Develop Reference

How to simulate running on Wall like The Flash in unity

Please is it possible to make a Player with rigidbody or character controller run on wall just like The Flash. Please guide me on how to implement this.Here's a link of what I'm talking about. Thank you in advance.

Rotate the player to be vertical to the building, adjust the gravity parameter on your rigid body (make it lower so the added force won't be canceled by it) and just add the force (or set the velocity, whatever makes you happy)

I'm going to assume you already know how to move the player around on the ground. All you need to do is create some form of detection for when they want to begin running on the wall (maybe the player presses a button, or walks up to the wall), at which point you will want to do 2 things: rotate the player to have their feet on the wall, and change gravity to be pulling the player into the wall.
If we assume the player is facing the wall when they go up on it, you can just rotate 90 degrees backwards. Changing gravity should be easy too. Once the player is fully rotated, do something like this
Vector3 newGravityVector = tranform.down.normalized
Physics.gravity = transform.down.normalized * 9.8 //9.8 is the default gravitaty value, feel free to use a different multiplier if you wish.
(this script should be attached to your player)

How can i make a rigidbody speed up everytime it collides with a wall at an angle?

I am trying to make a game where i got a ball with an arrow rotating around it. The ball starts as immovable, but when i hit a button i launch it to the direction the arrow is pointing at. Player will have the option mid air to press another button to make the ball "sticky" so when it hits a wall it will stick to the surface and repeat the process till he gets to the top of the level.
Aside from that, i want to give the option to the player to not stick to the wall if he doesn't press that button and instead bounce off the wall but when he does that, the player should speed up with every bounce, giving the option to either play it safe and slow or try to go fast getting more points as he does.
For the early prototyping i used force to move the player up every time he launches but i am not sure how i can make him speed up every time he bounces off the wall. It feels to me like a math problem more than it is a coding challenge. What i am thinking is that i have to find the angle on which player hits the wall, and add force according to that towards the direction he is supposed to follow after the collision.
Sadly i am not that good with trigonometry (working on it though). I am thinking that i might need to use a formula containing sin, cos, tan formulas but i m not sure how to do it. Any help is much appriciated! If you need more information on it please tell me and i ll be happy to provide.
Edit: After the first reply to this question i also found out those links that dive deeper into the subject. I m gona link them here for people that have the same issue.
Bouncing a ball off a wall with arbitrary angle?
http://www.3dkingdoms.com/weekly/weekly.php?a=2

If your ball has velocity vector V=(vx,vy), then after bouncing from standing surface with normal N, ball's new velocity is
V' = V - 2 * N * (V.dot.N)
where dot is scalar product of vectors (vx*nx+vy*ny)
Particular cases:
bouncing from vertical wall (N=(+-1, 0)) causes reversing of vx-component, vy component remains the same. V' = (-vx, vy)
bouncing from horizontal wall (N=(0, +-1)) causes reversing of vy-component, vx component remains the same. V' = (vx, -vy)
Note I recommend to work in velocity vector components, and use angles only when they are really needed.
If you need to calculate bouncing from moving bat, it is worth to change stationary coordinate system to moving one, connected with the bat, find reflection in that system, and revert to stationary system.

Ok so problem was solved!
I want to thank both #MBo and #shingo for their contribution to the solution. While the answer of Mbo solved the problem via trigonometry and gave me nice material to study and figure out how things work, i followed shingo's advice in the comments of my question and managed to do it without diving deep into math.
So basically what he said, and what i did, was to use Unity's physics engine and let the ball hit the wall. After the ball bounces off the wall, it gets a new Velocity vector towards the direction it would go based on physics. I then created an OnColllisionExit check, and when the ball stops colliding with the wall, i AddForce to it to the direction of its new Velocity Vector3.
Works like a charm!
Thank you all for your contributions!

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.

how do I make object face player?

I've been following various StackOverflow answers, and I think I found code that works, but before I put any code, I've got to figure out whether or not how Unity knows which way is the "front" of the object.
transform.LookAt(target);
I'm trying to use above code for enemy object to face the player. When I place object into the scene, how do I let Unity know which way is the front of the object? (i.e. I place airplane object into the scene. "I" know which way is the front, but does "Unity" know which way is the front?)
Thank you for your help in advance.

From https://docs.unity3d.com/ScriptReference/Transform.LookAt.html
Rotates the transform so the forward vector points at /target/'s current position.
From https://docs.unity3d.com/ScriptReference/Vector3-forward.html
Shorthand for writing Vector3(0, 0, 1).
Front is same as forward vector and forward vector is pointing at object Z axis.

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.