Need examples of spinning circle around an object.Unanswerd

[cameron]

Hello everyone.I need to make a circle spin for one of my games I know how it might work. But I need some examples of a spinning circle sorce code.Any comments are appriciated. Thanks chili for all your hard work.

[LuX]

How do you mean spin?

With like an image in the middle like a wheel or some kind of a physics thing or what? Be more specific.
Generally a blank circle is already "spinning", depends how you imagine it.

[cameron]

Ok sorry Lux I mean i have a circle drawn and I want that circle to move around in a circle.In other word I want a circle to spin around an object.

[Lorth]

Like the moon circles around the earth?

[LuX]

Or like the sun circles around the earth?

...Wait what?

I think the answer can be found on multiple topics on planet chili, but it shouldn't be too hard to search from the web.

[chili]

You need to make an angle variable, and then every frame you increment the angle and then rotate the coordinates of the circle by the angle.

The transformation is:

x' = x cos(a) - y sin( a )
y' = x sin(a) * y cos( a )

Google rotation transformation and do some research if you are still clueless.

[XxWalKaxX]

what includes are needed for trig operations, math.h??

[LuX]

Yeah, but since were into C++ stuff, use <cmath> instead. No real difference between 'em.