I am fond of creating graphics and animations using the frameworks on the iOS platform; lately, I discovered that, in order to create better visual designs, those higher-level of frameworks do not provide enough controls to satisfy the needs of creating more advanced-level designs. Hence, I decided to invest my time in studying OpenGL ES.
Whilst doing so, I came across the ray-tracing topic; I have spent quite a bit of time studying the mathematics and topics related to it. And, I have been able to render simple stationary objects (geometrically) using this technique.
In order to learn deeper, I started to toy around with the idea of allowing these objects to have movements based upon user-interactions (I.e., when the user moves the object on the screen with her finger, the corresponding object will spin around or simply move to the respective location based upon the user's touch (on mobile device)).
According to what I have studied thus far on ray-tracing, however, this operation of allowing the objects to move based on user-interactions could be very costly in ray-tracing. To me, for example, it would mean that, if a rendered sphere were to spin around based on user's touch on the screen, I would need to ray-trace the whole sphere for every frames as the sphere spins.
Is my understanding correct here?
My question is, is it possible to perform ray-tracing on objects that are movable; if so, is there another ray-tracing technique specialized especially for this purpose, which could be less costly? Or, is ray-tracing more suitable for rendering only architectural objects, which are usually stationary?