Computer Science 120
Introduction to Programming

Spring 2012, Siena College

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Railroad Demo

A working demo of Railroad will appear below. Click inside the applet to interact with it.

Railroad BlueJ Project

Click here to download a BlueJ project for Railroad.

Railroad Source Code

The Java source code for Railroad is below. Click on a file name to download it.

Railroad.java

import objectdraw.*;
import java.awt.*;

/*
 * Example Railroad -- draw a railroad track with a loop
 *
 * Jim Teresco, Siena College, CSIS 120, Spring 2011, Spring 2012
 *
 * $Id: Railroad.java 1535 2011-02-14 03:49:40Z terescoj $
 */

public class Railroad extends WindowController {

    // screen dimensions
    private static final int SCREEN_HEIGHT = 400;
    private static final int SCREEN_WIDTH = 400;

    // distance between rails
    private static final double GAUGE = 100;
    // where to start top rail
    private static final double TRACK_TOP = (SCREEN_HEIGHT - GAUGE) / 2;
    // width of rail
    private static final double RAIL_WIDTH = 10;
    // width of tie
    private static final double TIE_WIDTH = 20;
    // how far tie extends beyond rails
    private static final double TIE_EXTEND = 20;
    // length of tie
    private static final double TIE_LENGTH = GAUGE + 2 * RAIL_WIDTH + 2 * TIE_EXTEND;
    // distance between successive ties
    private static final double TIE_SPACING = 25;
    // coordinate of top of ties
    private static final double TIE_TOP = TRACK_TOP - TIE_EXTEND;
    // x coordinate of first tie
    private static final double FIRST_TIE_X = 5;

    // colors of ground, rails, and ties
    private final Color GROUND_COLOR = new Color(50, 150, 50);
    private final Color RAIL_COLOR = new Color(200, 200, 200);
    private final Color TIE_COLOR = new Color(150, 40, 40);

    // rails of track
    private FilledRect rail1, rail2;

    public void begin() {

        // draw rails and background
        new FilledRect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, canvas).setColor(GROUND_COLOR);
        rail1 = new FilledRect(0, TRACK_TOP, SCREEN_WIDTH, RAIL_WIDTH, canvas);
        rail1.setColor(RAIL_COLOR);
        rail2 = new FilledRect(0, TRACK_TOP + GAUGE, SCREEN_WIDTH, RAIL_WIDTH, canvas);
        rail2.setColor(RAIL_COLOR);

        // the first tie will be drawn here
        double tiePosition = FIRST_TIE_X;

        // draw each successive tie as long as it will be on the canvas
        while ( tiePosition < SCREEN_WIDTH ) {
            new FilledRect(tiePosition, TIE_TOP, TIE_WIDTH, TIE_LENGTH,
                canvas).setColor(TIE_COLOR);  
            // move rails on top of new tie
            rail1.sendToFront();            
            rail2.sendToFront();
            
            // update position for next tie
            tiePosition = tiePosition + TIE_WIDTH + TIE_SPACING;
        }
    }
}