Question

您好我正在尝试制作像斗球一样的游戏，

我在iPhone中使用box2d作为UIView的物理引擎，我创建世界并在其中添加对象。把每件事都设定得很好。

但我不知道当用户释放淀粉时我怎样才能画出淀粉和弹跳。（见图）

请有任何人解决。

Answer 1

我通过以下代码解决了这个问题。声明可变数组。

NSMutableArray *arrTouches;

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    if([[touches allObjects] count] == 1)
    {
        if([arrTouches count]==2)
        {
            UITouch *touch = [[touches allObjects] objectAtIndex:0];
            CGPoint location = [touch locationInView: [touch view]];
            location = [[CCDirector sharedDirector] convertToGL: location];
            [arrTouches replaceObjectAtIndex:1 withObject:NSStringFromCGPoint(location)];
            [self jumpBall];
        }
    }
}

- (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    if([[touches allObjects] count] == 1)
    {
        if([arrTouches count] == 1)
        {
            UITouch *touch = [[touches allObjects] objectAtIndex:0];
            CGPoint location = [touch locationInView: [touch view]];
            location = [[CCDirector sharedDirector] convertToGL: location];
            [arrTouches addObject:NSStringFromCGPoint(location)];
        }
        else if([arrTouches count] == 2)
        {
            UITouch *touch = [[touches allObjects] objectAtIndex:0];
            CGPoint location = [touch locationInView: [touch view]];
            location = [[CCDirector sharedDirector] convertToGL: location];
            [arrTouches replaceObjectAtIndex:1 withObject:NSStringFromCGPoint(location)];
        }
    }
}

- (void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[touches allObjects] objectAtIndex:0];
    CGPoint location = [touch locationInView: [touch view]];
    location = [[CCDirector sharedDirector] convertToGL: location];

    if([[touches allObjects] count] == 1 && CGRectContainsPoint(_ball.boundingBox, location))
    {
        NSLog(@"Touch Begin : X: %f Y: %f",location.x,location.y);
        [arrTouches addObject:NSStringFromCGPoint(location)];
    }
}

-(void)jumpBall
{
    CGPoint diff = ccpSub(CGPointFromString([arrTouches objectAtIndex:0]), CGPointFromString([arrTouches objectAtIndex:1]));

    CGPoint oldP = CGPointFromString([arrTouches objectAtIndex:0]);
    CGPoint newP = CGPointFromString([arrTouches objectAtIndex:1]);

    CGPoint p = CGPointFromString([arrTouches objectAtIndex:1]);

    float floatX = p.x/PTM_RATIO;
    float floatY = p.y/PTM_RATIO;

    _body->ApplyForce(b2Vec2(-5.0f*diff.x,5.0f*newP.y), _body->GetPosition());

    [arrTouches removeAllObjects];

}

在box2d iphone中拖动指针和跳跃体

1 个答案: