koobas.hobune.stream
Lookat on local axis
I have an object that must face another on it's local z axis only. Only the local z euler rotation will be modified.
I've seen a few other similar questions, but each answer had a small problem. Here are the three main (incorrect) methods:
Method 1:
Vector3 curRot = transform.localEulerAngles;
curRot.y = 90;
curRot.z = 0;
Vector3 dirToCamera = (camera.position - transform.position).normalized;
float xDir = Quaternion.LookRotation(dirToCamera).eulerAngles.x;
curRot.x = xDir;
transform.localEulerAngles = curRot;
This doesn't work because xDir is not signed, causing the rotation to only work from one side. On the other, the rotation will be inverted.
Method 2:
// look at camera
Vector3 camRot = camera.position;
Vector3 curRot = transform.position;
Vector3 look = new Vector3(curRot.x, camRot.y, camRot.z);
transform.LookAt(look);
// allign to local 0
Vector3 rot = transform.localEulerAngles;
rot.y = 0;
transform.localEulerAngles = rot;
I'm not exactly sure why this doesn't work, but it has the same result as Method 1. (Inverted rotation on one side)
Method 3:
Vector3 lookAtPos = camera.position;
Vector3 lookAtPosLocalised = transform.InverseTransformPoint(camera.position);
lookAtPosLocalised.x = 0;
lookAtPos = transform.TransformPoint(lookAtPosLocalised);
transform.LookAt(lookAtPos);
This works perfectly at first, but after a while it becomes "desynced" with the parent rotation. I don't know what triggers it.
Can anyone help?
I think your first answer might be the best. It only requires a signed angle. Resources for this can be found at this link.
Once you have the signed angle you can use
var finalAngle = (angle + 360) % 360;
this makes sure the signed angle (which means - for left, + for right rotation) becomes a 0-360 rotation, instead of -180 to 180.
I tried this:
Vector3 curRot = transform.localEulerAngles;
curRot.y = 90;
curRot.z = 0;
float xDir = AngleSigned(camera.position, transform.position, transform.forward);
curRot.x = (xDir + 360) % 360; ;
transform.localEulerAngles = curRot;
But the rotation is very erratic at certain angles.
Try this, not sure I got your point
Transform other;
float angle = other.localEulerAngles.z;
transform.rotation = Quaternion.Euler(0, (angle+180.0f),0);
