Sample code for arrays


package com.ai.android.OpenGL.SDK15;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import android.util.Log;

public class EvenPolygon 
{
   private float cx, cy, cz, r;
   private int sides;
   private float[] xarray = null;
   private float[] yarray = null;
   
   public EvenPolygon(float incx, float incy, float incz, // (x,y,z) center 
         float inr, // radius 
         int insides) // number of sides
   {
      cx = incx;
      cy = incy;
      cz = incz;
      r = inr;
      sides = insides;
      
      xarray = new float[sides];
      xarray = new float[sides];
      calcArrays();
   }
   private void calcArrays()
   {
      float[] xmarray = this.getXMultiplierArray();
      float[] ymarray = this.getYMultiplierArray();
      
      //calc xarray
      for(int i=0;i<sides-1;i++)
      {
         float curm = xmarray[i];
         float xcoord = cx + r * curm;
         xarray[i] = xcoord;
      }
      this.printArray(xarray, "xarray");
      
      //calc yarray
      for(int i=0;i<sides-1;i++)
      {
         float curm = ymarray[i];
         float ycoord = cy + r * curm;
         yarray[i] = ycoord;
      }
      this.printArray(yarray, "yarray");
      
   }
   public FloatBuffer getVertexBuffer()
   {
       int vertices = sides + 1;
       int coordinates = 3;
       int floatsize = 4;
       int spacePerVertex = coordinates * floatsize;
       
        ByteBuffer vbb = ByteBuffer.allocateDirect(spacePerVertex * vertices);
        vbb.order(ByteOrder.nativeOrder());
        FloatBuffer mFVertexBuffer = vbb.asFloatBuffer();
        
        //Put the first coordinate (x,y,z:0,0,0)
        mFVertexBuffer.put(0.0f); //x
        mFVertexBuffer.put(0.0f); //y
        mFVertexBuffer.put(0.0f); //z
        
        for (int i=0;i<sides-1;i++)
        {
            mFVertexBuffer.put(xarray[i]); //x
            mFVertexBuffer.put(yarray[i]); //y
            mFVertexBuffer.put(0.0f); //z
        }
      return mFVertexBuffer;
   }
   public ShortBuffer getIndexBuffer()
   {
        ByteBuffer ibb = ByteBuffer.allocateDirect(sides * 3 * 2);
        ibb.order(ByteOrder.nativeOrder());
        ShortBuffer mIndexBuffer = ibb.asShortBuffer();
        for (int i=0;i<sides;i++)
        {
           short index1 = 0;
           short index2 = (short)(i+1);
           short index3 = (short)((i+2)%sides);
           mIndexBuffer.put(index1);
           mIndexBuffer.put(index2);
           mIndexBuffer.put(index3);
        }
        return mIndexBuffer;
   }
   private float[] getXMultiplierArray()
   {
      float[] angleArray = getAngleArrays();
      float[] xmultiplierArray = new float[sides];
      for(int i=0;i<angleArray.length;i++)
      {
         float curAngle = angleArray[i];
         float sinvalue = (float)Math.cos(Math.toRadians(curAngle));
         float absSinValue = Math.abs(sinvalue);
         if (isXPositiveQuadrant(curAngle))
         {
            sinvalue = absSinValue;
         }
         else
         {
            sinvalue = -absSinValue;
         }
         xmultiplierArray[i] = this.getApproxValue(sinvalue);
      }
      this.printArray(xmultiplierArray, "xmultiplierArray");
      return xmultiplierArray;
   }
   
   private float[] getYMultiplierArray()
   {
      float[] angleArray = getAngleArrays();
      float[] ymultiplierArray = new float[sides];
      for(int i=0;i<angleArray.length;i++)
      {
         float curAngle = angleArray[i];
         float sinvalue = (float)Math.sin(Math.toRadians(curAngle));
         float absSinValue = Math.abs(sinvalue);
         if (isYPositiveQuadrant(curAngle))
         {
            sinvalue = absSinValue;
         }
         else
         {
            sinvalue = -absSinValue;
         }
         ymultiplierArray[i] = this.getApproxValue(sinvalue);
      }
      this.printArray(ymultiplierArray, "ymultiplierArray");
      return ymultiplierArray;
   }
   
   private boolean isXPositiveQuadrant(float angle)
   {
      if ((0 <= angle) && (angle <= 90))
      {
         return true;
      }
      
      if ((angle < 0) && (angle >= -90))
      {
         return true;
      }
      return false;
   }
   
   private boolean isYPositiveQuadrant(float angle)
   {
      if ((0 <= angle) && (angle <= 90))
      {
         return true;
      }
      
      if ((angle < 180) && (angle >= 90))
      {
         return true;
      }
      return false;
   }
   private float[] getAngleArrays()
   {
      float[] angleArray = new float[sides];
      float commonAngle = 360.0f/sides;
      float halfAngle = commonAngle/2.0f;
      float firstAngle = 360.0f - (90+halfAngle);
      angleArray[0] = firstAngle;
      
      float curAngle = firstAngle;
      for(int i=1;i<sides;i++)
      {
         float newAngle = curAngle - commonAngle;
         angleArray[i] = newAngle;
         curAngle = newAngle;
      }
      printArray(angleArray, "angleArray");
      return angleArray;
   }
   private float getApproxValue(float f)
   {
      if (Math.abs(f) < 0.001)
      {
         return 0;
      }
      return f;
   }
   public static void test()
   {
      EvenPolygon triangle = new EvenPolygon(0,0,0,1,3);
   }
   private void printArray(float array[], String tag)
   {
      StringBuilder sb = new StringBuilder(tag);
      for(int i=0;i<array.length;i++)
      {
         sb.append(";").append(array[i]);
      }
      Log.d("hh",sb.toString());
   }
}