Don't understand Input Axis * Delta Seconds

[David_Eirich]

I’m really having trouble understanding the reasoning behind lecture 110’s blueprint setup for camera angle control that multiplies the input axis by the delta time in seconds.

I printed out the input axis to see that it’s not the absolute axis, but just the delta angle. It stays “0” when the mouse isn’t moving, and changes to small values like 0.5 or -0.5 as you move the mouse.

What is the point of multiplying a delta angle by a delta seconds? Why even multiply two different types of units, angle and time? Is this multiplication something that we should always be doing when rotating a camera, or rotating anything based on user input?

This is somehow supposed to help with different frame rates. Can anyone help explain this to me?

Thanks!

[DanM]

It’s to make the rotation frame rate independant. Say if the axis value was 1, at 10FPS that would mean moving at 10 degrees per second, at 100FPS, 100 degrees per second.
Multiplying by the delta time and our set rate (100) means we can adjust for frame rate.

[Levani_Pirtskhalava]

Hello Dan!

1. what’s wrong if Camera rotation is dependent on Axis value. it’s the same result in runtime process as it was in the lecture?

2. what is different between 1 and 2. we can search mouse-x in Blueprint without doing it from Project Settings?
3. if I connect only Get World Delta Seconds to AddLocalRotation node ( without Axis Value) in RunTime process Camera straightway start rotation. why it’s not waiting executable button, because for the execute AddLocalRotation it’s need to move mouse?

[DanM]

what’s wrong if Camera rotation is dependent on Axis value. it’s the same result in runtime process as it was in the lecture?

Not sure what you are talking about

what is different between 1 and 2. we can search mouse-x in Blueprint without doing it from Project Settings?

The first would be the equivalent of hardcoding something. Setting it up in the project settings allows you to configure the bindings

if I connect only Get World Delta Seconds to AddLocalRotation node ( without Axis Value) in RunTime process Camera straightway start rotation. why it’s not waiting executable button, because for the execute AddLocalRotation it’s need to move mouse?

For Input Axis (as opposed to Input Action) it’s firing every frame.

[Levani_Pirtskhalava]

1. I mean to build the code as it is showed in photo. Is something wrong to connect axis value to AddLocalRotation directly without Delta Second
2. why the first Hardcoding?
   second allows us binding to C++ opposite the first, is not it?

[DanM]

1. Incorrect for mouse control to * DeltaSeconds, Correct for analogue stick.
2. Because the first says “Mouse X” which is a specific input, 2nd is configurable in the project settings and game if you set that up.

[Levani_Pirtskhalava]

thank you