ohhh, im very sorry, i overstepped your suggestion
but i didnt really get the clue. you have to explain it carefully.
- check for collision:
yes, thats the main problem. do you mean a precollision over bounding boxes ?
- normalize the speed vector
up to now i realize movement over an always normalized direction vector and a speed scalar
- backtrace trajectory
sure, but the question is, with which method ?
for tracing the collision point (and later calculating the gradient of the small surface) i only see the method of line intersection