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fixed update and time.deltatime
hi im newish to unity and wanted to clarify something i read online.
in fixed update i do not need to put time.deltatime, due to the fact this is physics timestep already, so its kind of pointless.
however in an update function i should use this if my code requires physics as update is per frame, and thus performs differently per computer frame rate.
am i right or wrong cheers...
Answer by keld-oelykke · Mar 30, 2012 at 10:50 PM
"in fixed update i do not need to put time.deltatime, due to the fact this is physics timestep already, so its kind of pointless."
Time.deltaTime is NOT the physics timestep.
Time.deltatime (duration of last frame) should only be used in once per frame calls e.g. Update() calls.
Time.fixedDeltaTime should only be used in FixedUpdate(), since it the sample time of the physics loop.
Note! You can set fixedDeltaTime and a deltaTime cap in the Time manager.
Here is Unity's explanation of above.
"however in an update function i should use this if my code requires physics as update is per frame, and thus performs differently per computer frame rate."
The physics loop is called a fixed number of times per second (constant fixedDeltaTime) and Update is called a variable number of times per second (a non-fixed deltaTime). So, yes, you make calculations time independent in the Update-call and the FixedUpdate() by using Time.deltaTime and Time.fixedDeltaTime, respectively.
Cheers, Keld
cool i was on the right tracks then, i did wander why when i used time.deltatime in fixed update it was still effecting my object and now i know why.
Also handy to know: according to the script reference, Time.deltaTime
will return fixedDeltaTime
when called during FixedUpdate()
.
What if i write a for loop where some lines need to be executed in fixed time and some in not fixed, should i just write this in Update() and then use time.deltaTime and fixedDeltaTime , because splitting it up seems quite complicated O:-)
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