Develop Reference

Pinch and rotate around a point using MRTK and Hololens 1

I'm trying to rotate a beam/cuboid around a pivot using MRTK, Unity, and the Hololens 1 when you're doing the pinch and hold gesture. The beam should remain in place once you've let go of the pinch.
My initial thoughts were to get the cartesian coordinates of the pinch and based on their position relative to the pivot, have the beam rotate by however many degrees needed. E.g. the hand position while pinching is (1,1,0), and the pivot position is (0,0,0). Thus, the beam should be rotated at 45 deg in the XY plane (we ignore the z components). I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2. (https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/Input/HandTracking.html#hand-tracking-events & https://microsoft.github.io/MixedRealityToolkit-Unity/api/Microsoft.MixedReality.Toolkit.Input.IMixedRealityHand.html#Microsoft_MixedReality_Toolkit_Input_IMixedRealityHand_TryGetJoint_).
Does anyone know how to go about doing this or at least point me in the right direction (tutorials/code/assets would be much appreciated!)
Thank you!

I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2
Yes, HoloLens1 does not support hand tracking, such as touching holograms directly with your hands or pointing and committing with hands. It is recommended that you try to use the interaction model Gaze and commit, so that you can easily get the position of GGVPointer.

Pinch to rotate interaction can be achieved by adding the ManipulationHandler component from MRTK to your cube. The component can be configured to allow two hand manipulation like this.
I'm not sure how to go about doing this as the documentation seems to indicate that the only way to get the coordinates of the hand/pinch only works for the Hololens 2.
There are a few ways to query pointer position. The code below should return the Right GGVPointer position for the hololens.
Vector3 pos;
GGVPointer pointer = PointerUtils.GetPointer<GGVPointer>(Handedness.Right);
if(pointer != null)
{
pos = pointer.Position;
}

In case you just want to rotate the Object around its center,you can use the Boundingbox Component. It creates handles that can be pinched and moved to rotate an object. you can disable the axis you don't want. It works even on the HoloLens 1.

Objects having same distance/radius from the center (camera) in Unity 3D

It's a 360 Video application on Unity 3D.
I want to place several objects around the camera (which has a fixed position), but I need this objects to have the same distance (same radius) from the Camera (which is the center). How can I do this? Either on Editor or by code.
I have been manually displacing objects around the camera, by dragging them by arrow tool. But it's as inaccurate as a pain to do. :)
Any light on this would help me a lot! Not only me, but anyone working with 360 videos in Unity.
Thank you all in advance!

To solve your problem, an easy solution would be to add a child "child_of_camera" to your camera and then add a child "child_of_child" to the "child_of_camera".
Now that you've done this, move the "child_of_child" away to however far from the camera you'd like it to be. After this, apply the random rotation you'd like to "child_of_camera".
Duplicate "child_of_camera" to however many objects you'd like on screen and then rotate them all to your preference.
Now, when you're moving around the camera, these children will follow along with the camera.
If you're looking so that the rotation of the camera doesn't affect the objects there are two ways you can handle this:
Place camera and "child_of_camera" (this name would now be misleading and should be renamed) under an empty GameObject and move "empty_GO" on the X,Y,Z axis instead of the camera.
or
Create a quick script to attach onto "child_of_camera" so that it always sets the "child_of_camera"s world space rotation to Vector3.zero.
As I stated in the comments, this solution is most likely not the optimal way to fix your problem but it is definitely a very simple solution that is easy to understand and implement. I hope it helps.

How can I find the rotation of the head in Google Cardboard Unity3D?

Hey guys how do I find the rotation of the phone with Google Cardboard SDK in Unity3D, like the way the persons head is facing? I need to find if it is facing more towards the east, the west, or the north. Do I find the rotation of the head, or the parent Main camera?

The Cardboard class contains a property called HeadRotation which is a Quaternion.
Quaternion crtRot = youCardboardController.HeadRotation;
To use its rotation like you'd in Unity with directional vectors you may simply multiply it by Vector3.forward.
Vector3 lookDir = crtRot * Vector3.forward;
Visualizing the vector in editor might help narrow down issues
void Update () {
// ..
Debug.DrawRay( pos, lookDir * 100, Color.blue );
// ..
}
From here you only need to know where North is, in meaning of the facing vector. Do a Vector3.Angle() and you have the angle between your avatar's and North's vector. You might want to evaluate both vectors with their y axes set to 0.
You could also use Vector3.Dot() (the dot product) to determine how much both vectors look into the same direction.
I had an issue with HeadPosition, which wasn't updated properly. So if you operate from HeadPosition keep in mind it may stick to 0,0,0 .

Take Head.transform.rotation - that's the orientation of the user's head.
I'm not really sure what do you mean by North or West. If the mobile device has a magnetometer, then maybe you could read it's data to determine where North is, but I've never done that

It would be the rotation of the Head object, although the Main Camera usually has the same rotation.
But if you want the direction relative to the real world, that information is not available in the SDK. The compass cannot be used because of the magnet, so there is no way to get the real direction.

Just take the rotation angle of the main camera in the scene. It will gives you the head rotation angles with respect to x, y and z axis.
In GVR based VR scenes the system is internally rotating the camera with respect to our head movements. So it's easy to get the head rotation using main camera rotation angles.
For that,
//local rotation of the Transform of the camera
Camera.main.transform.localEulerAngles.y
//The world Y rotation
Camera.main.transform.rotation.y

Rotate an object according to a plane normal

I am making a FPS game, I created a peaceful AI for the moment and when the character is died, I just want it to be oriented according to the normal below it. I show you the result for the moment :
as you can see, the character is flying, because the terrain is not straight.
I am trying (without success) to make something like that :
I have the (x,y,z) coordinates (character position) and the normal to the plane.

Yes the normal is always facing up, as you can see on my drawing, even if I drew it in the good pose. I dont understand when you are talking about the quaternion, which new normal are you talking about ?
I already have the normal of the plane under the character, so, part of the jobs is already done :)

Your character's death pose is always with the normal facing up, right?
And you want to rotate it to another normal.
You can find a Quaternion that represents the rotation between two vectors (up and the new normal) to rotate the mesh.
This question has the answer to that:
Quaternion from two vector pairs
To know the normal of your terrain, you can probably cast a ray down and get the normal from the collision information depending on the physics engine you are using.
Edit:
Some background info:
A quaternion represents a rotation. So what I'm suggesting is that you use the answer from the question I linked to calculate the rotation between the default orientation of the character's death pose (UP) to the new orientation (Terrain Normal)
Then you can just transform your dead character with the Quaternion and it'll follow the terrain's normal.
Here's a sketch: calculate Q from UP and N with the solution from the Link and rotate your character's model with Q:

Casting a ray from mouse through distortion matrix

I've searched the board, as well as the oculus board, and unity board. Couldn't really find something that helped.
I'm working on a vehicle simulation. Before we started using the oculus, it was just a regular first person perspective. You used a racing wheel/pedals to drive and the mouse to control all the buttons and switches etc. We use raycasting from the mouse point on the screen into the world to interact with the various controls in the vehicle.
Now that we're using the oculus, the raycast isn't taking into account the distortion matrix used on the oculus cameras. So you're not actually casting a ray at what you're visually clicking on. Using Debug.DrawRay I found that it was slightly off. Just to be sure, I disabled the lens correction via inspector on the OVRCameraController and sure enough the raycasting was working again.
The ray itself is calculated the usual way one does when firing from the mouse point:
ScreenPointToRay(Input.mousePosition);
Would anyone have any idea how I can adjust my ray so it works with lens correction on?
Cheers,
Gordon

Simply multiply the Distortion-Matrix with the Ray's Vectors (Position and Normal) and you have your new Ray. I would suggest using Homogeneous Coordinates with 4x4 Matrix and Vec4's where Positions has component w = 1.0 and Normals have w = 0.0; This way you can simply multiply and you are done - depending on lookup direction you might have to use the inverse matrix :)

Alright, what I ended up doing was creating a 3D cursor, bypassing the distortion matrix entirely.
I placed a gameobject at the same place as the "head" (between left eye and right eye cameras). It has a script on it that rotates up/down/left/right based on mouse movement. I then temporarily put a spot light with a narrow cone and high intensity on it so it looked like a laser pointer. I figured if the light is hitting things, so should a raycast of the same origin. Which ended up working.
However this didn't really solve the issue of using a cursor. I tried a number of things that ultimately didn't work (didn't line up with with where the light/raycast hit).
Finally I realized I was overlooking something very simple. I lowered the near clipping plane of the cameras and placed a plane as close as I could to the camera while still being visible. I then rotated it on local y by 180 so it would be invisible to the cameras and not block ray casts.
I then added some code so that when a raycast hit something, it would fire a second raycast from the hit point back to the origin. On the way it would have to hit the plane, which was essentially at the near clipping plane. I would then move my 3D cursor to that hit point.
Now it works as intended. Where the cursor is, is where the original raycast hit. The cursor now matched the position of the laser dot. So then I removed the light component. Done.
Hope this helps someone else someday.