npcsprite.java

一个飞机类游戏

package enemy;

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;

public class NPCSprite extends Sprite {
	public static final int NPC_CANON1 = 1;

	public static final int NPC_CANON2 = 2;

	public static final int NPC_CANON3 = 3;

	public static final int NPC_FLYER1 = 4;

	public static final int NPC_FLYER2 = 5;

	public static final int NPC_FLYER3 = 6;

	public static final int NPC_FLYER4 = 7;

	public static final int NPC_TANK1 = 8;

	public static final int NPC_TANK2 = 9;

	int npcType;

	int scnWidth, scnHeight;

	private int mDirection;

	private int mKX, mKY;

	private int mLastDelta;

	private boolean mLastWasTurn;

	static final int SPC = 6;

	boolean firing;

	int firingDelay = 500;

	long timeLastFired;

	int frameOffset;

	private static final int[] kTransformLookup = { Sprite.TRANS_NONE,
			Sprite.TRANS_NONE, Sprite.TRANS_NONE, Sprite.TRANS_MIRROR_ROT90,
			Sprite.TRANS_ROT90, Sprite.TRANS_ROT90, Sprite.TRANS_ROT90,
			Sprite.TRANS_MIRROR_ROT180, Sprite.TRANS_ROT180,
			Sprite.TRANS_ROT180, Sprite.TRANS_ROT180,
			Sprite.TRANS_MIRROR_ROT270, Sprite.TRANS_ROT270,
			Sprite.TRANS_ROT270, Sprite.TRANS_ROT270, Sprite.TRANS_MIRROR };

	private static final int[] kFrameLookup = { 0, 1, 2, 1, 0, 1, 2, 1, 0, 1,
			2, 1, 0, 1, 2, 1 };

	private static final int[] kCosLookup = { 0, 383, 707, 924, 1000, 924, 707,
			383, 0, -383, -707, -924, -1000, -924, -707, -383 };

	private static final int[] kSinLookup = { 1000, 924, 707, 383, 0, -383,
			-707, -924, -1000, -924, -707, -383, 0, 383, 707, 924 };

	public NPCSprite(Image image, int frameWidth, int frameHeight, int npcType,
			int scnWidth, int scnHeight) {
		super(image, frameWidth, frameHeight);
		defineReferencePixel(frameWidth / 2, frameHeight / 2);
		mDirection = 0;
		this.npcType = npcType;
		this.scnWidth = scnWidth;
		this.scnHeight = scnHeight;

		// Hack 1:1 relation to the PNG file 3 frames of cannons first then a
		// flyer... as we add more NPCs
		// this switch needs to be updated accordingly
		switch (npcType) {
		case NPC_CANON1:
			this.frameOffset = 0;
			this.setFrame(0);
			break;
		case NPC_CANON2:
			this.frameOffset = 3;
			this.setFrame(3);
			break;
		case NPC_CANON3:
			this.frameOffset = 6;
			this.setFrame(6);
			break;
		case NPC_FLYER1:
			this.frameOffset = 9;
			this.setFrame(9);
			break;
		case NPC_FLYER2:
			this.frameOffset = 12;
			this.setFrame(12);
			break;
		case NPC_FLYER3:
			this.frameOffset = 15;
			this.setFrame(15);
			break;
		case NPC_FLYER4:
			this.frameOffset = 18;
			this.setFrame(18);
			break;
		case NPC_TANK1:
			this.frameOffset = 21;
			this.setFrame(21);
			break;
		case NPC_TANK2:
			this.frameOffset = 24;
			this.setFrame(24);
			break;
		}
	}

	public int getMidX() {
		return getX() + (getHeight() / 2);
	}

	public int getMidY() {
		return getY() + (getWidth() / 2);
	}

	public void turn(int delta) {
		mDirection += delta;
		if (mDirection < 0)
			mDirection += 16;
		if (mDirection > 15)
			mDirection %= 16;

		setFrame(kFrameLookup[mDirection] + frameOffset);
		setTransform(kTransformLookup[mDirection]);

		mLastDelta = delta;
		mLastWasTurn = true;
	}

	public void forward(int delta) {
		fineMove(kCosLookup[mDirection] * delta, -kSinLookup[mDirection]
				* delta);
		mLastDelta = delta;
		mLastWasTurn = false;
	}

	public void undo() {
		if (mLastWasTurn)
			turn(-mLastDelta);
		else
			forward(-mLastDelta);
	}

	private void fineMove(int kx, int ky) {
		int x = getX();
		int y = getY();

		int errorX = Math.abs(mKX - x * 1000);
		int errorY = Math.abs(mKY - y * 1000);
		if (errorX > 1000 || errorY > 1000) {
			mKX = x * 1000;
			mKY = y * 1000;
		}
		// Now add the deltas.
		mKX += kx;
		mKY += ky;

		// Set the actual position.
		setPosition(mKX / 1000, mKY / 1000);
	}

	public Bullet fire(PlayerSprite player, Image bullets) throws Exception {
		Bullet bullet = null;
		if (getY() > 0 && getY() < scnHeight && !collidesWith(player, false)) {
			int pDir = getPlayerDirection(player);

			if (pDir == mDirection) {
				long timeSinceLastFire = (System.currentTimeMillis() - timeLastFired);
				if (!firing && timeSinceLastFire > firingDelay) {
					bullet = new Bullet(bullets, 2, 2, Bullet.TYPE_NPC1_DAMAGE);
					bullet.setPosition(getMidX(), getMidY());
					bullet.setDirection(mDirection);
					timeLastFired = System.currentTimeMillis();
				} else {
					firing = false;
				}
			} else if (pDir > mDirection) {
				//pDir比mDirection超出太多，反转更合算
				if (pDir - mDirection > 8)
					turn(-1);
				else
					turn(1);
			} else if (pDir < mDirection) {
				if (mDirection - pDir < 8)
					turn(-1);
				else
					turn(1);
			}
		}
		return bullet;
	}

	// Major hack and magic numbers here, sorry I'll try and make this more
	// readable later
	private int getPlayerDirection(PlayerSprite player) {

		// Beside the NPC
		if (player.getMidY() <= (getMidY() + SPC)
				&& player.getMidY() >= (getMidY() - SPC)) {
			if (player.getX() < getX())
				return 12;
			else
				return 4;
		} else if (player.getMidX() >= getMidX() - SPC
				&& player.getMidX() <= getMidX() + SPC) {
			if (player.getY() > getY())
				return 8;
			else
				return 0;

			// Quad 4
		} else if (player.getMidX() <= getMidX()
				&& player.getMidY() <= getMidY()) {

			int qC = quadCalc(player);
			if (qC <= SPC)
				return 14;
			else if (Math.abs(player.getMidX() - getMidX()) > Math.abs(player
					.getMidY()
					- getMidY()))
				return 13;
			else
				return 15;

			// Quad 3
		} else if (player.getMidX() <= getMidX()
				&& player.getMidY() >= getMidY()) {
			int qC = quadCalc(player);
			if (qC <= SPC)
				return 10;
			else if (Math.abs(player.getMidX() - getMidX()) > Math.abs(player
					.getY()
					- getMidY()))
				return 11;
			else
				return 9;

			// Quad 2
		} else if (player.getMidX() >= getMidX()
				&& player.getMidY() >= getMidY()) {
			int qC = quadCalc(player);
			if (qC <= SPC)
				return 6;
			else if (Math.abs(player.getMidX() - getMidX()) > Math.abs(player
					.getY()
					- getMidY()))
				return 5;
			else
				return 7;

			// Quad 1
		} else if (player.getMidX() >= getMidX()
				&& player.getMidY() <= getMidY()) {
			int qC = quadCalc(player);
			if (qC <= 5)
				return 2;
			else if (Math.abs(player.getMidX() - getMidX()) > Math.abs(player
					.getY()
					- getMidY()))
				return 3;
			else
				return 1;
		}

		// Should never reach here
		return -1;
	}
	
	//x 坐标的差和y坐标的差  的差

	private int quadCalc(PlayerSprite player) {
		return Math.abs((Math.abs(player.getMidX() - getMidX()))
				- (Math.abs(player.getMidY() - getMidY())));
	}

}