I want to check collision detection in a game (the code is below). I have a game class in which I am drawing bitmaps, making touch events and make an array list for moving a vehicle. In the vehicle class, I'm taking its getter setter bitmaps and the same in the frog class as vehicle.
I have a frog which is moving in all four directions. The vehicle is moving horizontally. Now if a frog touches a vehicle it should collide with it. What should I do to check collision by measuring height and width?
My code is:
For class Game:
public class Game extends SurfaceView implements SurfaceHolder.Callback {
private Frog frog;
private FrogControl fg;
private FrogControlY fg1;
private MainThread thread;
//private Vehicle vh;
ImageView imgview = (ImageView)findViewById(R.id.imageview);
ImageView imageArr[] = new ImageView[20];
int id[] = {R.drawable.audi_r8, R.drawable.bike, R.drawable.bus, R.drawable.car,
R.drawable.chrysler, R.drawable.cruise_bike};
ArrayList<Vehicle> vh = new ArrayList<Vehicle>();
ArrayList<VehicleReverse> vhs = new ArrayList<VehicleReverse>();
public Game(Context context) {
super(context);
getHolder().addCallback(this);
frog= new Frog(BitmapFactory.decodeResource(getResources(), R.drawable.frog),100,400);
fg= new FrogControl(BitmapFactory.decodeResource(getResources(), R.drawable.arrow),250,400);
fg1=new FrogControlY(BitmapFactory.decodeResource(getResources(), R.drawable.arrow),0,400);
int noOfCar=(int)Math.random()*5;
int totalCar=3+noOfCar;
for(int j=0;j<totalCar; j++){
int y=(int)(Math.random()*3);
int[] LaneSelection = {50,150,250};
int yValue=LaneSelection[y];
int x=0;
vh.add(new Vehicle(BitmapFactory.decodeResource(getResources(), id[y]),x,yValue));
}
for(int k=totalCar-1; k>0; k--){
int y=(int)(Math.random()*3);
int[] LaneSelection = {100,200,300};
int yValue=LaneSelection[y];
int x=300;
vhs.add(new VehicleReverse(BitmapFactory.decodeResource(getResources(), id[y]),x,yValue));
}
thread=new MainThread(getHolder(),this);
setFocusable(true);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Nothing
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
thread.setRunning(true);
thread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry=true;
thread.setRunning(false);
while(retry){
try{
thread.join();
retry=false;
}catch(Exception e){
}
}
}
@Override
public boolean onTouchEvent(MotionEvent event){
if(event.getAction()==MotionEvent.ACTION_DOWN){
// vh.carmove();
fg.handleAction((int)event.getX(), (int)event.getY());
fg1.handleActionY((int)event.getX(), (int)event.getY());
if(fg.isTouched()){
//fg1.setTouchedY(false);
if((int)event.getX()<(250+(fg.getX()/2))&& (frog.getX()>0)){
frog.frogShiftLeft();
// fg1.setTouchedY(true);
}
if((int)event.getX()>=(250+(fg.getX()/2))&&(frog.getX()<300)){
frog.frogShiftRight();
}
}
if(fg1.isTouched()){
//fg.setTouched(false);
if((int)event.getY()<(380+(fg1.getY()/2))&& (frog.getY()>0)&&((int)event.getX()<100)){
frog.frogShiftUp();
// fg.setTouched(true);
}
if((int)event.getY()>=(380+(fg1.getY()/2))&&(frog.getY()<400)&&((int)event.getX()<100)){
frog.frogShiftDown();
}
}
}
if(event.getAction()==MotionEvent.ACTION_MOVE){}
if(event.getAction()==MotionEvent.ACTION_UP){
if(frog.isTouched()){
frog.setTouched(false);
}
}
return true;
}
public void render(Canvas canvas){
canvas.drawColor(Color.BLACK);
fg.draw(canvas);
fg1.draw(canvas);
frog.draw(canvas);
for(int j=0;j<vh.size();j++){
//for(int j=vh.size()-1; j>0; j--){
Vehicle o=vh.get(j);
o.draw(canvas);
}
for(int k=vhs.size()-1; k>0; k--){
VehicleReverse v=vhs.get(k);
v.draw(canvas);
}
}
}
For the Frog class:
import android.graphics.Bitmap;
import android.graphics.Canvas;
public class Frog {
private Bitmap bmp;
private int x;
private int y;
private boolean touched;
public Frog(Bitmap bitmap,int x,int y){
this.bmp=bitmap;
this.x=x;
this.y=y;
}
public Bitmap getBmp() {
return bmp;
}
public void setBmp(Bitmap bmp) {
this.bmp = bmp;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public boolean isTouched(){
return touched;
}
public void setTouched(boolean touched){
this.touched=touched;
}
public void draw(Canvas canvas){
canvas.drawBitmap(bmp, x, y,null);
}
public void frogShiftRight(){
this.x=this.x+20;
}
public void frogShiftLeft(){
this.x=this.x-20;
}
public void frogShiftUp(){
this.y=this.y-20;
}
public void frogShiftDown(){
this.y=this.y+20;
}
}
And for the Vehicle class:
public class Vehicle extends Thread implements Runnable{
private Bitmap bmp;
private static int x;
private int y;
Frog frog;
Vehicle vehicle;
public Vehicle(Bitmap bitmap,int x,int y){
this.bmp=bitmap;
this.x=x;
this.y=y;
}
public Bitmap getBmp() {
return bmp;
}
public void setBmp(Bitmap bmp) {
this.bmp = bmp;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public void carmove(){
try {
x = x + 5;
if(x>=300){
x=-50;
}
} catch (Exception e) {
e.printStackTrace();
}
setX(x);
}
public void collision(){
if(frog.getX() <= x + getX() && frog.getY() <= y + getY()){
Toast.makeText(getApplicationContext(), "Collided", Toast.LENGTH_SHORT).show();
}
}
private Context getApplicationContext() {
// TODO Auto-generated method stub
return null;
}
public void draw(Canvas canvas){
canvas.drawBitmap(bmp, x, y,null);
carmove();
collision();
}
}
See Question&Answers more detail:
os 
