User:Chase-san/MovSim

This is the move simulator I created, for use in Precise Prediction, it was influenced by Albert's Precise Prediction code. Unlike his it doesn't handle distance, but that is a very complicated set of code (which I might add later if there is a need).

This and all my other code in which I display on the robowiki falls under the ZLIB License.

import robocode.Rules;
import robocode.util.Utils;

public final class Simulator {
	public static final boolean useNewDeaccelRule = true;
	
	public Point2D.Double position;
	public double heading;
	public double velocity;
	public double headingDelta;
	public double maxVelocity;
	public double angleToTurn;
	public int direction;
	
	public Simulator() {
		position = new Point2D.Double();
		maxVelocity = Rules.MAX_VELOCITY;
		direction = 1;
	}

	public void setPos(double x, double y) {
		position.x = x;
		position.y = y;
	}

	public void step() {
		////////////////
		//Heading
		double lastHeading = heading;
		double turnRate = Rules.getTurnRateRadians(Math.abs(velocity));
		double turn = Math.min(turnRate, Math.max(angleToTurn, -turnRate));
		heading = Utils.normalNearAbsoluteAngle(heading + turn);
		angleToTurn -= turn;
		
		////////////////
		//Movement
		if(direction != 0 || velocity != 0.0) {
			////////////////
			//Acceleration
			double acceleration = 0;
			double absVelocity = Math.abs(velocity);
			maxVelocity = Math.abs(maxVelocity);
			
			//Stop and ask for directions
			int velDirection = (velocity > 0 ? (int)1 : (int)-1);
			
			//Handles direction zero stop
			if(direction == 0) {
				maxVelocity = 0;
				direction = velDirection;
			}
			
			//Handles speedup from zero
			if(absVelocity < 0.000001) {
				velDirection = direction;
			}
			
			//Check directions
			if(velDirection == direction) {
				if(absVelocity <= maxVelocity) {
					//We are speeding up
					acceleration = Math.min(Rules.ACCELERATION, maxVelocity - absVelocity);
				} else {
					//We are slowing down in the same direction
					if(absVelocity > maxVelocity)
						acceleration = Math.max(-Rules.DECELERATION, maxVelocity - absVelocity);
				}
			} else {
				//If this is the case then we are always slowing down
				if(absVelocity < Rules.DECELERATION) {
					//Do we pass over zero, special rules are here for this
					double beyondZero = Math.abs(absVelocity - Rules.DECELERATION);
					if(useNewDeaccelRule) {
						acceleration = absVelocity + (beyondZero /= 2.0);
					} else {
						acceleration = Rules.DECELERATION;
					}
					//Limit our acceleration so it does not go beyond max when passing over zero
					if(beyondZero > maxVelocity)
						acceleration = absVelocity + maxVelocity;
				} else {
					//Otherwise
					acceleration = Rules.DECELERATION;
				}
			}
			
			acceleration *= direction;
			
			////////////////
			//Velocity
			velocity = Math.min(Math.max(-Rules.MAX_VELOCITY, velocity + acceleration), Rules.MAX_VELOCITY);
			
			////////////////
			//Position
			position.x += Math.sin(heading) * velocity;
			position.y += Math.cos(heading) * velocity;
		}
		
		headingDelta = Utils.normalRelativeAngle(heading - lastHeading);
	}
}