Question

I want to move an object on a circle around a given point. I am using OpenGL on Android and my viewport is the screen resolution in landscape mode (1280 * 800). The point I want to rotate an object around is e.g (500, 300) and this is where the user pressed. I also have the radius of the desired circle r.
To sum it up, I’ve the center of the circle, the radius, and the angle (amount I want to move the object with each iteration of the game loop)

So far I tried this:

this.setPosX(((float)Math.cos(angle)*radius + center.x) * width);
this.setPosY(((float)Math.sin(angle)*radius + center.y) * height);

This will create a movement along an ellipsis, not a circle…

Can anyone please help me?

Answer 1

It produces an ellipse cause circles DON’T have heights. Try this instead

this.setPosX(((float)Math.cos(angle)*radius ) + center.x);
this.setPosY(((float)Math.sin(angle)*radius ) +center.y);