看了李明华老师那本游戏入门， 碰撞检测哪个部分不知道为什么判断时候要多加上那几句，感觉不加上也是可以的呀？？？？ 求指点
现在把demo发上来：
MainActivity.java
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MySurfaceView(this));
}
}
MySurfaceView.java
public class MySurfaceView extends SurfaceView implements Runnable, Callback {
private Canvas canvas;
private Paint paint;
private boolean state;
private boolean isCollision;
private SurfaceHolder holder;
private Thread mThread;
private static final int MAX_TIME = 50;
private int x1 =100,y1 =110,x2 = 100,y2 = 110;
private int h1 = 40,w1 = 40,h2 = 40,w2 = 40;
public MySurfaceView(Context context) {
super(context);
// TODO Auto-generated constructor stub
holder = this.getHolder();
holder.addCallback(this);
paint = new Paint();
paint.setColor(Color.BLUE);
setFocusable(true);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
state = true;
mThread = new Thread(this);
mThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
/* (non-Javadoc)
* @see android.view.View#onTouchEvent(android.view.MotionEvent)
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
x1 = (int)event.getX() - w1/2;
y1 = (int)event.getY() - h1/2;
if (isCollisionWithRect(x1,y1,w1,h1,x2,y2,w2,h2)) {
isCollision = true;
}else {
isCollision = false;
}
return true;
}
private boolean isCollisionWithRect(int x12, int y12, int w12, int h12,
int x22, int y22, int w22, int h22) {
// TODO Auto-generated method stub
if (x1 + w1 <= x2) {
return false;
}else if (x1>=x2 + w2){
return false;
}else if (y1>=y2+h2) {
return false;
}else if (y1+h1<=y2) {
return false;
}
return true;
}
public void mDraw(){
try {
canvas = holder.lockCanvas();
if (canvas != null) {
canvas.drawRGB(0, 0, 0);
if (isCollision) {
paint.setColor(Color.RED);
paint.setTextSize(20);
canvas.drawText("Collision!", 0, 50, paint);
}else {
paint.setColor(Color.WHITE);
}
canvas.drawRect(x1, y1, x1+w1, y1+h1, paint);
canvas.drawRect(x2, y2, x2+w2, y2+h2, paint);
}
} catch (Exception e) {
// TODO: handle exception
}finally{
if (canvas!=null) {
holder.unlockCanvasAndPost(canvas);
}
}
}
private void logic() {
// TODO Auto-generated method stub
}
@Override
public void run() {
// TODO Auto-generated method stub
while (state) {
long start = System.currentTimeMillis();
mDraw();
logic();
long end = System.currentTimeMillis();
try {
if ((end - start) < MAX_TIME) {
Thread.sleep(MAX_TIME - (end - start));
}
} catch (Exception e) {
// TODO: handle exception
}
}
}
}
运行效果：
未发生碰撞，
发生碰撞：
其中，在检测碰撞的代码部分，书本上面是这样子的（意思就是排除两个矩形不碰撞的情形，剩余的情况即发生了碰撞）：
但是我觉得只要这样写不就行了吗：？？？？
private boolean isCollisionWithRect(int x12, int y12, int w12, int h12,
int x22, int y22, int w22, int h22) {
// TODO Auto-generated method stub
if (x1 + w1 <= x2) {
return false;
}else if (x1>=x2 + w2){
return false;
}else if (y1>=y2+h2) {
return false;
}else if (y1+h1<=y2) {
return false;
}
return true;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
圆形区域的碰撞检测：
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new CircleCollisionDemo(this));
}
}
public class CircleCollisionDemo extends SurfaceView implements Runnable, Callback{
private Canvas canvas;
private Paint paint;
private boolean state;
private boolean isCollision;
private SurfaceHolder holder;
private Thread mThread;
private static final int MAX_TIME = 50;
private int x1 =100,y1 =110,x2 = 100,y2 = 110;
private int r1 = 40,r2 = 50;
public CircleCollisionDemo(Context context) {
super(context);
// TODO Auto-generated constructor stub
holder = this.getHolder();
holder.addCallback(this);
paint = new Paint();
paint.setColor(Color.BLUE);
setFocusable(true);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
state = true;
mThread = new Thread(this);
mThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
/* (non-Javadoc)
* @see android.view.View#onTouchEvent(android.view.MotionEvent)
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
x1 = (int)event.getX();
y1 = (int)event.getY();
if (isCollisionWithCircle(x1,y1,x2,y2,r1,r2)) {
isCollision = true;
}else {
isCollision = false;
}
return true;
}
private boolean isCollisionWithCircle(int x12, int y12, int x22, int y22, int r11, int r22) {
// TODO Auto-generated method stub
if (Math.sqrt(Math.pow(x12-x22, 2) + Math.pow(y12-y22, 2)) <= r1+r2) {
return true;
}else {
return false;
}
//return false;
}
public void mDraw(){
try {
canvas = holder.lockCanvas();
if (canvas != null) {
canvas.drawRGB(0, 0, 0);
if (isCollision) {
paint.setColor(Color.RED);
paint.setTextSize(20);
canvas.drawText("Collision!", 0, 50, paint);
}else {
paint.setColor(Color.WHITE);
}
canvas.drawCircle(x1, y1, r1, paint);
canvas.drawCircle(x2, y2, r2, paint);
}
} catch (Exception e) {
// TODO: handle exception
}finally{
if (canvas!=null) {
holder.unlockCanvasAndPost(canvas);
}
}
}
private void logic() {
// TODO Auto-generated method stub
}
@Override
public void run() {
// TODO Auto-generated method stub
while (state) {
long start = System.currentTimeMillis();
mDraw();
logic();
long end = System.currentTimeMillis();
try {
if ((end - start) < MAX_TIME) {
Thread.sleep(MAX_TIME - (end - start));
}
} catch (Exception e) {
// TODO: handle exception
}
}
}
}
运行效果：
时间： 2024-09-29 20:07:36