Compass Reader Basic by 祥瑞

利用compass sensor, 在螢幕顯示亙指北方的箭頭

import lejos.nxt.*;
import lejos.nxt.addon.CompassSensor;
import lejos.util.Delay;
import javax.microedition.lcdui.Graphics;

class Compass {
    public static CompassSensor compass = new CompassSensor(SensorPort.S1);
    public static int lineLength = 50; //線長度
    public static int arrowLength = 15; //箭頭線長度
    public static int arrowAng = 30; //箭頭線與線的角度
    public static int dots = 12; //圓周點的數目
    public static int delay = 150; //更新螢幕間隔
    
    public static int offsetX;
    public static int offsetY;
    public static Graphics g = new Graphics();
    public static double direction;
    public static void main(String args[]) {
        Button.ESCAPE.addButtonListener(new ButtonListener()
        {
            public void buttonPressed(Button b){System.exit(0);}
            public void buttonReleased(Button b){}
        });
        while(true) {
            direction = compass.getDegreesCartesian();
            g.drawLine(getLocationX(direction, lineLength), getLocationY(direction, lineLength), 100-getLocationX(direction, lineLength), 64-getLocationY(direction, lineLength));
            g.drawLine(getLocationX(direction, lineLength), getLocationY(direction, lineLength), getLocationX(direction, lineLength) + (int)(Math.cos(Math.toRadians(direction+90-arrowAng))*arrowLength), getLocationY(direction, lineLength) + (int)(Math.sin(Math.toRadians(direction+90-arrowAng))*arrowLength));
            g.drawLine(getLocationX(direction, lineLength), getLocationY(direction, lineLength), getLocationX(direction, lineLength) – (int)(Math.cos(Math.toRadians(90-direction-arrowAng))*arrowLength), getLocationY(direction, lineLength) + (int)(Math.sin(Math.toRadians(90-direction-arrowAng))*arrowLength));
            g.drawString("N", getLocationX(direction, lineLength+10)-LCD.FONT_WIDTH/2 , getLocationY(direction, lineLength+10)-LCD.FONT_HEIGHT/2);
            g.drawString("W", getLocationX(direction+270, lineLength+10)-LCD.FONT_WIDTH/2 , getLocationY(direction+270, lineLength+10)-LCD.FONT_HEIGHT/2);
            g.drawString("E", getLocationX(direction+90, lineLength+10)-LCD.FONT_WIDTH/2 , getLocationY(direction+90, lineLength+10)-LCD.FONT_HEIGHT/2);
            g.drawString("S", getLocationX(direction+180, lineLength+10)-LCD.FONT_WIDTH/2 , getLocationY(direction+180, lineLength+10)-LCD.FONT_HEIGHT/2);
            for(int i=0; i<360; i+=360/dots) g.drawLine(getLocationX(direction+i, lineLength), getLocationY(direction+i, lineLength), getLocationX(direction+i, lineLength-5), getLocationY(direction+i, lineLength-5));
            Delay.msDelay(delay);
            LCD.clear();
        }
    }
    
    public static int getLocationX(double ang, int length) {
        return 50 + (int)(Math.sin(Math.toRadians(ang))*length/2);
    }
    public static int getLocationY(double ang, int length) {
        return 32 – (int)(Math.cos(Math.toRadians(ang))*length/2);
    }
}