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;

/**

 * Creator a triangular mesh divided into 'bands' i.e. strips parallel to one of the sides and

 * and of different elevations.

 * <p>

 * This is a building block for MeshMultigon.

 */

public class MeshBandedTriangle extends MeshBase

  {

  private static final int NUM_CACHE = 20;

  private static final int MODE_UP   = 0;

  private static final int MODE_DOWN = 1;

  private static final int MODE_FLAT = 2;

  private float mLeftX, mLeftY;

  private float mRightX, mRightY;

  private float mTopX, mTopY;

  private float[] mNormL, mNormR;

  private int mMode;

  private float[] mBands;

  private int mNumBands;

  private int remainingVert;

  private int numVertices;

  private int extraIndex, extraVertices;

  private float[] mCurveCache;

  private float mVecX, mVecY;

  private int[] mEdgeShape;

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

// mNumBands>=2

  private void computeNumberOfVertices()

     {

     /*

     if( mNumBands==2 && extraIndex>0 )

       {

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

       }

     else

       {

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

       numVertices+= 2*mNumPolygonVertices*(2*extraIndex*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 + extraIndex + 2*extraVertices;

    int change1 = extraVertices+1;

    int change2 = num-change1;

    float quot = 1.0f/(extraIndex+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 = extraIndex-band+extraVertices;

        if( index < extra )

          {

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

          return index*quot;

          }

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

          {

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

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

          }

        else

          {

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

          }

        }

      return (float)index/num;

      }

    return 1.0f;

    }

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

  private float computeZEdge(float quot)

    {

    if( quot>=1.0f ) return 0.0f;

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

      {

      float curr = mPolygonBands[2*band];

      if( curr<=quot )

        {

        float prev = mPolygonBands[2*band-2];

        float prevH= mPolygonBands[2*band-1];

        float currH= mPolygonBands[2*band+1];

        float A = (prev-quot)/(prev-curr);

        return A*currH + (1-A)*prevH;

        }

      }

    return 0.0f;

    }

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

  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 void figureOutNormalVector2D(int edgeShape, int polyVertex, int polyEndVer, float quot, float xEdge, float yEdge )

    {

    if( edgeShape==SHAPE_DD )

      {

      if( quot<0.5f )

        {

        int p = polyVertex>0 ? polyVertex-1 : mNumPolygonVertices-1;

        int prvShape = mEdgeShape[p];

        switch(prvShape)

          {

          case SHAPE_DD : mVecX = xEdge;

                          mVecY = yEdge;

                          break;

          case SHAPE_UD :

          case SHAPE_DUD: float a = 2*quot;

                          float xCurr= mPolygonVertices[2*polyVertex  ];

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

                          float xPrev= mPolygonVertices[2*p  ];

                          float yPrev= mPolygonVertices[2*p+1];

                          float xVec = xCurr-xPrev;

                          float yVec = yCurr-yPrev;

                          mVecX = a*xEdge + (1-a)*xVec;

                          mVecY = a*yEdge + (1-a)*yVec;

                          break;

          default: throw new RuntimeException("figureOutNormalVector2D: impossible1: "+prvShape);

          }

        }

      else

        {

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

        int nxtShape = mEdgeShape[polyEndVer];

        switch(nxtShape)

          {

          case SHAPE_DD : mVecX = xEdge;

                          mVecY = yEdge;

                          break;

          case SHAPE_DU :

          case SHAPE_DUD: float a = 2-2*quot;

                          float xCurr= mPolygonVertices[2*polyEndVer  ];

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

                          float xNext= mPolygonVertices[2*n  ];

                          float yNext= mPolygonVertices[2*n+1];

                          float xVec = xCurr-xNext;

                          float yVec = yCurr-yNext;

                          mVecX = a*xEdge + (1-a)*xVec;

                          mVecY = a*yEdge + (1-a)*yVec;

                          break;

          default: throw new RuntimeException("figureOutNormalVector2D: impossible2: "+nxtShape);

          }

        }

      }

    else if( edgeShape==SHAPE_UU || (quot>=0.5f && edgeShape==SHAPE_DU) || (quot<0.5f && edgeShape==SHAPE_UD) )

      {

      mVecX = 1;

      mVecY = 0;

      }

    else

      {

      float dx = mPolygonVertices[2*polyVertex  ] - mPolygonVertices[2*polyEndVer  ];

      float dy = mPolygonVertices[2*polyVertex+1] - mPolygonVertices[2*polyEndVer+1];

      if( quot<0.5 )

        {

        mVecX = dx;

        mVecY = dy;

        }

      else

        {

        mVecX = -dx;

        mVecY = -dy;

        }

      }

    }

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

  private float figureOutDerivative(int edgeShape, int polyBand, float quot)

    {

    if( edgeShape==SHAPE_DD )

      {

      return derivative(1-mPolygonBands[2*polyBand]);

      }

    if( edgeShape==SHAPE_UU || (quot>=0.5f && edgeShape==SHAPE_DU) || (quot<0.5f && edgeShape==SHAPE_UD) )

      {

      return 0;

      }

    float x = 1-mPolygonBands[2*polyBand];

    float q = quot>=0.5f ? 2-2*quot : 2*quot;

    return derivative((1-x)*q+x);

    }

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

  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 zEdge;

    float q = mPolygonBands[2*polyBand];

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

    float t = mPolygonBands[2*mNumPolygonBands-1];

    int shape = mEdgeShape[polyVertex];

    switch(shape)

      {

      case SHAPE_DD : zEdge = 0.0f; break;

      case SHAPE_UU : zEdge = t;    break;

      case SHAPE_DU : zEdge = quot>=0.5f ? t : computeZEdge(1-2*quot); break;

      case SHAPE_UD : zEdge = quot<=0.5f ? t : computeZEdge(2*quot-1); break;

      default       : zEdge = quot<=0.5f ? computeZEdge(1-2*quot) : computeZEdge(2*quot-1); break;

      }

    float x = q*xEdge;

    float y = q*yEdge;

    float z = o + (t-o)*(zEdge/t);

    attribs1[VERT1_ATTRIBS*vertex + POS_ATTRIB  ] = x;

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

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

    figureOutNormalVector2D(shape, polyVertex, polyEndVer, quot, xEdge, yEdge);

    float d = figureOutDerivative(shape,polyBand,quot);

    float vx = d*mVecX;

    float vy = d*mVecY;

    float vz = mVecX*mVecX + mVecY*mVecY;

    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 && extraIndex>0;

    boolean isExtra = polyBand<extraIndex;

    int numPairs = specialCase ? extraIndex+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 int computeEdgeShape(int curr)

    {

    if( mEdgeUp==null || !mEdgeUp[curr] ) return SHAPE_DD;

    int prev = (curr==0 ? mNumPolygonVertices-1 : curr-1);

    int next = (curr==mNumPolygonVertices-1 ? 0 : curr+1);

    boolean rd = ( !mEdgeUp[next] || mVertUp==null || !mVertUp[next] );

    boolean ld = ( !mEdgeUp[prev] || mVertUp==null || !mVertUp[curr] );

    return rd ? (ld ? SHAPE_DUD : SHAPE_UD) : (ld ? SHAPE_DU : SHAPE_UU);

    }

*/

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

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

    {

    /*

    int vertex=0;

    mEdgeShape = new int[mNumPolygonVertices];

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

      mEdgeShape[polyVertex] = computeEdgeShape(polyVertex);

    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 triangular mesh split into 'bands' - i.e. strips of triangles - which are parallel to

 * a given edge.

 *

 * @param vL         A pair of floats (x,y) which defines the 'left' vertex of the triangle.

 * @param vR         A pair of floats (x,y) which defines the 'right' vertex of the triangle.

 * @param vT         A pair of floats (x,y) which defines the 'top' vertex of the triangle.

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

 *                   From (1.0,Z[0]) (the 'left-right' edge, its Z elevation) to (0.0,Z[K])

 *                   (the 'top' vertex, its elevation). The polygon is split into such strips.

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

 *                   The way the bands get interpreted also depends on the 'mode' param.

 * @param normL      A pair of floats which define a 2D vector - which is the normal vector of each

 *                   mesh vertex which lies on the 'left-top' edge casted to the XY plane.

 * @param normR      Same as above but about the vertices which belong to the 'right-top' triangle

 *                   edge. This and the previous param define the vector field of normals, as seen

 *                   from above, of the whole mesh.

 * @param mode       MODE_UP, MODE_DOWN or MODE_FLAT.

 *                   This defines how we interpret the bands.

 *                   If UP, we interpret them the same as in MeshPolygon - i.e. the first band is

 *                   about the 'left-right' edge, then progressively towards the 'top'.

 *                   If DOWN, we turn the interpretation of the bands upside-down: it is the last

 *                   band which defines the strip aong the 'left-right' edge.

 *                   If FLAT, everything is flat anyway, so we disregard the bands and return a mesh

 *                   with 3 vertices.

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

 *                   'left' and 'right' vertices. 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.

 */

  public MeshBandedTriangle(float[] vL, float[] vR, float[] vT, float[] bands, float[] normL, float[] normR, int mode, int exIndex, int exVertices)

    {

    super();

    mLeftX   = vL[0];

    mLeftY   = vL[1];

    mRightX  = vR[0];

    mRightY  = vR[1];

    mTopX    = vT[0];

    mTopY    = vT[1];

    mMode = mode;

    mNormL= normL;

    mNormR= normR;

    mBands        = bands;

    mNumBands     = mBands.length /2;

    extraIndex    = exIndex;

    extraVertices = exVertices;

    computeNumberOfVertices();

    computeCache();

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

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

    buildGrid(attribs1,attribs2);

    if( remainingVert!=0 )

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

    setAttribs(attribs1,attribs2);

    }

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

/**

 * Copy constructor.

 */

  public MeshBandedTriangle(MeshBandedTriangle 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 MeshBandedTriangle copy(boolean deep)

    {

    return new MeshBandedTriangle(this,deep);

    }

 }