Hello!
For my 3D game project, I want to be able to predict where a projectile will land so I can display an indicator on that predicted position.
As a run-through of what I've tried:

• simulate physicsprocess
• simulate a RigidBody3D with `test_move`/`move_and_collide`
• followed a few cannon Unity tutorials which are supposed to simulate projectile motion (but none seem to give me the result I desire except for in 2D).

As none of these have worked, I've moved onto projectile motion equations. I would like to know if there's either a way to fix my issues around the equations or if there is a better way to approach this problem. I would like to note that I am using `PhysicsDirectSpaceState3D.intersect_shape(query)` on a sphere with a radius of ~2, where I translate the `query` by the points as they're calculated in order to figure out if it has collided, and then I use `get_rest_info(query)` to find the collision point.

Here is my current approach using these projectile motion formulas -
(`v0=initial velocity Vector3`, `t=time/simulated time passed`, and `g=gravity`)
`x = v0.x * t * cos(theta)`,
`y = v0.x * t * sin(theta) - 1/2 * g * t^2`, and
`z = ????`
A few problems with this though is: I have no idea how to calculate the `z` nor how to get the `theta`.
I seriously do not know how to even approach calculating the `z` and after many hours of looking at kinematic equation explanations, I feel even more lost. So many people online say that the third dimension is easy to calculate but no one seems to explain how.
I am also unsure of how to actually find the `theta` in a 3D space. Would the `theta` be `start position vector3.angle_to(launch velocity vector3)`? Using the `start_position` as the `local_position` of the player (which is Vector3.ZERO) makes the angle 0 which obviously isn't helpful. Would the Vector3 `global_position.angle_to(to_global(launch velocity))` solve this?

I'm unsure of how to attach a project so I've tried to supply as much as possible here:
Player.gd script with the main projectile prediction script:
https://pastebin.com/GGnuGuBi (from a unity tutorial follow along)
https://pastebin.com/hurQiLSi (my current attempt)