我有一个使用 SurfaceView 的小游戏。我的“船”只是一个白色的矩形，障碍物是小行星的位图。当一颗小行星与飞船相撞时，应该会出现一个爆炸动画，其中有 20 block fragment (只是一个 10 x 10 的白点)向四面八方飞出。
问题是当碰撞发生时，所有的 fragment 都只是在一个地方旋转一圈，如下所示:
爆炸确实是从我船的确切位置开始的。粒子只是不向外移动。我把代码放错地方了吗？有谁知道我哪里出了问题？
这是类:
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import java.util.Random;
public class GameView extends SurfaceView implements Runnable, SurfaceHolder.Callback {
private Thread gameViewThread = null;
SurfaceHolder surfaceHolder;
boolean okToRun;
/*
SHIP AND ASTEROID STUFF
*/
private Ship ship;
private Point shipPoint;
private Rect textRect = new Rect();
private float oldX;
private float oldY;
private AsteroidController asteroidController;
/*
END SHIP AND ASTEROID STUFF
*/
/*
GAME OVER STUFF
*/
private boolean isMoving = false;
private boolean isGameOver = false;
private long waitTime;
/*
END GAME OVER STUFF
*/
/*
EXPLOSION STUFF
*/
Bitmap explosionBMP;
private Matrix[] explosion = new Matrix[20];
boolean isDestroyed = false;
boolean explosionStarted = false;
float[] explosionXPosition = new float[20];
float[] explosionYPosition = new float[20];
float explosionSpeed = 20.0f;
float[] explosionRotation = new float[20];
/*
END EXPLOSION STUFF
*/
/*
SCREEN DIMENSIONS
*/
DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
int gameWidth = displayMetrics.widthPixels;
int gameHeight = displayMetrics.heightPixels;
/*
END SCREEN DIMENSIONS
*/
public GameView(Context context) {
super(context);
surfaceHolder = this.getHolder();
okToRun = true;
ship = new Ship(new Rect(100, 100, 200, 200), Color.WHITE);
shipPoint = new Point(gameWidth / 2, 3 * gameHeight / 4);
ship.update(shipPoint);
asteroidController = new AsteroidController(context);
//JUST SPAWNING ONE ASTEROID FOR NOW
asteroidController.createAsteroid(1);
//JUST A 10 x 10 WHITE DOT
explosionBMP = BitmapFactory.decodeResource(getResources(), R.drawable.explosion_debris);
//DON'T WANT A NULL POINTER RIGHT OFF THE BAT
for(int i = 0; i < explosion.length; i++) {
explosion[i] = new Matrix();
}
setFocusable(true);
}
@Override
public void run() {
while(okToRun) {
if(!surfaceHolder.getSurface().isValid()) {
continue;
}
Canvas gameCanvas = surfaceHolder.lockCanvas();
this.update();
this.draw(gameCanvas);
surfaceHolder.unlockCanvasAndPost(gameCanvas);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
isMoving = true;
oldX = event.getX();
oldY = event.getY();
if (isGameOver && System.currentTimeMillis() - waitTime >= 3000) {
isGameOver = false;
resetGame();
}
break;
case MotionEvent.ACTION_MOVE:
if (!isGameOver && isMoving) {
/*
THIS CODE ALLOWS TOUCH EVENT TO BE ANYWHERE ON SCREEN WHILE
SHIP MOVES ACCORDINGLY
*/
float newX = event.getX();
float newY = event.getY();
float deltaX = getOffsetCoords(oldX, newX, shipPoint.x);
float deltaY = getOffsetCoords(oldY, newY, shipPoint.y);
shipPoint.set((int) deltaX, (int) deltaY);
oldX = newX;
oldY = newY;
}
return false;
}
return true;
}
/*
GET THE DIFFERENCE IN SHIP COORDS AND TOUCH COORDS
*/
private float getOffsetCoords(float oldVal, float newVal, float current) {
return current + (newVal - oldVal);
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
//RANDOMS FOR STARS
Random random0 = new Random();
Random random1 = new Random();
//BACKGROUND
canvas.drawColor(Color.BLACK);
Bitmap single_pixel_star = BitmapFactory.decodeResource(getResources(), R.drawable.single_pixel_star);
Bitmap three_pixel_star = BitmapFactory.decodeResource(getResources(), R.drawable.three_pixel_star);
//Draw random stars on the canvas
canvas.drawBitmap(single_pixel_star, random0.nextInt(canvas.getWidth() - single_pixel_star.getWidth()), random0.nextInt(canvas.getHeight() - three_pixel_star.getHeight()), null);
canvas.drawBitmap(three_pixel_star, random1.nextInt(canvas.getWidth() - three_pixel_star.getWidth()), random1.nextInt(canvas.getHeight() - three_pixel_star.getHeight()), null);
//DRAW ASTEROID(s)
asteroidController.render(canvas);
//DRAW SHIP
ship.draw(canvas);
if (isGameOver) {
ship.removeShip();
isDestroyed = true;
explosionStarted = true;
Paint gameOverPaint = new Paint();
gameOverPaint.setTextSize(200);
gameOverPaint.setColor(Color.RED);
showGameOver(canvas, gameOverPaint, "YOU LOSE!");
/*
SHIP GOES KABOOM!
*/
for(int i = 0; i < explosion.length; i++) {
canvas.drawBitmap(explosionBMP, explosion[i], null);
}
}
}
public void update() {
if (!isGameOver) {
ship.update(shipPoint);
asteroidController.update();
if (asteroidController.isCollision(ship)) {
isGameOver = true;
waitTime = System.currentTimeMillis();
}
}
Matrix[] localExplosionDebris = new Matrix[20];
if(explosionStarted) {
for(int i = 0; i < explosionXPosition.length; i++) {
explosionXPosition[i] = getShipPointX();
explosionYPosition[i] = getShipPointY();
Random rand = new Random();
explosionRotation[i] = (float) rand.nextInt(360);
}
explosionStarted = false;
}
for(int i = 0; i < localExplosionDebris.length; i++) {
localExplosionDebris[i] = new Matrix();
}
if(isDestroyed) {
for(int i = 0; i < localExplosionDebris.length; i++) {
float debrisXSpeed = (float) Math.sin(explosionRotation[i]*(Math.PI/180)) * explosionSpeed - .2f;
float debrisYSpeed = (float) Math.cos(explosionRotation[i]*(Math.PI/180)) * explosionSpeed - .2f;
explosionXPosition[i] += debrisXSpeed;
explosionYPosition[i] -= debrisYSpeed;
localExplosionDebris[i].postRotate(0, explosionBMP.getWidth()/2, explosionBMP.getHeight()/2);
localExplosionDebris[i].postTranslate(explosionXPosition[i], explosionYPosition[i]);
explosion[i].set(localExplosionDebris[i]);
}
}
}
/*
SHOW GAME OVER TEXT ON THE CENTER OF THE SCREEN UNTIL 3 SECONDS HAVE PASSED AND TOUCH EVENT OCCURS
*/
private void showGameOver(Canvas canvas, Paint paint, String gameOverString) {
paint.setTextAlign(Paint.Align.LEFT);
canvas.getClipBounds(textRect);
int canvasH = textRect.height();
int canvasW = textRect.width();
paint.getTextBounds(gameOverString, 0, gameOverString.length(), textRect);
float textX = canvasW / 2f - textRect.width() / 2f - textRect.left;
float textY = canvasH / 2f - textRect.height() / 2f - textRect.bottom;
canvas.drawText(gameOverString, textX, textY, paint);
}
/*
RESET SHIP TO ORIGINAL LOCATION AND COLOR
*/
public void resetGame() {
ship = new Ship(new Rect(100, 100, 200, 200), Color.WHITE);
shipPoint = new Point(gameWidth / 2, 3 * gameHeight / 4);
//TODO STOP BG MUSIC ONCE FILE IS ADDED
//TODO RESET SCORE ONCE ADDED
}
public void pause() {
okToRun = false;
while(true) {
try {
gameViewThread.join();
} catch(InterruptedException e) {
Log.d("ERROR", e.getMessage());
}
break;
}
gameViewThread = null;
}
public void resume() {
okToRun = true;
gameViewThread = new Thread(this);
gameViewThread.start();
}
/*
SELF EXPLANATORY
*/
public int getShipPointX() {
return shipPoint.x;
}
public int getShipPointY() {
return shipPoint.y;
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
最佳答案
我重新排列了一些 bool 变量，现在爆炸了。在下面的 if 语句中，你可以看到我注释掉的内容:
if (isGameOver) {
ship.removeShip();
//isDestroyed = true;
//explosionStarted = true;
Paint gameOverPaint = new Paint();
gameOverPaint.setTextSize(200);
gameOverPaint.setColor(Color.RED);
showGameOver(canvas, gameOverPaint, "YOU LOSE!");
/*
SHIP GOES KABOOM!
*/
for(int i = 0; i < explosion.length; i++) {
canvas.drawBitmap(explosionBMP, explosion[i], null);
}
}
在另一个 if 语句中，我添加了一个条件，将注释掉的 bool 值(如上所示)放入该语句，然后在 else 中重置它们:
if (!isGameOver) {
ship.update(shipPoint);
asteroidController.update();
if (asteroidController.isCollision(ship) && !isDestroyed) { //<--added the && !isDestroyed
isGameOver = true;
isDestroyed = true; //<-- added this
explosionStarted = true; //<-- and this
waitTime = System.currentTimeMillis();
} else {
isGameOver = false; //<-- then reset here
isDestroyed = false; //<-- and here
explosionStarted = false; //<-- and here
}
}
全部完成。 :-)
关于android - 位图爆炸动画在一个地方旋转，不向外移动，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47325365/