Distorted Android

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

// Copyright 2020 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/>.                            //

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

package org.distorted.library.mesh;

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

/**

 * 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 triange 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 float[] mPolygonVertices;

  private int mNumPolygonVertices;

  private float[] mPolygonBands;

  private int mNumPolygonBands;

  private int remainingVert;

  private int numVertices;

  private float[] mBandQuot;

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

// polygonVertices>=3 , polygonBands>=2

  private void computeNumberOfVertices(int numPolygonVertices, int numPolygonBands)

     {

     numVertices = (numPolygonVertices*numPolygonBands+2)*(numPolygonBands-1) - 1;

     remainingVert = numVertices;

     }

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

  private void computeCache()

    {

    mBandQuot = new float[mNumPolygonBands];

    int next, prev;

    for(int band=0; band<mNumPolygonBands; band++)

      {

      next = (band==mNumPolygonBands-1 ? band : band+1);

      prev = (band==                 0 ? band : band-1);

      mBandQuot[band] = (mPolygonBands[2*prev+1]-mPolygonBands[2*next+1]) / (mPolygonBands[2*next]-mPolygonBands[2*prev]);

      }

    }

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

  private int addVertex(int vertex, int polyBand, int polyVertex, int polyEndVer, int index, float[] attribs1, float[] attribs2)

    {

    remainingVert--;

    float quot = polyBand<mNumPolygonBands-1 ? (float)index / (mNumPolygonBands-1-polyBand) : 1.0f;

    float vx,vy,vz;

    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 x = mPolygonBands[2*polyBand]*xEdge;

    float y = mPolygonBands[2*polyBand]*yEdge;

    if( quot==0.0f || quot==1.0f )

      {

      vx = mBandQuot[polyBand]*xEdge;

      vy = mBandQuot[polyBand]*yEdge;

      vz = xEdge*xEdge + yEdge*yEdge;

      }

    else

      {

      vx = mBandQuot[polyBand]*(Ylast-Yfirst);

      vy = mBandQuot[polyBand]*(Xfirst-Xlast);

      float tmp = Xfirst*Ylast - Xlast*Yfirst;

      vz = (tmp<0 ? -tmp:tmp);

      }

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

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB  ] = x;

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

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB+2] = mPolygonBands[2*polyBand+1];

    attribs1[VERT1_ATTRIBS*vertex + NOR_ATTRIB  ] = vx/len;

    attribs1[VERT1_ATTRIBS*vertex + NOR_ATTRIB+1] = vy/len;

    attribs1[VERT1_ATTRIBS*vertex + NOR_ATTRIB+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);

        }

      }

    int numPairs = mNumPolygonBands-1-polyBand;

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

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

      {

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

      vertex = addVertex(vertex,polyBand  ,polyVertex,polyEndVer,index+1,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.

 *

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

 * @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)] !

 */

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

    {

    super();

    mPolygonVertices      = verticesXY;

    mPolygonBands         = bands;

    mNumPolygonVertices   = mPolygonVertices.length /2;

    mNumPolygonBands      = mPolygonBands.length /2;

    computeNumberOfVertices(mNumPolygonVertices,mNumPolygonBands);

    computeCache();

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

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

    buildGrid(attribs1,attribs2);

    if( remainingVert!=0 )

      android.util.Log.d("MeshPolygon", "remainingVert " +remainingVert );

    setAttribs(attribs1,attribs2);

    }

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

/**

 * 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);

    }

 }