Flick motion for iPhone

Question

Hi all, I am in the process of developing a project that will require the flicking or FLICK MOTION of an object such as a ball...obviously it will have to travel through a trajectory based on the position and the path travelled by the finger on the iphone screen...Please can anyone help me out with the code or how to go about getting this physics sorted as I am lost. Thanks.

Answer 1

Motion is defined by Newton's laws of physics. In particular, F = ma, which is equivalent to d²p/dt² = F/m. If you don't know calculus, this will be a little tough to grasp.

The i-just-want-it-to-work answer is to use a regular time quantum (1/60 s is common for game engines), during which you use the acceleration due to gravity to update the velocity, and the velocity to update the position:

dt = 1.0/60.0;
v += g*dt;
p += v*dt;

This is done using vector arithmetic, so in practice (unless you write or steal a C++ vector library) you'll end up writing something like v = vec_add(v, vec_mulf(g, dt)).