Calculate spaceship speed with distances

Hello,
In my game, I want to know the speed of my spaceship in relation to the planet like in outer wilds.

(Like the 62m/s)

I used : (lastDistance - distance)/Time.deltaTime
Where distance is : (myPlanet.transform.position - ship.position).magnitude

It works well when I don't accelerate, but the result is very big when the spaceship accelerates.
And when I stop accelerating the result is normal again.

Can you help me, I spent a long time trying to find a solution?

 

What you have above should be fine, modulo the noise of the frame interval, which even then should be minimal as long as Time.deltaTime was used for the actual movement in the first place.

The only way I can see odd values is if you are updating position in physics and checking this in Update().

If you are moving it via physics, the above code would need to go into FixedUpdate() otherwise bad stuff might happen.

Good discussion on Update() vs FixedUpdate() timing:

https://jacksondunstan.com/articles/4824

Here is some general timing diagram help:

https://docs.unity3d.com/Manual/ExecutionOrder.html

If you are still not getting what you want, time to debug. You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

 

Thank you verry much for your answer.
I found the solution.
I just created a new script only for the speed calculation and I don't know why but now it works.
May be the other things in my script created a latency in the update() and it was impacting the calculations.