I encountered another issue with hand-object interaction using a Leap Motion device. In particular, I use the LM to perform orientation manipulations on virtual objects.
I want to use the difference between the current and last orientation of the hand to manipulate the object:
Quaternion relativeOrientationHands = Quaternion.Inverse(currentHandOrientation) * updatedHand;
transform.rotation = transform.rotation * relativeOrientationHands;
It works fine, however the problem is that, let's say I rotate the object 180 degrees around the x axis (after that, y is pointing downwards). If I release the object afterwards, and grasp it again, the orientation changes get from then on applied to the new orientation of the object which is super confusing to use. (Original: turn hand to the left - object turns counter-clockwise; After: turn hand to the left - object turns clockwise)
Unfortunately, I don't know the math to fix it, but maybe someone can help me out. How can I apply the orientation changes of the hand to my virtual object, with respect to the default object orientation using Quaternions. Maybe, something with normal vectors?
EDIT:
The 3 figures illustrate my problem. The first figure shows the object in its original orientation (x-right, y-upwards). I turn the cube 180 degrees by rotating my hand 180 degrees clockwise around z (blue axis), after I release it, x is pointing to the left and y is pointing downwards (figure 2). If I grasp the object (figure 3) in its current orientation, and let's say I would want to perform a 90 degrees clockwise rotation around the y-axis. In figure one, I could do that by moving my hand 90 degrees clockwise. However, I changed the orientation of the cube with my previous manipulation. Therefore, I would have to perform a 90 degrees counter-clockwise rotation with my hand to move the object in clockwise direction, because the y-axis is flipped (figure 2-3). I always want that turning your hand 90 degrees clockwise results in a 90 degrees clockwise rotation of the object regardless of its current orientation.
Thank you very much
Best
R.Devel
Related
I have a Cube in Unity. I'm moving and rotating the cube and I want to track the rotation around a special axis.
The Application is a Holo Lens 2 Application and I'm grabbing an Object with my hand. I then want to rotate the Object in my Hand around one of its local axis. I need that rotation around that axis, meaning a float, to rotate another object around its oft local axis by the same amount.
Any Idea how to achive this?
I'm new to 3D design, so this might be a silly question.
I have trouble simulating wheel camber using rotation with Quaternion.
What I understand is that the rotation of the WheelCollider occurs along the X axis, whereas in my case the "visual wheel" is rotated 80 ° along the Z axis so the rotation occurs along the Y axis.
This code works well with the FL wheel because its axis is aligned with the collider axis, while it doesn't work with the FR wheel.
collider.GetWorldPose(out Vector3 position, out Quaternion rotation);
visual.transform.position = position;
// initialVisualRotation is the wuaternion rotation of the visual at Startup
// in this case: X=0 Y=0 Z=80
visual.transform.rotation = initialVisualRotation * rotation;
These are my local and global rotation axes for the right front wheel (FR).
How can I "adjust" the wheel rotation without change initial axes (as I did for the FL wheel)?
Are there some quaternion operations to adopt in these cases?
A bit of workaround for not having to deal with messed up transforms is to make object a child of another empty object.This way you can make parent object rotated to make wheel tilted but Child( actual wheel) will have its original axis always not messed with and so you can use simple script to always rotate it around same axis that is always going to be the same despite whole system(hierarchy of objects) being " tilted".
Parent is responsible on rotating around one axis and child around another.
I think you need to take a step back and arrange your prefabs this way as it seesm you did not.
Goal:
Calculate a rotation, that can be used, to correct the Transform of the bones, so they get rotated as expected when manually rotated.
In Detial:
Character's bone Transform is not imported to Unity correctily, ie. the left hand's Z axis does not looks towards the top of the hand, but backwards, while the right hand's Z axis looks forward.
The bones default rotation is not the same as you would expect if you have seen the rig in another application before.
I had the idea to create a class, that puts the character in T-Pose, then maps the bones rotation.
(I would assume that Unity does something similiar under the hood, that's how I got the idea.)
So the class would be used with an API like this:
/// This should return the rotation, where the bone pointing forward rotated by rotation.
/// Ie. when rotation = Quaternion.Identity the left hand should look forward.
Quaternion CorrectRotation(HumanBodyBones bone, Quaternion rotation)
{
return Quaternion.Inverse(tPoseRotations[bone]) * rotation;
}
The problem is, that I can't seem to find a good way to map theese rotations.
My last attempt was this:
Vector3 boneDirection = (boneTransform.position - parentTransform.position).normalized;
Quaternion mappedRotation = Quaternion.LookRotation(boneDirection, parentTransform.up);
As you can see in this image, with this method the hands look in the same direction, forward, but still not rotated correctly, they have an offset from the desired result. (The correct rotation is shown by the purple hands.)
When given other rotations, the hands follow with the same offset, so other then this unwanted offset they work correctly.
So basically, I would appriciate any help to fix my problem, either this way, or with a different solution, that works with different rigs.
I have a UIImageView that is set to move up and down the screen with the value of the accelerometer, using the following code:
ship.center = CGPointMake(ship.center.x, ship.center.y+shipPosition.y);
Where shipPosition is a CGPoint set in the accelerometerDidAccelerate method using:
shipPosition.y = acceleration.x*60;
Obviously this works fine, it is very simple. I run into trouble when I try to something equally simple, vary the rotation of the image depending on its acceleration. I do this using:
ship.transform = CGAffineTransformMakeRotation(shipPosition.y);
For some reason this causes a very strange thing to happen, in that the image snaps back to its origin every time the main method is called. I can see frames where the image moves to where it should be, but then instantly snaps back.
This problem only happens when I have the rotation line in, commented out it works fine. I have no idea what is going on here, I have done this many times for different apps and i never had such a problem. In fact I copied my code from a different app I created where it works fine.
EDIT:
What really confuses me is when I change the angle of the rotation from the acceleration to the position of the ship using:
ship.transform = CGAffineTransformMakeRotation(ship.center.y/10);
When I do this, the ship actually rotates based on the accelerometer but does not move, which is crazy because a changing ship.center.y means the position of the ship is changing, but it's not!!
You should set the transform of you view back to CGAffineTransformIdentity before you set his center coordinates or frame and after that apply the new transformation.
The frame property returns the transformed coordinates of a view if it is transformed and not the true (well actually the transformed are true) coordinates.
Quote from the docs:
Warning: If the transform property is not the identity transform, the value of this property is undefined and therefore should be ignored.
Update/Actual Answer:
Well the actual problem is
shipPosition.y = acceleration.x*60;
Since you set the y pos in accelerometerDidAccelerate.
The acceleration won't remember it's old value. So if you move your device it will get a peak and as you slow down it will decelerate again.
Your ship will be +/-60 at the highest acceleration speed but will be 0 when you stop moving your device and shipPosition.y will be 0.
CGAffineTransformMakeRotation expects angle in radians, not in degrees.
1 radian = M_PI / 180.0 degrees
I'm using Core Motion and would like to count rotations, so if i place the iphone on the table and start to rotate it clockwise and do 360 degrees, i would get 1 rotation.
What should i use from Core Motion, yaw, roll, pitch, gravity, rotationMatrix or ?
Please help me.
Cheers.
You'd want to watch yaw — that's rotation around a notional line that would come straight upwards, out of the screen. It actually goes from +180 to -180, but for your purposes if you're rotating clockwise, screen upward, then you can just watch for the number to get higher instead of lower — that'll detect when the value goes beyond -180 and reappears somewhere below +180. Alternatively, look for any absolute change in value greater than, say, 180, if you want to be able to detect rotations clockwise or anticlockwise.