Hello, I’m so new at Unity engine. 
I’m trying to make demo version of 3d running game, so my character stays at some point and whole map is moving toward it.
I’m trying to test jump and double jump via rigidbody(3d)'s velocity, and it seemed work well at first.
But, somehow it turned out that jump height is changes depending on character’s current position(altitude).
If my character stands at higher grounds, jumps lower. If character stands at lower places, jumps higher.
At first when I setting jump forces, I setted second(double) jump force slightly bigger than the first one because if I set two forces(velocities) same, the second jump height is lower than the first one.
First I thought that was because second jumping was offsetted by first jump’s moving velocity(or force).
Now I guess that was because second jump performs at higher altitude than the first jump…
Why is this happening? And what should I do to fix this, to jump same height no matter where my character is?
please, please let me know.