Question

我正在尝试创建一个圆形体/形状并将其挂钩到UIImage，这是一个带有透明背景的.png，只是一个简单的圆形，大小为60 x 60像素。

我正在使用下面的代码来做它，并且它工作正常，除了在圆形图像周围似乎有一个看不见的更大区域（即圆形图像的两侧不能接触其他对象，如圆形体/形状较大。我不知道为什么会发生这种情况，因为我在所有测量中都使用了60px的半径等等。代码在下面，任何想法有什么不对？

- (void) createCircleAtLocation: (CGPoint) location
{
    _button1 = [[UIButton alloc] init];
    _button1 = [UIButton buttonWithType: UIButtonTypeCustom];
    [_button1 setImage: [UIImage imageNamed: @"ball.png"] forState: UIControlStateNormal];
    _button1.bounds = CGRectMake(location.x, location.y, 60, 60);
    [self.view addSubview: _button1];

    float mass = 1.0;
    body1 = cpBodyNew(mass, cpMomentForCircle(mass, 60.0, 0.0, cpvzero));
    body1 -> p = location; // Center of gravity for the body
    cpSpaceAddBody(space, body1); // Add body to space

    cpShape *shape = cpCircleShapeNew(body1, 60.0, cpvzero);
    shape -> e = 0.8; // Set its elasticity
    shape -> u = 1.0; // And its friction
    cpSpaceAddShape(space, shape); // And add it.
}

Answer 1

在这种情况下，'隐形区域'是形状。形状由其半径定义。如果您有60x60图像，半径为30而不是60.使用新半径更新形状和主体，它应该可以正常工作：

- (void) createCircleAtLocation: (CGPoint) location
{
    _button1 = [[UIButton alloc] init];
    _button1 = [UIButton buttonWithType: UIButtonTypeCustom];
    [_button1 setImage: [UIImage imageNamed: @"ball.png"] forState: UIControlStateNormal];
    _button1.bounds = CGRectMake(location.x, location.y, 60, 60);
    [self.view addSubview: _button1];

    float mass = 1.0;
    body1 = cpBodyNew(mass, cpMomentForCircle(mass, 30.0, 0.0, cpvzero));
    body1 -> p = location; // Center of gravity for the body
    cpSpaceAddBody(space, body1); // Add body to space

    cpShape *shape = cpCircleShapeNew(body1, 30.0, cpvzero);
    shape -> e = 0.8; // Set its elasticity
    shape -> u = 1.0; // And its friction
    cpSpaceAddShape(space, shape); // And add it.

}

用Chipmunk物理创建一个圆，但是半径太大了？

1 个答案: