我的游戏中的圆形碰撞比图像稍大

Question

I'm implementing circular collision in my game made in Go using a simple rendering framework called Pixel.

The collision works fine with shapes like a drawn circle

But when I try to use it with an image instead of a rendered shape, it thinks it collides slightly before it reaches the image. The larger the image, the larger the error.

Here is where it collides on the images:

Smaller image:

Larger image:

The collision is done like so:

[s being the solar panel, seen in the "smaller image", and p being the player.]

math.Pow(math.Pow(s.center.X-p.center.X, 2)+math.Pow(s.center.Y-p.center.Y, 2), 0.5) <= s.size.X

The size.X and size.Y of each image is the same since it's a circle

The centers are calculated correctly and this exact line works with shapes [you can see the yellow outline in the first image, that's the shape it works with.]

Am I doing something wrong? Why would there be an error caused by this when the calculation has nothing to do with the image itself?

Here's how the images are rendered, I assume the problem lies with that somehow:

[g being the generator, seen in the 'Larger image'

func (g Generator) render(win *pixelgl.Window, imd *imdraw.IMDraw) {
    mat := pixel.IM.
        Moved(g.center)
    g.sprite.Draw(win, mat)
}

The shape is drawn based on it's center as well.

Answer 1

If both colliding objects are circles with radii R1 and R2, then collision occurs when

math.Pow(math.Pow(s.center.X-p.center.X, 2)+math.Pow(s.center.Y-p.center.Y, 2), 0.5) <= 
 s.radius + p.radius

What is s.size - image square side? In this case you have to use size/2 to get radius.
Why do you ignore size/radius of p?

These two reasons together might cause described behavour (collision condition fires when center-center distance becomes equal to s side size)