Distorted Android

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// Copyright 2023 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                //

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package org.distorted.library.mesh;

import java.util.ArrayList;

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/**

 * Create a 'multigon' mesh - a union of several polygons.

 *

 * <p>

 * Specify several lists of vertices. Each list defines one polygon. (@see MeshPolygon).

 * If two such polygons share an edge (or several edges) then the edge in both of them is

 * marked 'up'.

 */

public class MeshMultigon extends MeshBase

  {

  private static final float MAX_ERROR = 0.0001f;

  private float[][] mOuterVertices;

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  private boolean isSame(float dx, float dy)

    {

    return (dx*dx + dy*dy < MAX_ERROR);

    }

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

  private boolean isUp(float[][] vertices, int polygon, int edge)

    {

    //android.util.Log.e("D", "checking polygon "+polygon+" edge "+edge);

    float[] p= vertices[polygon];

    int lenP = p.length/2;

    int len  = vertices.length;

    int next = (edge==lenP-1 ? 0 : edge+1);

    float v1x = p[2*edge  ];

    float v1y = p[2*edge+1];

    float v2x = p[2*next  ];

    float v2y = p[2*next+1];

    //android.util.Log.e("D", " v1="+v1x+" "+v1y+"  v2="+v2x+" "+v2y);

    for(int i=0; i<len; i++)

      if( i!=polygon )

        {

        int num = vertices[i].length/2;

        for(int j=0; j<num; j++)

          {

          int n = (j==num-1 ? 0 : j+1);

          float[] v = vertices[i];

          float x1 = v[2*j  ];

          float y1 = v[2*j+1];

          float x2 = v[2*n  ];

          float y2 = v[2*n+1];

          //android.util.Log.e("D", "comparing v2 to "+x1+" "+y1);

          //android.util.Log.e("D", "comparing v1 to "+x2+" "+y2);

          if( isSame(v2x-x1,v2y-y1) && isSame(v1x-x2,v1y-y2) ) return true;

          }

        }

    //android.util.Log.e("D", "FALSE");

    return false;

    }

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

  private boolean[][] computeEdgesUp(float[][] vertices)

    {

    int num = vertices.length;

    boolean[][] up = new boolean[num][];

    for(int i=0; i<num; i++)

      {

      int len = vertices[i].length/2;

      up[i] = new boolean[len];

      for(int j=0; j<len; j++)

        {

        up[i][j] = isUp(vertices,i,j);

        //android.util.Log.e("D", "polygon "+i+" edge "+j+" up: "+up[i][j]);

        }

      }

    return up;

    }

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

  private float[] detectFirstOuterVertex(float[][] vertices)

    {

    float X = -Float.MAX_VALUE;

    int I=0,J=0, len = vertices.length;

    for(int i=0; i<len; i++ )

      {

      float[] v = vertices[i];

      int num = v.length/2;

      for(int j=0; j<num; j++)

        if(v[2*j]>X)

          {

          X = v[2*j];

          I = i;

          J = j;

          }

      }

    float[] v = vertices[I];

    return new float[] {v[2*J],v[2*J+1]};

    }

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

  private double computeAngle(float x1,float y1, float x2, float y2)

    {

    double diff = Math.atan2(y2,x2)-Math.atan2(y1,x1);

    return diff<0 ? diff+(2*Math.PI) : diff;

    }

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

  private float[] detectNextOuterVertex(float[][] vertices, float[] curr, float[] vect)

    {

    double minAngle = 2*Math.PI;

    float x=0, y=0;

    for( float[] v : vertices )

      {

      int num = v.length/2;

      for( int j=0; j<num; j++)

        {

        float xc = v[2*j];

        float yc = v[2*j+1];

        if( xc==curr[0] && yc==curr[1])

          {

          int n = (j==num-1 ? 0 : j+1);

          float xn = v[2*n];

          float yn = v[2*n+1];

          double angle = computeAngle(vect[0], vect[1], xn-xc, yn-yc);

          if (angle < minAngle)

            {

            minAngle = angle;

            x = xn;

            y = yn;

            }

          break;

          }

        }

      }

    return new float[] {x,y};

    }

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

  private void computeOuter(float[][] vertices)

    {

    ArrayList<float[]> tmp = new ArrayList<>();

    float[] vect = new float[] {1,0};

    float[] first= detectFirstOuterVertex(vertices);

    float[] next = first;

    do

      {

      float[] prev = next;

      next = detectNextOuterVertex(vertices,next,vect);

      vect[0] = prev[0]-next[0];

      vect[1] = prev[1]-next[1];

      tmp.add(next);

      }

    while( next[0]!=first[0] || next[1]!=first[1] );

    int num = tmp.size();

    mOuterVertices = new float[num][];

    for(int i=0; i<num; i++) mOuterVertices[i] = tmp.remove(0);

    }

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

  private boolean doesntBelongToOuter(float x, float y)

    {

    for( float[] v : mOuterVertices )

      if( x==v[0] && y==v[1] ) return false;

    return true;

    }

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

  private boolean[][] computeVertsUp(float[][] vertices)

    {

    computeOuter(vertices);

    int num = vertices.length;

    boolean[][] up = new boolean[num][];

    for(int i=0; i<num; i++)

      {

      float[] v = vertices[i];

      int len = v.length/2;

      up[i] = new boolean[len];

      for(int j=0; j<len; j++) up[i][j] = doesntBelongToOuter(v[2*j],v[2*j+1]);

      }

    return up;

    }

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

// PUBLIC API

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

/**

 * Specify several lists of vertices. Each list defines one polygon. (@see MeshPolygon).

 * If two such polygons share an edge (or several edges) then the edge in both of them is

 * marked 'up'.

 *

 * @param vertices   an array of arrays, each specifying vertices of a single polygon.

 * @param band       see MeshPolygon. Shared among all polygons.

 * @param exIndex    see MeshPolygon. Shared among all polygons.

 * @param exVertices see MeshPolygon. Shared among all polygons.

 * @param centers    for each polygon, coordinates of its center.

 */

  public MeshMultigon(float[][] vertices, float[] band, int exIndex, int exVertices, float[][] centers)

    {

    super();

    int numPolygons = vertices.length;

    MeshPolygon[] meshes = new MeshPolygon[numPolygons];

    boolean[][] edgesUp = computeEdgesUp(vertices);

    boolean[][] vertsUp = computeVertsUp(vertices);

    for(int i=0; i<numPolygons; i++)

      meshes[i] = new MeshPolygon(vertices[i],band,edgesUp[i],vertsUp[i],exIndex,exVertices,centers[i][0],centers[i][1]);

    join(meshes);

    mergeEffComponents();

    mergeTexComponents();

    }

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

/**

 * Auto-create the centers to be the centers of gravity of each polygon.

 */

  public MeshMultigon(float[][] vertices, float[] band, int exIndex, int exVertices)

    {

    super();

    int numPolygons = vertices.length;

    MeshPolygon[] meshes = new MeshPolygon[numPolygons];

    boolean[][] edgesUp = computeEdgesUp(vertices);

    boolean[][] vertsUp = computeVertsUp(vertices);

    for(int i=0; i<numPolygons; i++)

      {

      float[] v = vertices[i];

      int num = v.length/2;

      float xsum=0, ysum = 0;

      for(int j=0; j<num; j++)

        {

        xsum += v[2*j];

        ysum += v[2*j+1];

        }

      meshes[i] = new MeshPolygon(v,band,edgesUp[i],vertsUp[i],exIndex,exVertices,xsum/num,ysum/num);

      }

    join(meshes);

    mergeEffComponents();

    mergeTexComponents();

    }

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

/**

 * Copy constructor.

 */

  public MeshMultigon(MeshMultigon 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 MeshMultigon copy(boolean deep)

    {

    return new MeshMultigon(this,deep);

    }

 }