I have a ball game object that I am making bounce using explicit physics equations. I tried using unity's physics engine, but It was not exact enough. I am setting the balls position like so:
float dTime = Time.time - timeSinceBounce;
ballPosition.x -= meterOffset / sensitivity;
ballPosition.y = ballInitialPosition.y + GameConstants.Instance.GetBallYVel ()
* dTime - (float)0.5 * GameConstants.Instance.GetGravity () * dTime * dTime; //Yi+Vy*t-0.5(G)(time^2)
ballPosition.z = (-dTime * GameConstants.Instance.GetBallZVel ()
+ ballInitialPosition.z) * startConstant; //Zi + t*Vz
ball.transform.position = ballPosition;
This code runs in the Update() method. When a collision is detected the time and initial position as reset, and this works. Currently the ball bounces properly but shakes when it is moving quickly. The FPS is at 80. I don't think my equations are wrong because it bounces properly there is just a shake. What is the best way to remove the shake? Thank!
Edit 1: I decided to write my own physics because Unity's physics engine had a lot of other components like friction and roll that were making the ball's bounces vary. Also the camera's x and y is fixed the only thing that is changing is the camera's z position. It works a lot better in fixed update
As of asker's request I hereby add all the details I can, even though without seeing the actual, full and complete code along with seeing this "shake" effect it's challenging to give an exact and proper answer. I'll try and do my best though.
So let's do this.
1. "Shaking" reason: most probably you set up some kind of animation, along with a forced positioning/rotation/etc and these two codes work against each other. Double-check your AnimatorController and Animator as well as your Mecanim if you have set/configure these (also a good read: "Locomotion").
You can also keep the Animator Window open while you are testing from Unity UI, to see who is the tricky guy doing the "shaking" effect for you, and get one step closer to why it happens.
If these don't help, start from scratch: Minimize the code you wrote to move the ball, remove every effect, etc and add them back one by one. Sooner or later "shakieness" will come back (if it persist with the cleanest possible code, see above, Animator/Locomotion issue)
2. Think again not rewriting Unity Physics... You mention for example
"...physics engine had a lot of other components like friction and roll that were making the ball's bounces vary...".
Now, this is something you can turn off. Completely if you want. Easiest way is to set everything to zero on Physics Material (i.e. friction and bouncieness) but if you want Unity to ignore all and every "actual physics" and let you do what you want with your GameObject, tick in the isKinematic property of the Rigidbody. The fun part of it, you'll still collide if and where you want, can AddForce, etc yet neither gravity nor friction or "anything physical" affect you.
If you are not comfy with Unity (and you are not it seems), I highly recommend learning about it a bit first as it is a very good and very powerful engine - so don't throw it's features away as they don't work as you initially expected they'll do. For example, Sebastian Lague just started a great beginner series a few weeks ago. The guy is a teacher, his videos are both short, fun and full of information so I can just recommend his channel.
3. As of your code I would make these changes:
public static class GameConstants { //no monobehaviour == can be a "proper, global" singleton!
public static float GetGravity {
get { return [whatever you want]; }
//why not Physics.gravity, using locally when and where it's needed?
}
//etc, add your methods, properties and such
//use this approach if and only IF you access these values application wide!
//otherwise, instead of a """singleton""" logic you just implemented,
//consider adding an empty GameObject to the Scene, name it "GM" and
//attach a "GameManager" script to it, having all the methods and
//properties you'll need Scene-wide! You can also consider
//using PlayerPrefs (see help link below) instead of a global static
//class, so you save memory (but will need to "reach out" for the data)
}
private void FixedUpdate() { //FIXED update as you'll work with physics!
//float dTime = Time.time - timeSinceBounce; //not needed
//positioning like this is not recommended, use AddForce or set direction and velocity instead
ballPosition.x -= meterOffset / sensitivity;
ballPosition.y = ballInitialPosition.y + GameConstants.Instance.GetBallYVel ()
* Time.fixedDeltaTime - 0.5f * GameConstants.Instance.GetGravity () * Time.fixedDeltaTime * Time.fixedDeltaTime; //Yi+Vy*t-0.5(G)(time^2)
ballPosition.z = (-dTime * GameConstants.Instance.GetBallZVel ()
+ ballInitialPosition.z) * startConstant; //Zi + t*Vz
ball.transform.position = ballPosition;
}
BUT to be honest,
I would just throw that code away, implement the Bouncing Ball example Unity Tutorials offer, alter it (see point #2) and work my way up from there.
Items not linked but I mentioned in code:
PlayerPrefs, Physics.gravity and Rigidbody.velocity.
Note that 'velocity' is ignoring parts of physics (speeding up, being "dragged", etc) i.e. objects suddenly start moving with the speed you set (This is why Unity5 recommends AddForce instead -linked above-)
It might also come handy you can alter the FixedUpdate() frequency via Time Management, but I'm not sure this is yet needed (i.e. just for bouncing a ball)
I hope this helps and that ball is going to bounce and jump and dance and everything you want it to do ;)
Cheers!
