Bouncing Ball. Making it slow down at peak of height

Question

I have created a bouncing ball animation in x3d. I am just curious how I could make the ball slow down at the peak of its height to make it look more realistic. Thank you in

Answer 1

Use 'real' physics for that.

1. ball have parameters

   • acceleration a(ax,ay,az) [m/s^2]... this is sum of all forces driving ball divided by its mass
   • velocity v(vx,vy,vz) [m/s]... actual speed = integration of acceleration v += a * dt
   • position p(x,y,z) [m]... actual position = integration of velocity p += v * dt
   • radius r [m]
   • mass m [kg]
   • dt [s] ... iteration step (update time)

   init start a,v values to (0,0,0) and p to start position

2. apply gravity, friction, collision

   • gravity for example g(gx=0,gy=-9.81,gz=0)
   • friction f2 = -(|v|^2)*c2 * (v/|v|) ... in gas
   • friction f3 = -(|v|^3)*c3 * (v/|v|) ... in liquid

   if position before and after cross collision border reflect velocity * collision coef <=1 by impact normal also you can reflect position if crossing border is not possible.

3. put it all together in some timer / updating code with dt interval

   a =g+(f2+f3+(driving force))/m
   v+=a*dt
   p+=v*dt
   test_collisions()
   redraw()
   

4. for manual change of position

   just set p(x,y,z) to new position and also can set v=(0,0,0) to stop the ball