Custom LookAt Function Help

[wbourassabennett]

Hello!

I’m trying to get a quaternion (or Euler, whichever is easiest / most performant) from 2 points in space, where the right component(red gizmo arrow) of the rotation is the direction of one point towards another with the forward component (blue gizmo arrow) facing upwards: where the up component (green gizmo arrow) is perpendicular to a flat plane. Essentially the result of a transform.LookAt() function where forward is right and up is forward.

I’m using ECS (float3, lower-case quaternion), so I can’t use external functions. I’ve included an image to hopefully make a little more clear what I’m trying to achieve.

Thanks!

[spiney199]

Probably just need Quaternion.LookRotation: Unity - Scripting API: Quaternion.LookRotation

You can specify an up-direction for the rotation.

[Ryiah]

@wbourassabennett

I’m using ECS (float3, lower-case quaternion), so I can’t use external functions.

Here are the ECS equivalents to the above method:

https://docs.unity3d.com/Packages/com.unity.mathematics@1.3/api/Unity.Mathematics.quaternion.LookRotation.html
https://docs.unity3d.com/Packages/com.unity.mathematics@1.3/api/Unity.Mathematics.quaternion.LookRotationSafe.html

[wbourassabennett]

The problem with LookRotation, is the forward vector is always the “z” component (the blue gizmo arrow on the object points towards the target), while what I am trying to achieve is have the “x” component (red gizmo arrow) point towards the target. Changing the world up parameter doesn’t change this.

[spiney199]

Then you just need to apply an additional rotation to the object after you’ve got your look rotation.