# Quad Interpolation in Blueprint ?

Hi, is there any way to turn on quad interpolation in Blueprint, I have a lerp rotating an object but after turning two times it rotates off on a strange angle.

I saw there was a question submitted similar to this nearly a year ago but I can’t find an update since,

Hello,

could you specify the issue a bit further? So far, I haven’t heard of any qarp nodes within blueprints, so maybe there is a different work around to your problem?

Basically I’m trying to rotate an object a number of times, adding 90 degrees every time there’s an input. This is a screenshot of the blueprint.

When the player presses F for the third time the mesh rotates of on a ridiculous angle much like what some objects in UDK used to do in Matinee when Quad Interpolation wasn’t active. My designer friend glanced at it and thinks it’s because I need to active Quad interpolation somewhere within the blueprint. Any ideas ?

I have the whole system working in a different blueprint but this is just refining it and making it a lot more concise and less complex.

It’s hard to tell what the problem is without a video, but maybe your friend means “quat” interpolation? If so, check “shortest path” on the Lerp node to use quaternions rather than rotators.

If you actually mean “quad” as in “quadratic” interpolation, you can look into using the “EaseFunc” nodes or use iTween

Hey again,

I got a slightly more complex work-around by creating 2 floats that control the pitch of the object. This solution is not optimal, unless you restrict the player to only be able to rotate the object by 90 degrees. As it is right now you could press the F button at any time (even while the object still rotating) and it would add 90 degrees onto the pitch as it is at that current point in time.

To prevent this you can add a simple boolean at the start, which checks if the object is being rotated. For that simply set the boolean to true once the timeline starts playing and then set it to false when the timeline is finished.

EDIT: resetting the pitch once it reaches 360 is also optional. You can have the pitch set to 720 or even higher and it would still work fine, however it would eventually reach a ridiculously high number and I am not sure if this could cause issues (therefore I decided to reset it).

Hi everyone,

DanSaxon is correct. Basically you will have to convert the rotator to quarternions to move past gimbal lock. You can find additional information on Gimbal Lock here:

Additionally, you can find information on quarternion mathematics here: