algorithms_edu/algo/geometry/
tangent.rs

1use super::{Circle, Point2D, SafeArcSinCos, EPS};
2
3pub enum TangentError {
4    PointInsideCircle,
5    PointOnBorder,
6}
7
8impl Circle {
9    pub fn tangent_points(&self, point: &Point2D) -> Result<[Point2D; 2], TangentError> {
10        let d = self.center - point;
11        // the distance to the circle center
12        let dist = d.magnitude();
13        if dist < self.radius + EPS {
14            return Err(TangentError::PointInsideCircle);
15        }
16        if dist < self.radius + EPS {
17            return Err(TangentError::PointOnBorder);
18        }
19
20        let angle1 = (self.radius / dist).acos_safe();
21        let angle2 = d.x.atan2(d.y);
22        let angle = angle2 - angle1;
23
24        let p1 = Point2D::new(
25            self.center.x + self.radius * angle.sin(),
26            self.center.y + self.radius * -angle.cos(),
27        );
28        let p2 = Point2D::new(
29            self.center.x + self.radius * -angle.sin(),
30            self.center.y + self.radius * angle.cos(),
31        );
32
33        Ok([p1, p2])
34    }
35    // pub fn tangents(&self, point: &Point2D) -> Result<>
36}
algorithms_edu/algo/geometry/tangent.rs

algorithms_edu/algo/geometry/
tangent.rs
