koobas.hobune.stream
C# | How to disable gravity for a certain amount of time?
Okay, so I'm making my own jumping script ( a very simple one), and I need to disable the gravity feature for like maybe 0.5 or 1 second for it to work. I just don't know how to do it. Also, I'm a beginner so please explain in depth what's happening in the code so that I can understand.
void Update () {
if (Input.GetKey (KeyCode.Space))
{
transform.Translate (Vector3.up * 5 * Time.deltaTime);
}
}
This seems like a strange way to implement a jump, normally gravity doesn't disappear as you leap into the air! But if that is what you want to do, use a coroutine. A coroutine just allows you to run a second lot of code 'parallel' to the other code being executed, rather than the usual, one method, then the next. Note that the code here doesn't run in a new thread, it simply 'saves' its state at the end of each frame, and continues where it left off in the next one:
bool isJumping = false;
Rigidbody rb;
void Update(){
//some code
if(someAction && !isJumping){ //if someAction was performed and we are not already jumping, start!
StartCoroutine(Jump(rb));
}
}
IEnumerator Jump(Rigidbody rigidbody){
isJumping = true; //make sure we can't jump whilst already doing so!
bool oldGravity = rigidbody.useGravity; //save our old gravity
rigidbody.useGravity= false; //set gravity to 'not used'
float timer = 0.5f //set the time for which to hold gravity off
while(timer >= 0){
//do some jumping stuff
timer -= Time.deltaTime; //minus the time that the frame took, from our timer i.e. count down
yield return null; //move to the next frame
}
//our time is up
rigidbody.useGravity = oldGravity; //set gravity back to normal
//might want to wait until we hit the floor again or something, before allowing ourselves to jump again
isJumping = false;
}
Using Translate for movement with when physics is involved is generally a bad idea. Secondly, turning off gravity, will effect ever rigidbody's gravity, not just the player that is jumping... more design floors, best just to use AddForce or similar, or set rigidbody.velocity over the course of a few frames if you really want a set ascent speed.
Anyway... you have been warned!
for your 0.5 second requirement you will need a Coroutine
Thank you very much, but also is there a better, more efficient way of doing it? Thanks.
I suggested some alternatives at the bottom of my answer, for a similar effect, you simply set the rigidbodys velocity in a coroutine, and use
yield return new WaitForFixedUpdate();
ins$$anonymous$$d of yield return null, so that the physics changes are correctly implemented.
As another potential option, if you're looking to jump up to a specific height rather than jump for a fixed length of time (or it can be both, really), you can calculate the physics force required to reach that height using:
float gravityStrength = Physics.gravity.magnitude; // Usually 9.81
float jumpHeight = 5.0f; // How many meters/units do you want to jump up?
float jumpForce = $$anonymous$$athf.Sqrt(2 * gravityStrength * jumpHeight);
If you use Physics.gravity doesn't everything 'jump'? Surely you want to disable Use Gravity on the rigidbody.
Strange jump technique :P
indeed, I should probably change that, I didn't really think, the whole idea seemed strange. I'll edit now! Could make for quite fun gameplay however!
