Draw an arrow between two circles?

Question

How can I draw an arrowed line between two circles, given:

1. Location of the centers of the cirlces
2. Radius of the circles

I am using

Answer 1

If I understood correctly, you need to find the 2D vector that you need to add to the source to get to the border of the target circle.

Pseudo code:

d = distance between A and B; // (sqrt((xB-xA)² + (yB-yA)²)).
d2 = d - radius;

ratio = d2 / d;

dx = (xB - xA) * ratio;
dy = (yB - yA) * ratio;

x = xA + dx;
y = yA + dy;