Trying to interpolate camera movement

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1

Godot Version

4.4

Question

Hi guys. I’m trying to interpolate this line:

HEAD.rotation_degrees.y -= mouseInput.x * mouse_sensitivity

using lerp:

HEAD.rotation_degrees.y -= lerp(HEAD.rotation_degrees.y, mouseInput.x * mouse_sensitivity, cameraAcceleration * delta)

It moves smoothly, but as soon as I stop moving the mouse, the camera returns into its original position. Could someone help me, please? Thank you so much.

2

I could be wrong, but I don’t think you’re supposed to subtract the result you get back from lerp at all. Try to simply SET the value instead of subtracting it.

3

I’m subtracting it, because otherwise the camera would rotate at the opposite direction than the mouse movement.

4

Then your lerp should target -mouseInput.x * mouse_sensitivity, but I think this isn’t what you want either.

Lerp takes the first and second argument and returns a value between the two, based on a percentage supplied by the third argument.

lerp(0, 100, 0.25) == 25
lerp(50, 100, 0.5) == 75

This is often miss-used to smooth movements by supplying the current position (your case rotation) for the first and a target for the second. The third argument only has to be a number lower than 1 and greater than 0 to produce a smooth, but frame-dependant result, multiplying by delta actually makes this frame-dependency significantly worse.

If you want to continue working with lerp you need to define a target rotation much like you applied the initial rotation, then use that as the second argument.

var target_rotation: float = 0.0 # in class body

# in input/process function
target_rotation -= mouseInput.x * mouse_sensitivity
HEAD.rotation_degrees.y = lerp(HEAD.rotation_degrees.y, target_rotation, 0.1)
2 Likes
5

Thank you, but the first row

target_rotation -= HEAD.rotation_degrees.y -= mouseInput.x * mouse_sensitivity

gives me “Assignment is not allowed inside an expression.” error. Unfortunately, I’m rewriting a player script/plugin, which involves much more I’m able to handle :-/

6

Sorry, must’ve missed that in the copy-paste, edited the fix.

1 Like
7

Thank you so much. Now I’m going to analyse, what did you do :smiley: