/**
 * File: CheckerboardGenerator.java
 * Author: Marsette Vona
 * Created: 4/7/10
 **/

import java.io.*;
import static java.lang.Math.*;

/**
 * <p>This program generates a checkerboard base plane in a format compatible
 * with CS4300 Homework 6: a ray tracer.</p>
 *
 * <p>The output is a white plane through the world frame origin perpendicular
 * to the world frame y axis, overlaid by a black checkerboard pattern.  The
 * checkerboard pattern extends from -width/2 to +width/2 in world frame units
 * along the x axis, and from -height/2 to +height/2 in world frame units along
 * the z axis.  There are nx columns and nz rows.</p>
 *
 * <p>To compile: javac CheckerboardGenerator.java</p>
 *
 * <p>To generate doc: javadoc -d doc CheckerboardGenerator.java</p>
 *
 * <p>To run: java CheckerboardGenerator nx nz width height
 * [firstVertexIndex]</p>
 *
 * <p>Note: this code may require Java 1.6 or greater.</p>
 *
 * <p>See <a href="http://www.ccs.neu.edu/course/cs4300/HW6/HW6.html">the
 * assignment</a> for the output format.</p>
 **/
public class CheckerboardGenerator {

  /** base plane material color greylevels **/
  public static final double BASE_AI = 0.8, BASE_DI = 0.5, BASE_SI = 0.1;

  /** base plane material colors **/
  public static final double[]
  BASE_AM = grey(BASE_AI), BASE_DM = grey(BASE_DI), BASE_SM = grey(BASE_SI);

  /** phong exponent for base plane **/
  public static final int BASE_PHONG_EXP = 1;

  /** check material color greylevels **/
  public static final double CHECK_AI = 0.0, CHECK_DI = 0.0, CHECK_SI = 0.1;

  /** check material colors **/
  public static final double[]
  CHECK_AM = grey(CHECK_AI),
    CHECK_DM = grey(CHECK_DI),
    CHECK_SM = grey(CHECK_SI);

  /** phong exponent for checks **/
  public static final int CHECK_PHONG_EXP = 1;

  /** y offset of checks **/
  public static final double CHECK_OFFSET = 0.001;

  /** vertex component indices **/
  public static final int X = 0, Y = 1, Z = 2;

  /** next vertex index to be printed **/
  protected static int nextVertex = 0;

  /** see class header doc **/
  public static void main(String[] arg) throws NumberFormatException {

    if (arg.length < 4) {
      System.err.println(
        "usage: java CheckerboardGenerator nx nz width height "+
        "[firstVertexIndex]");
      System.exit(1);
    }

    int nx = Integer.parseInt(arg[0]);
    int nz = Integer.parseInt(arg[1]);
    double w = Double.parseDouble(arg[2]);
    double h = Double.parseDouble(arg[3]);

    if (arg.length > 4) nextVertex = Integer.parseInt(arg[4]);

    //the white plane
    System.out.println("am "+string(BASE_AM));
    System.out.println("dm "+string(BASE_DM));
    System.out.println("sm "+string(BASE_SM)+" "+BASE_PHONG_EXP);
    System.out.println("ps "+printVertex(new double[] {0.0, 0.0, 0.0}));

    //the checks

    System.out.println("am "+string(CHECK_AM));
    System.out.println("dm "+string(CHECK_DM));
    System.out.println("sm "+string(CHECK_SM)+" "+CHECK_PHONG_EXP);

    double cw = w/((double) nx), ch = h/((double) nz);
    double[] v = new double[3];
    v[Y] = CHECK_OFFSET;
    int a, b, c;
    for (int i = 0; i < nz; i++) {
      for (int j = 0; j < nx; j++) {
        if ((i%2)==(j%2)) {
          v[X] = -w/2+j*cw; v[Z] = -h/2+i*ch; a = printVertex(v);
          v[Z] += ch; b = printVertex(v);
          v[X] += cw; c = printVertex(v);
          System.out.println("ts "+a+" "+b+" "+c);
          b = a; a = c; c = b; //swap a and c
          v[Z] -= ch; b = printVertex(v);
          System.out.println("ts "+a+" "+b+" "+c);
        }
      }
    }
  }

  /** returns a grey color **/
  public static double[] grey(double intensity) {
    return new double[] {intensity, intensity, intensity};
  }

  /** converts <i>v</i> to a string **/
  public static String string(double[] v) {
    return v[X]+" "+v[Y]+" "+v[Z];
  }

  /** print a vertex **/
  public static int printVertex(double[] v) {
    System.out.println("vv "+string(v)+" 0 1 0");
    return nextVertex++;
  }
}