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library / src / main / java / org / distorted / library / mesh / MeshTriangles.java @ b5be333a

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///////////////////////////////////////////////////////////////////////////////////////////////////
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// Copyright 2020 Leszek Koltunski                                                               //
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//                                                                                               //
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// This file is part of Distorted.                                                               //
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//                                                                                               //
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// Distorted is free software: you can redistribute it and/or modify                             //
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// it under the terms of the GNU General Public License as published by                          //
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// the Free Software Foundation, either version 2 of the License, or                             //
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// (at your option) any later version.                                                           //
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//                                                                                               //
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// Distorted is distributed in the hope that it will be useful,                                  //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of                                //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                                 //
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// GNU General Public License for more details.                                                  //
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//                                                                                               //
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// You should have received a copy of the GNU General Public License                             //
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// along with Distorted.  If not, see <http://www.gnu.org/licenses/>.                            //
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///////////////////////////////////////////////////////////////////////////////////////////////////
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package org.distorted.library.mesh;
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * Create a Mesh which approximates an equilateral triangle.
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 */
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public class MeshTriangles extends MeshBase
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  {
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  private int numVertices;
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  private int remainingVert;
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  private int addVertex(int vertex, float x, float y, float[] attribs)
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     {
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     remainingVert--;
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     attribs[VERT_ATTRIBS*vertex + POS_ATTRIB  ] = x-0.5f;
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     attribs[VERT_ATTRIBS*vertex + POS_ATTRIB+1] = y-0.5f;
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     attribs[VERT_ATTRIBS*vertex + POS_ATTRIB+2] = 0.0f;
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     attribs[VERT_ATTRIBS*vertex + NOR_ATTRIB  ] = 0.0f;
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     attribs[VERT_ATTRIBS*vertex + NOR_ATTRIB+1] = 0.0f;
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     attribs[VERT_ATTRIBS*vertex + NOR_ATTRIB+2] = 1.0f;
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     attribs[VERT_ATTRIBS*vertex + INF_ATTRIB  ] = (x-0.5f);
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     attribs[VERT_ATTRIBS*vertex + INF_ATTRIB+1] = (y-0.5f);
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     attribs[VERT_ATTRIBS*vertex + INF_ATTRIB+2] = 0.01f   ;  // Inflated surface needs to be slightly in front
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     attribs[VERT_ATTRIBS*vertex + TEX_ATTRIB  ] = x;
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     attribs[VERT_ATTRIBS*vertex + TEX_ATTRIB+1] = y;
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     return vertex+1;
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     }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  private void computeNumberOfVertices(int level)
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     {
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     numVertices = level*(level+2);
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     remainingVert = numVertices;
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     }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  private int buildRow(int vertex,float sx, float sy, int length, float dx, float dy, float[] attribs)
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    {
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    for(int i=0; i<length; i++)
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      {
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      vertex = addVertex(vertex, sx   , sy   , attribs);
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      vertex = addVertex(vertex, sx+dx, sy+dy, attribs);
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      sx += 2*dx;
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      }
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    vertex = addVertex(vertex, sx, sy, attribs);
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    return vertex;
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  private void buildGrid(float[] attribs, int level)
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     {
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     float sx = 0.0f;
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     float sy = 0.0f;
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     float dx = 0.5f/level;
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     float dy = 1.0f/level;
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     int vertex = 0;
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     for(int row=level; row>=1; row--)
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       {
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       vertex = buildRow(vertex,sx,sy,row,dx,dy,attribs);
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       sx += 2*dx*(row-0.5f);
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       sy += dy;
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       dx *= -1;
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       }
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     }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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// PUBLIC API
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///////////////////////////////////////////////////////////////////////////////////////////////////
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  /**
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   * Creates the underlying grid of vertices with the usual attribs which approximates an equilateral
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   * triangle.
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   *
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   * @param level Specifies the level of slicing. Valid values: level &ge; 1
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   */
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  public MeshTriangles(int level)
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     {
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     super();
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     computeNumberOfVertices(level);
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     float[] attribs= new float[VERT_ATTRIBS*numVertices];
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     buildGrid(attribs,level);
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     if( remainingVert!=0 )
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       android.util.Log.d("MeshTriangles", "remainingVert " +remainingVert );
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     setAttribs(attribs);
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     }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * deep copy.
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 */
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  public MeshTriangles(MeshTriangles mesh)
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    {
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    super(mesh);
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    }
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///////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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 * deep copy.
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 */
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  public MeshTriangles deepCopy()
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    {
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    return new MeshTriangles(this);
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    }
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  }
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