// circle_tri.java      compile    javac -cp . circle_tri.java
//                      execute    java  -cp . circle_tri circle_tri1.dat
// cover circle with triangles
// Output a Utah graphics .dat file
import java.io.*;
import java.*;
import java.util.*;
import java.text.*;

public class circle_tri
{
  String fileout = "circle_tri.dat";
  int num_points = 0;
  int num_polys = 0;
  double data_points[][] = new double[5000][3]; // x,y,z=0.0
  int data_polys[] = new int[10000]; // 3 pt1 pt2 pt3 
  static int cirpts = 8; // or 16  start with 1
  static int spts = 2*cirpts; // small circle
  static int centpt = spts+cirpts+1;
  double ang = 0.0;
  double Pi = Math.PI;
  double dang = 2.0*Pi/(double)cirpts;
  double hang = 2.0*Pi/(double)spts;
  double iang = 2.0*Pi/(double)spts;
  double x, y, z;
  double r = 1.0;
  double ir = 0.5;

  public circle_tri()
  {
    System.out.println("circle_tri.java running");
    System.out.println("circle_tri.java writing "+fileout);

    ang = 0.0;
    for(int i=0; i<spts; i++) // outer circle
    {
      x = r*Math.cos(ang);
      y = r*Math.sin(ang);
      data_points[i][0] = x; // x
      data_points[i][1] = y; // y
      data_points[i][2] = 0.0; // z unused
      ang = ang + hang;
    }
    num_points = num_points+spts;

    ang = iang;
    for(int i=0; i<cirpts; i++) // inner circle
    {
      x = ir*Math.cos(ang);
      y = ir*Math.sin(ang);
      data_points[i+spts][0] = x; // x
      data_points[i+spts][1] = y; // y
      data_points[i+spts][2] = 0.0; // z unused
      ang = ang + dang;
    }
    num_points = num_points+cirpts;

    data_points[num_points][0] = 0.0; // x center point centpt
    data_points[num_points][1] = 0.0; // y
    data_points[num_points][2] = 0.0; // z unused
    num_points = num_points+1;
    System.out.println("num_points="+num_points);

    for(int j=0; j<spts; j++) // outside triangles
    {
      data_polys[num_polys] = 3;
      data_polys[num_polys+1] = j+1;
      data_polys[num_polys+2] = j+2;
      data_polys[num_polys+3] = spts+1+(j)/2;
      if(j==spts-1)
      {
        data_polys[num_polys+2] = 1;
      }
      num_polys = num_polys+4;
    }

    for(int j=0; j<cirpts; j++) // between outside triangles
    {
      data_polys[num_polys] = 3;
      data_polys[num_polys+1] = 2*j+1;
      data_polys[num_polys+2] = spts+j+1;
      data_polys[num_polys+3] = spts+j;
      if(j==0)
      {
        data_polys[num_polys+3] = spts;
      }
      num_polys = num_polys+4;
    }

    for(int j=0; j<cirpts; j++) // inside triangles
    {
      data_polys[num_polys] = 3;
      data_polys[num_polys+1] = spts+j+1;
      data_polys[num_polys+2] = spts+j+2;
      data_polys[num_polys+3] = centpt;
      if(j==cirpts-1)
      {
        data_polys[num_polys+2] = spts+1;
      }
      num_polys = num_polys+4;
    }

    num_polys = num_polys/4; // not data_polys index
    new datwrite(fileout, data_points, num_points, data_polys, num_polys);
    triwrite("circle_tri", data_polys, num_polys);
    coordwrite("circle_tri", data_points, num_points);
    boundwrite("circle_tri");

    System.out.println("circle_tri.java wrote "+fileout+
                       "  circle_tri.tri"+"  circle_tri.coord");
  } // end circle_tri

  void triwrite(String filename, int data_polys[], int num_polys)
  {
    int k, pt, pts;
    String filetri = filename+".tri";

    try
    {
      BufferedWriter out = new BufferedWriter(new FileWriter(filetri));
      PrintWriter File_out = new PrintWriter(out);

      System.out.println("opened "+filetri+" for writing");
      // use num_polys to write out triangles 
      System.out.println("write num_polys="+num_polys);
      k = 0;
      for(int i=0; i<num_polys; i++)
      {
        pts = data_polys[k++];
        for(int j=0; j<pts; j++)
        {
          pt = data_polys[k++];
          File_out.print(" "+pt);
        }
        File_out.println(" ");
      }
      File_out.close();
    } // end try
    catch(IOException exception)
    {
      System.out.println("triwrite.java "+exception);
    }
    System.out.println("triwrite finished writing "+filetri);
  } // end triwrite


  void coordwrite(String filename, double data_points[][], int num_points)
  {
    int k, pt, pts;
    String filecoord = filename+".coord";
    try
    {
      BufferedWriter out = new BufferedWriter(new FileWriter(filecoord));
      PrintWriter File_out = new PrintWriter(out);

      System.out.println("opened "+filecoord+" for writing");
      for(int i=0; i<num_points; i++)
      {
	File_out.println(data_points[i][0]+" "+data_points[i][1]+" ");
      }
      File_out.close();
    } // end try
    catch(IOException exception)
    {
      System.out.println("coordwrite.java "+exception);
    }
    System.out.println("coordwrite.java finished writing "+filecoord);
  } // end coordwrite

  void boundwrite(String filename)
  {
    String filebound = filename+".bound";

    try
    {
      BufferedWriter out = new BufferedWriter(new FileWriter(filebound));
      PrintWriter File_out = new PrintWriter(out);

      System.out.println("opened "+filebound+" for writing");
      System.out.println("write spts="+spts);
      for(int i=0; i<spts; i++)
      {
	if(i==spts-1)
	{
	  File_out.print(" "+spts+" "+1);
          File_out.println(" ");
	}
	else
        {
	  File_out.print(" "+(i+1)+" "+(i+2));
          File_out.println(" ");
	}
      }
      File_out.close();
    } // end try
    catch(IOException exception)
    {
      System.out.println("boundwrite.java "+exception);
    }
    System.out.println("boundwrite finished writing "+filebound);
  } // end boundwrite

  public static void main (String[] args)
  {
      new circle_tri();
  }
} // end circle_tri.java