Battlecode 2021 Pathfinding lecture

RobotPlayer.java

/*
 * Battlecode 2021
 * Pathfinding Lecture - sample code
 *
 * Bug pathing and communication strategies. Run this on the map "Quadrants" for a sense of how
 * this strategy behaves: watch the red robots in the bottom-left corner.
 *
 * https://www.battlecode.org/
 * https://github.com/battlecode/battlecode21
 */

package examplefuncsplayer;

import battlecode.common.*;

public strictfp class RobotPlayer {
    static RobotController rc;

    /**
     * run() is the method that is called when a robot is instantiated in the Battlecode world.
     * If this method returns, the robot dies!
     **/
    @SuppressWarnings("unused")
    public static void run(RobotController rc) throws GameActionException {

        // This is the RobotController object. You use it to perform actions from this robot,
        // and to get information on its current status.
        RobotPlayer.rc = rc;
        System.out.println("I'm a " + rc.getType() + " and I just got created!");

        while (true) {
            // Try/catch blocks stop unhandled exceptions, which cause your robot to freeze
            try {
                // Here, we've separated the controls into a different method for each RobotType.
                // You may rewrite this into your own control structure if you wish.
                switch (rc.getType()) {
                    case ENLIGHTENMENT_CENTER: runEnlightenmentCenter(); break;
                    case POLITICIAN:           runPolitician();          break;
                    default: return;  // we're not creating these here
                }

                // Clock.yield() makes the robot wait until the next turn, then it will perform this loop again
                Clock.yield();

            } catch (Exception e) {
                System.out.println(rc.getType() + " Exception");
                e.printStackTrace();
            }
        }
    }

    /** Enlightenment centers spam politicians */
    static void runEnlightenmentCenter() throws GameActionException {
        RobotType toBuild = RobotType.POLITICIAN;
        int influence = 50;
        for (Direction dir : Direction.values()) {
            if (rc.canBuildRobot(toBuild, dir, influence)) {
                rc.buildRobot(toBuild, dir, influence);
            } else {
                break;
            }
        }
        // a bit silly, but something for the sake of example:
        sendLocation(rc.getLocation().translate(15, 7));
    }

    static int enlightenmentCenterId = -1;
    static MapLocation politicianTarget = null;
    static void runPolitician() throws GameActionException {
        if (enlightenmentCenterId == -1) {
            for (RobotInfo robot : rc.senseNearbyRobots(-1, rc.getTeam())) {
                if (robot.type == RobotType.ENLIGHTENMENT_CENTER) {
                    enlightenmentCenterId = robot.ID;
                }
            }
        }
        if (rc.canGetFlag(enlightenmentCenterId)) {
            politicianTarget = getLocationFromFlag(rc.getFlag(enlightenmentCenterId));
        }
        if (politicianTarget != null) {
            basicBug(politicianTarget);
        }
    }


    ////////////////////////////////////////////////////////////////////////////
    // COMMUNICATION

    static final int NBITS = 7;
    static final int BITMASK = (1 << NBITS) - 1;

    static void sendLocation(MapLocation location) throws GameActionException {
        int x = location.x, y = location.y;
        int encodedLocation = ((x & BITMASK) << NBITS) + (y & BITMASK);
        if (rc.canSetFlag(encodedLocation)) {
            rc.setFlag(encodedLocation);
        }
    }

    @SuppressWarnings("unused")
    static void sendLocation(MapLocation location, int extraInformation) throws GameActionException {
        int x = location.x, y = location.y;
        int encodedLocation = (extraInformation << (2*NBITS)) + ((x & BITMASK) << NBITS) + (y & BITMASK);
        if (rc.canSetFlag(encodedLocation)) {
            rc.setFlag(encodedLocation);
        }
    }

    static MapLocation getLocationFromFlag(int flag) {
        int y = flag & BITMASK;
        int x = (flag >> NBITS) & BITMASK;
        // int extraInformation = flag >> (2*NBITS);

        MapLocation currentLocation = rc.getLocation();
        int offsetX128 = currentLocation.x >> NBITS;
        int offsetY128 = currentLocation.y >> NBITS;
        MapLocation actualLocation = new MapLocation((offsetX128 << NBITS) + x, (offsetY128 << NBITS) + y);

        // You can probably code this in a neater way, but it works
        MapLocation alternative = actualLocation.translate(-(1 << NBITS), 0);
        if (rc.getLocation().distanceSquaredTo(alternative) < rc.getLocation().distanceSquaredTo(actualLocation)) {
            actualLocation = alternative;
        }
        alternative = actualLocation.translate(1 << NBITS, 0);
        if (rc.getLocation().distanceSquaredTo(alternative) < rc.getLocation().distanceSquaredTo(actualLocation)) {
            actualLocation = alternative;
        }
        alternative = actualLocation.translate(0, -(1 << NBITS));
        if (rc.getLocation().distanceSquaredTo(alternative) < rc.getLocation().distanceSquaredTo(actualLocation)) {
            actualLocation = alternative;
        }
        alternative = actualLocation.translate(0, 1 << NBITS);
        if (rc.getLocation().distanceSquaredTo(alternative) < rc.getLocation().distanceSquaredTo(actualLocation)) {
            actualLocation = alternative;
        }
        return actualLocation;
    }


    ////////////////////////////////////////////////////////////////////////////
    // BASIC BUG - just follow the obstacle while it's in the way
    //             not the best bug, but works for "simple" obstacles
    //             for better bugs, think about Bug 2!

    static final double passabilityThreshold = 0.7;
    static Direction bugDirection = null;

    static void basicBug(MapLocation target) throws GameActionException {
        Direction d = rc.getLocation().directionTo(target);
        if (rc.getLocation().equals(target)) {
            // do something else, now that you're there
            // here we'll just explode
            if (rc.canEmpower(1)) {
                rc.empower(1);
            }
        } else if (rc.isReady()) {
            if (rc.canMove(d) && rc.sensePassability(rc.getLocation().add(d)) >= passabilityThreshold) {
                rc.move(d);
                bugDirection = null;
            } else {
                if (bugDirection == null) {
                    bugDirection = d;
                }
                for (int i = 0; i < 8; ++i) {
                    if (rc.canMove(bugDirection) && rc.sensePassability(rc.getLocation().add(bugDirection)) >= passabilityThreshold) {
                        rc.setIndicatorDot(rc.getLocation().add(bugDirection), 0, 255, 255);
                        rc.move(bugDirection);
                        bugDirection = bugDirection.rotateLeft();
                        break;
                    }
                    rc.setIndicatorDot(rc.getLocation().add(bugDirection), 255, 0, 0);
                    bugDirection = bugDirection.rotateRight();
                }
            }
        }
    }
}

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