/** Air Navigation Waypoint Intercept Demonstrator
    by Robert J Morton 21 Oct 1997*/

/*  Plots the encounter on a 350 by 200 colour raster which is displayed 
    by the applet class WayPtApp.class */

import java.awt.Color;

class wpcolour {  // Waypoint Colour Array

  double
    Pi = Math.PI,  //the circular constant
    TwoPi = Pi + Pi,
    PiBy2 = Pi / 2;

  int
    XW = 330,  // x-width: horizontal width of tracking area
    YH = 200;  // y-height: vertical height of tracking area

  Color
    BGC,                // background colour of track area
    ATC = Color.white,  // aircraft track colour
    SRC,                // selected radial colour
    GCC,                // green circle colour
    RCC,                // red circle colour
   r C[][];             // to store the picture so far


  wpcolour() {  //CONSTRUCTOR
    C = new Color[XW][YH];  // create the tracking area array

    GCC = new java.awt.Color(0,255,72);  // special bright green for circle
    RCC = new java.awt.Color(255,0,72);  // special bright red for circle
    BGC = new java.awt.Color(0,0,160);   // special browny-green for axes
    SRC = new java.awt.Color(0,192,192); // special cyan for selected radial
  } 


  // DRAW APPROACH CONSTRUCTS ON THE DISPLAY RASTER
  void InitC(aircraft ac, waypoint wp, double OSR) {
    int i, j;
    for(i = 0 ; i < XW ; i++)    // Set all pixels in the tracking
      for(j = 0 ; j < YH ; j++)  // square to background colour.
        C[i][j] = BGC;

    // DRAW RED AND GREEN GUIDE CIRCLES
    double
    // radius of right-hand guide circle perpendicular to selected radial
      a = OSR + PiBy2,

    /* Co-ordinates of centre of right-hand guide circle
    expressed as displacements from the waypoint. */

      xr = ac.r * Math.sin(a),
      yr = ac.r * Math.cos(a);

    // radius of left-hand guide circle/ perpendicular to selected radial
    a = OSR - PiBy2;

    /* Co-ordinates of centre of left-hand guide circle
    expressed as displacements from the waypoint. */
    double
      xl = ac.r * Math.sin(a),
      yl = ac.r * Math.cos(a),
      x, y;

    // for every degree round a guide circle...
    for (a = 0; a <= TwoPi; a += .017453292) {

      /* Absolute co-ordinates of one point on a generic
      guide circle which is centred on the waypoint.*/

      x = wp.X + ac.r * Math.sin(a);
      y = wp.Y + ac.r * Math.cos(a);

      // bias to right-hand circle and plot a green dot
      C[(int)(xr + x)][(int)(yr + y)] = GCC;

      // bias to left-hand circle and plot a red dot
      C[(int)(xl + x)][(int)(yl + y)] = RCC;
    }

    // DRAW THE SELECTED RADIAL LINE IN THE APPROPRIATE COLOUR
    for(i = 0 ; i < wp.R ; i++) {
      x = i * Math.sin(OSR); y = i * Math.cos(OSR); 
      C[(int)(x + wp.X)][(int)(y + wp.Y)] = SRC;
    }
    int I = (int)wp.X, J = (int)wp.Y;   // DRAW IN THE WAYPOINT ITSELF
    for(i = I - 2 ; i < I + 3 ; i++)    // Draw the waypoint as a
      for(j = J - 2 ; j < J + 3 ; j++)  // small white square...
        C[i][j] = ATC;
    C[I - 2][J - 2] = BGC;  //  ...rounded off at corners to
    C[I + 2][J + 2] = BGC;  // make it into  a circular blob.
    C[I - 2][J + 2] = BGC;
    C[I + 2][J - 2] = BGC;

    // DRAW THE LITTLE NORTH ARROW
    I = 30;
    J = 150;
    for(i = -10 ; i < 11 ; i++)
      C[I + i][J] = Color.white;
    for(j = -20 ; j < 21 ; j++)
      C[I][J + j] = Color.white;
    for(i = -3 ; i < 0 ; i++) {
      C[I + i][J + 20 + i] = Color.white;
      C[I - i][J + 20 + i] = Color.white;
    }
    for(j = -2 ; j < 3 ; j++)
      C[I - 2][J + 25 + j] = Color.white;
    for(j = -2 ; j < 3 ; j++)
      C[I + 2][J + 25 + j] = Color.white;
    for(j = -1 ; j < 2 ; j++)
      C[I - j][J + 25 + j] = Color.white;
  }


  void PlotPosn(aircraft ac) {      // PLOT THE AIRCRAFT'S CURRENT POSITION
    C[(int)ac.x][(int)ac.y] = ATC;  // plot its position on the
  }                                 // tracking display raster
}