RobocodeTrigTutorial

I'll give it a quick go. This is assumes you know normal trig before reading. Beware... ;)

The main difference between Robocode trig and normal is where 0 degrees is and the direction of the unit circle.

In normal trig, 0 degrees is at the right edge of the circle and you then traverse counter-clockwise around the unit circle to increase the angle. Robocode places 0 degrees at the top of the circle and you traverse clockwise to increase the angle. Basically, to convert from Polar to Rect (Cartesian) in robocode, you do the following:

X = Math.sin(Angle) * Magnitude of Vector

Y = Math.cos(Angle) * Magnitude of Vector

The Sin / Cos are backwards from normal trig where the Y value would use Sin() and X would use Cos().

Other useful info: To convert from Rect To Polar

Angle = Math.atan2(X, Y);

Magnitude = Point2D.Double.Distance(X, Y, 0, 0);

Note: Point2D is located in java.awt.geom. Also, all trig functions assume Radians, not degrees which is why almost all bots use radians as their default value. Other people: feel free to add more, correct, or place some more info anywhere you want! -- Miked0801

If you want to use degrees, you may find it helpful to define the following methods:

public static double sin(double angle) { return Math.sin(Math.toRadians(angle)); }
public static double cos(double angle) { return Math.cos(Math.toRadians(angle)); }
public static double atan2(double x, double y) { return Math.toDegrees(Math.atan2(x, y)); }

-- Jomel

Can someone explain more about point2D ?? --X-KAM-X

The best way to learn about Point2D is to read the Java API maybe. Anyway Point2D is an interface specifying a number of useful function regarding 2D points. The most often used (in Robocode) instanciating class is Point2D.Double. Search the pages about Gouldingi/Code and GoToBot/Code for "Point2D" and you should see some uses. -- PEZ

OK! I got it. Thanks PEZ ! --X-KAM-X

Err, dont angles work counter clockwise in robocode too? was this a change from the original.