CODEWITHSUNDEEP
c#unity-game-engine
isNull
isNull

Reputation: 13

(Unity) Issue with rotation when transform.up is aligning to a direction

I am testing out some ideas in Unity where a player can walk around a circle while staying on it (so the circle has its own gravity) and also being oriented properly. This game is currently being done in 2D, so all objects are sprites.

I do hope I can explain myself properly. Please ask if you need any further clarification...

It appeared that I succeeded with my idea until I noticed something odd.

So as expected, the player moves around the circle without falling off (custom gravity worked just fine) and its Z rotation is affected as it aligns itself with a direction:

// Align code:

// We reverse the direction so the object is standing up the right way.

private void Update()
{
    transform.up = -(planet.position - transform.position); 
}

It works... mostly. However, when the player object's rotation Z naturally reaches 180, it appears to flip horizontally (like a mirror effect) and then it returns to normal as rotation Z leaves 180. The visual flip happens because for some reason the object's Y becomes 180 at the same time too. At no other point does X or Y change in regards to rotation. Only Z. So the moment Z hits 180, Y is affected and the moment we leave Z 180, Y returns to 0.

I'm happy to provide a quick video of it happening in-game if anybody needs some visual understanding of what's going on.

The visibility of this bug tends to rely on how fast you're moving around the circle. If you're moving fast enough, you can probably skip over 180 and not see it happen at all, however if you move slow enough there's no denying it's there. It's also problematic for the fact that I simply make the camera a child of the player so when the player flips, so does the camera causing the entire scene to flip which can look extremely glitchy for a player to see.

I really have no idea how to tackle this issue as I have no clue why it would do such a thing. At every other rotation value it behaves just fine. It's only at Z = 180 (so the object is exactly upside down) does it decide to rotate in the wrong ways.

EDIT: Changed tag to Unity3D

Upvotes: 1

Views: 1582

Answers (1)

C-JARP
C-JARP

Reputation: 1088

It's probably because of converting quaternions (which is what's actually used internally for rotations) to euler angles for display. Can you try to use Quaternion.Slerp to rotate?

Upvotes: 0

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