Comments and answers for "How can I make a physics base projectile move along the path of a sphere?"
http://answers.unity.com/questions/1436425/how-can-i-make-a-physics-base-projectile-move-alon.html
The latest comments and answers for the question "How can I make a physics base projectile move along the path of a sphere?"Answer by Glurth
http://answers.unity.com/answers/1436433/view.html
Based on the velocity and mass of the bullet, you can apply a force towards the center of the sphere, each frame. This is how orbits work.
(This would not put it "on-rails" though: That term usually means ignoring game-physics.)
To compute the force needed:
from wikipedia https://en.wikipedia.org/wiki/Orbital_speed
V = Sqrt(GM/r)
`V` will be the initial speed of the bullet.
`r` will be the distance between the bullet and the center of the sphere
Solving for `GM` we get:
GM = V^2 * r
`GM` is part of the formula for gravitational force:
F=GMm/r^2
Where lowercase m is the mass of the bullet.
Plug in our expression for `GM`:
F= V^2*r * m / r^2 = V^2*m/r
So `V^2*m/r` is the magnitude of the force you need to apply, towards the center, to a bullet of mass `m`, for it to orbit at a radius of `r`, moving at (linear) velocity `V`.Tue, 28 Nov 2017 21:15:04 GMTGlurth