Distance between center to any point on edge of rectangle in javascript

问题

As you can see in above picture, suppose that there is a ray emitted from center and collides at edge of rectangle. so I want to calculate at which point it collides, so that I could be able to calculate distance between point on edge and center.

• What we know?
  • width and height of rectangle
  • a degree & b degree (as shown in above figure)
  • centerX, centerY

回答1:

Let's center is (0, 0) and ray angle is phi. Pseudocode:

c = Cos(phi)
s = Sin(phi)
if Width * Abs(s) < Height * Abs(c) then
   x = Sign(c) * Width / 2
   y = Tan(phi) * x
else
   y = Sign(s) * Height / 2
   x = CoTan(phi) * y

来源：https://stackoverflow.com/questions/39055985/distance-between-center-to-any-point-on-edge-of-rectangle-in-javascript