//
// This example program reads a .binvox file and writes
// a text file (with Java 2-byte characters) version of the same file called "voxels.txt"
//
// 0 = empty voxel
// 1 = filled voxel
// A newline is output after every "dim" voxels (depth = height = width = dim)
//
// Note that this text file format is not supported by "viewvox" and "thinvox"
//
// The x-axis is the most significant axis, then the z-axis, then the y-axis.
//
import java.io.*;





public class ReadBinvox
{
  private static byte[] voxels;
  private static int depth, height, width;
  private static int size;
  private static double tx, ty, tz;
  private static double scale;


  


  public static boolean read_binvox(String filespec) throws Exception
  {
    FileInputStream binvox_file = new FileInputStream(filespec);
    DataInputStream binvox_data = new DataInputStream(binvox_file);
    
    //
    // read header
    //
    String line = binvox_data.readLine();  // deprecated function though
    if (!line.startsWith("#binvox")) {
      System.out.println("Error: first line reads [" + line + "] instead of [#binvox]");
      return false;
    }

    String version_string = line.substring(8);
    int version = Integer.parseInt(version_string);
    System.out.println("reading binvox version " + version);

    depth = height = width = 0;
    boolean done = false;
    
    while(!done) {

      line = binvox_data.readLine();

      if (line.startsWith("data")) done = true;
      else {
	if (line.startsWith("dim")) {
	  String[] dimensions = line.split(" ");
	  depth = Integer.parseInt(dimensions[1]);
	  height = Integer.parseInt(dimensions[2]);
	  width = Integer.parseInt(dimensions[3]);
	}
	else {
	  if (line.startsWith("translate")) {
	    // tx = binvox_data.readDouble();
	    // ty = binvox_data.readDouble();
	    // tz = binvox_data.readDouble();
	  }
	  else {
	    if (line.startsWith("scale")) {
	      // scale = binvox_data.readDouble();
	    }
	    else {
	      System.out.println("  unrecognized keyword [" + line + "], skipping");
	    }
	  }
	}
      }
    }  // while
    
    if (!done) {
      System.out.println("  error reading header");
      return false;
    }
    if (depth == 0) {
      System.out.println("  missing dimensions in header");
      return false;
    }

    size = width * height * depth;
    voxels = new byte[size];

    //
    // read voxel data
    //
    byte value;
    int count;
    int index = 0;
    int end_index = 0;
    int nr_voxels = 0;
  
    // *input >> value;  // read the linefeed char

    while(end_index < size) {

      value = binvox_data.readByte();
      // idiotic Java language doesn't have unsigned types, so we have to use an int for 'count'
      // and make sure that we don't interpret it as a negative number if bit 7 (the sign bit) is on
      count = binvox_data.readByte() & 0xff;

      end_index = index + count;
      if (end_index > size) return false;
      for(int i = index; i < end_index; i++) voxels[i] = value;
	
      if (value > 0) nr_voxels += count;
      index = end_index;
      
    }  // while

    System.out.println("  read " + nr_voxels + " voxels");
    return true;

  }  // read_binvox

  



  public static void main(String[] args) throws Exception
  {
    if (args.length != 1) {
      System.out.println("Usage: read_binvox <binvox filename>");
      System.exit(1);
    }

    if (!read_binvox(args[0])) {
      System.out.println("Error reading [" + args[0] + "]");
      System.exit(1);
    }

    //
    // now write the data to as Java characters
    //
    FileOutputStream out = new FileOutputStream("voxels.txt");
    DataOutputStream data_out = new DataOutputStream(out);
    
    System.out.println("Writing voxel data to a text file [voxels.txt]...");

    data_out.writeChars("#binvox Java character data\n");
    data_out.writeChars("dim ");
    data_out.writeChars(new Integer(depth).toString());  // more Java bloat
    data_out.writeChar(' ');
    data_out.writeChars(new Integer(height).toString());
    data_out.writeChar(' ');
    data_out.writeChars(new Integer(width).toString());
    data_out.writeChars("\n");

    data_out.writeChars("data\n");
    
    for(int i=0; i < size; i++) {
      if (voxels[i] == 1) data_out.writeChar('1');
      else data_out.writeChar('0');
      if (((i + 1) % width) == 0) data_out.writeChars("\n");
    }  // for

    data_out.close();

    System.out.println("done");
    System.out.println();
    
  }  // main
  
	
}  // ReadBinvox class