polyBand==0 && extraBand>0;

    boolean isExtra = polyBand<extraBand;

    int numPairs = specialCase ? extraBand+1 : mNumPolygonBands-1-polyBand;

    if( isExtra ) numPairs += 2*extraVertices;

    int polyEndVer = polyVertex==mNumPolygonVertices-1 ? 0 : polyVertex+1;

    float quot1, quot2;

    for(int index=0; index<numPairs; index++)

      {

      if( specialCase )

        {

        quot1 = 1.0f;

        quot2 = getSpecialQuot(index+1);

        }

      else

        {

        quot1 = getQuot(index  ,polyBand+1, isExtra);

        quot2 = getQuot(index+1,polyBand  , isExtra);

        }

      vertex = addVertex(vertex,polyBand+1,polyVertex,polyEndVer,quot1,attribs1,attribs2);

      vertex = addVertex(vertex,polyBand  ,polyVertex,polyEndVer,quot2,attribs1,attribs2);

      }

    return vertex;

    }

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

  private void buildGrid(float[] attribs1, float[] attribs2)

    {

    int vertex=0;

    for(int polyBand=0; polyBand<mNumPolygonBands-1; polyBand++)

      for(int polyVertex=0; polyVertex<mNumPolygonVertices; polyVertex++)

        vertex = createBandStrip(vertex,polyBand,polyVertex,attribs1,attribs2);

    }

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

// PUBLIC API

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

/**

 * Create a polygon of any shape and varying elevations from the edges towards the center.

 * Optionally make it more dense at the vertices.

 *

 * @param verticesXY 2N floats - packed description of polygon vertices. N pairs (x,y).

 *                   Vertices HAVE TO be specified in a COUNTERCLOCKWISE order (starting from any).

 * @param bands      2K floats; K pairs of two floats each describing a single band.

 *                   From (1.0,Z[0]) (outer edge, its Z elevation) to (0.0,Z[K]) (the center,

 *                   its elevation). The polygon is split into such concentric bands.

 *                   Must be band[2*i] > band[2*(i+1)] !

 * @param exBand     This and the next parameter describe how to make the mesh denser at the

 *                   polyVertices. If e.g. exIndex=3 and exVertices=2, then 3 triangles of the

 *                   outermost band (and 2 triangles of the next band, and 1 triangle of the third

 *                   band) get denser - the 3 triangles become 3+2 = 5.

 * @param exVertices See above.

 * @param centerX    the X coordinate of the 'center' of the Polygon, i.e. point of the mesh

 *                   all bands go to.

 * @param centerY    Y coordinate of the center.

 */

  public MeshPolygon(float[] verticesXY, float[] bands, int exBand, int exVertices, float centerX, float centerY)

    {

    super();

    mPolygonVertices   = verticesXY;

    mPolygonBands      = bands;

    mNumPolygonVertices= mPolygonVertices.length /2;

    mNumPolygonBands   = mPolygonBands.length /2;

    extraBand          = exBand;

    extraVertices      = exVertices;

    if( centerX!=0.0f || centerY!=0.0f )

      {

      for(int v=0; v<mNumPolygonVertices; v++)

        {

        mPolygonVertices[2*v  ] -= centerX;

        mPolygonVertices[2*v+1] -= centerY;

        }

      }

    computeNumberOfVertices();

    computeCache();

    float[] attribs1= new float[VERT1_ATTRIBS*numVertices];

    float[] attribs2= new float[VERT2_ATTRIBS*numVertices];

    buildGrid(attribs1,attribs2);

    if( remainingVert!=0 )

      DistortedLibrary.logMessage("MeshPolygon: remainingVert " +remainingVert );

    if( centerX!=0.0f || centerY!=0.0f )

      {

      for(int v=0; v<numVertices; v++)

        {

        attribs1[VERT1_ATTRIBS*v + POS_ATTRIB  ] += centerX;

        attribs1[VERT1_ATTRIBS*v + POS_ATTRIB+1] += centerY;

        attribs2[VERT2_ATTRIBS*v + TEX_ATTRIB  ] += centerX;

        attribs2[VERT2_ATTRIBS*v + TEX_ATTRIB+1] += centerY;

        }

      }

    setAttribs(attribs1,attribs2);

    }

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

  public MeshPolygon(float[] verticesXY, float[] bands, int exIndex, int exVertices)

    {

    this(verticesXY,bands,exIndex,exVertices,0.0f,0.0f);

    }

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

/**

 * Create a polygon of any shape and varying elevations from the edges towards the center.

 * Equivalent of the previous with exIndex=0 or exVertices=0.

 */

  public MeshPolygon(float[] verticesXY, float[] bands)

    {

    this(verticesXY,bands,0,0,0.0f,0.0f);

    }

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

/**

 * Copy constructor.

 */

  public MeshPolygon(MeshPolygon mesh, boolean deep)

    {

    super(mesh,deep);

    }

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

/**

 * Copy the Mesh.

 *

 * @param deep If to be a deep or shallow copy of mVertAttribs1, i.e. the array holding vertices,

 *             normals and inflates (the rest, in particular the mVertAttribs2 containing texture

 *             coordinates and effect associations, is always deep copied)

 */

  public MeshPolygon copy(boolean deep)

    {

    return new MeshPolygon(this,deep);

    }

 }