如何获得 Phaser3 精灵顶部的坐标？

Question

I'd like to find out a top coordinate of a snippet. The idea is to make a line between a point and the top of the green element.

How can I find or calculate this coordinate. I know the size of the box and angle.

Here is a source code where I create a purple line.

Here is a gif example.

Thanks!

Answer 1

As fas as I understand, rotation center cx, cy should be at the top of rope.

Top point of the net has coordinates

tx = cx + ropelen * Cos(angle)
ty = cy + ropelen * Sin(angle)

If base point of sprite differs from top point, but lies below by dy , you can find its coordinates with the same formula using ropelen + dy

If base point of sprite differs from top point, but lies left by dx , you can find its coordinates with the same formula using sqrt(ropelen^2 + dx^2 ) and angle angle + atan(dx/ropelen)