Canvas move object in circle

canvas, html, javascript

Solution

The parametric equation for moving in a circle is this:

x=r*cos(theta)
y=r*sin(theta)

`theta` is the angle, and `r` the radius.

If you want to know the change in `theta` to get the desired speed, solving for the distance `d` you get that the change in `theta` is: `arccos(1-(d/r)^2/2)`

The JavaScript functions are Math.cos, Math.sin, and Math.acos, respsectively. They all deal with radians.

Problem

I have a rectangle in canvas, and I know how to move it up and sideways. What I want to do is have it move in a circular motion. So my objects(rectangle) x and y would go in a circle. Now I am assuming I need a radius for how far out and some formula for the speed(1pixel) to get it rotate on the axis. Any idea's?

Original source