How to Make Physics-Based Hands in Unity XR
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- Äas pĆidĂĄn 2. 07. 2024
- The most critical but HARDEST part of VR is getting the hands right. If you miss the mark here, you might as well make an FPS game...
Hey, devs! We're continuing our series on how to make a VR game, and this week we're talking about physics-based hands! That's right! No more phasing through walls and picking up objects from the middle. Take your game to the next level with these tricks!
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â Timestamps
0:00 Subscribe!
0:37 Settings & Setup
1:39 Add Colliders
5:24 Add Rigidbody
6:06 Add Direct Interactor
7:22 Code!
10:43 Position Tracking Test
11:51 MORE Code!
13:51 Position + Rotation Test
14:06 Adding Offsets
15:51 One more major issue...
16:33 Like!
17:04 Outro
For anyone who has issues with hands randomly flipping 180 degrees or flipping when turning the hand(Over-turning), this is the fix for the script(Adds checks for rotation):
private void PhysicsMove()
{
// Position
var positionWithOffset = _followTarget.TransformPoint(positionOffset);
var distance = Vector3.Distance(positionWithOffset, transform.position);
_body.velocity = (positionWithOffset - transform.position).normalized * (followSpeed * distance);
// Rotation
var rotationWithOffset = _followTarget.rotation * Quaternion.Euler(rotationOffset);
var q = rotationWithOffset * Quaternion.Inverse(_body.rotation);
q.ToAngleAxis(out float angle, out Vector3 axis);
if (Mathf.Abs(axis.magnitude) != Mathf.Infinity)
{
if (angle > 180.0f) { angle -= 360.0f; }
_body.angularVelocity = axis * (angle * Mathf.Deg2Rad * rotateSpeed);
}
}
Thanks!
Life saver, thank you so much
Good samaritan
I was looking for that for smth like 2 days!
I love u dude!
I mean, not fr
But if u don't have boyfriend/girlfriend then u know...
Bro, thank you for all these videos, I've been working with Unity for 4 years now, and recently got a Quest 2 and wanted to start developing for VR, your videos are super helpfull.
Thanks again!
You're very welcome!
i hope you upload that next video, i really need to know how to not make my hands just phase through objects. AWESOME VIDEOS bro keep up the work
Soon!!
Will look forward to part 2!
Still waiting đđđ
I fixed the hands a little, I added a time.deltatime to body.velocity = (positionWithOffset - transform.position).normalized * followSpeed * distance * Time.deltaTime; and body.angularVelocity = angle * axis * Mathf.Deg2Rad * rotateSpeed * Time.deltaTime; . that made the hands more stable, but the hands were moving too slow so I changed Follow speed to 1800 and rotate speed to 6000. You also should move the player inside XR rig so if you walk around the hands are more stable.
Thanks!
I tried doing that but it is still really slow
instead of:
body.velocity = (positionWithOffset - transform.position).normalized* followSpeed * distance * Time.deltaTime
try:
body.velocity = (positionWithOffset - transform.position) / Time.fixedTime
this should give the velocity needed to get to the target in one frame...
Great content man, thanks!
sure thing!! appreciate ya
Awesome bro! i use my own 3d hand models and it works just fine! i had one little issue in the other tutorial on how to animate the hands. i did everything but it just didn't work for some reason. but i fixed it i just watched an other tutorial and then i came back to this tutorial. im exited for the hand pose tutorial for when you grab objects! see ya soon
Glad you got it working! Yea some of the most recent updates have broken the hand tracking a bit. Hard to keep up with all the changes Unity makes đ
Looking forward to the next part, great stuff!
Thanks!!
I'm in the works of learning VR game design using all of your tutorials and loving them!! Having a slit issue with floats converting the vector3 with this exact code. Would you have any idea on how to get around this issue?
Great to hear! Join the discord if you're still having issues and we can help you troubleshoot!
Hi Justin, thanks for the detailed Video. I'm using oculus integration sdk and in my ovrhands, i have attached colliders and the tracking works really well. However, I am unable to manage grab and other interactions like earlier.
Hi there, great video! Everything works fine except for one small thing: when the hands collide with a box collider they take a lot of time to return the right position (the follow target one) any idea to solve this?
Great tutorials :)
Thanks!
What video/tutorial do you want to see next?! Reply to this comment and let me know! đ
After the hand videos, would love to see a physics body!! Or a full-body sorta rig at some point!
@@thebutterappletutorials6553 absolutely!! you got it!
@@JustinPBarnett Yesss!!!
I know it's not really related to this video but I'd love a video about how to properly make tools (like weapons or actual tools) in VR which you can pick up and then use all the inputs from the controller that's holding it to activate something. I know that you can easily do that with the activate-function, but that's only for the trigger and I'd also want to use the A and B Button or the stick.
Anyways great video!
Good idea!! I'm definitely going to do a VR gun video in the future! probably after all these hand tutorials
I can't seem to find the additional videos for physics hands
I had a trouble when I tried to attach the hands to the controllers,. It was solved when I replace the Update() function with FixedUpdate() function. BTW, Thanks for the great videos with super high quality!!
i have looked for tutorial like this for sooooooo long. you have saved me! thanks a lot
You're welcome!
10:44 what's the point of calculating the vector between the position of the gameobject (transform.position) and the position of the target in line 58, and then normalizing it if it's to remultiply it by its distance behind that we calculated in line 57. Because then we find the non-normalized vector if we multiply it by its distance
Really need a part 2
The most requested video by far đ
Haven't watched all your videos yet. Has the second part of this come out?
Not yet!
No clue, if people are having issues with this, but the adding the absolute offset didn't quite match the correct position for me. The position only matched at a specific controller position and rotation.
So to calculate the correct target position, I used "Vector3 targetPos = _followTarget.TransformPoint(positionOffset)" , where positionOffset is the local offset to the hands from the controller.
TransformPoint calculates the world position from a local position.
Love the tutorials! I'm having one slight issue though and I'm not sure if I did something wrong. The rotation seems to be too slow and if I turn my hand relatively fast its very obvious that the rotation is slow. I have all the same variable values but the hand still seems to rotate too slow. If I turn up the rotation speed I get the vibrating that you talked about. Thank you!
Set the rigidbody.maxAngularVelocity = float.PositiveInifinity;
@@JustinPBarnett Awesome thank you!
Hey Justin, how would you combine this with ik
Thanks for the tutorials. They help a lot! I am having an issue where the hands are not rotated properly to match the controller rotation, EVEN if I rotate them or the controllers in the editor. Can you help me with this? Thanks!
You're welcome! Are you making sure to adjust the offsets and not the actual hands?
Thank you! It worked
hey how do i stop hands going thought walls
Hey man are you ever going to make procedurally animated hand tutorial?
Yes!
I have no idea if I'll get a response, but I got an issue that came from this. I followed all the tutorials about getting the hands to be rotated correctly. After adding the physics, the hands will not rotate correctly, regardless of what I do in the inspector. Any help would be appreciated, the code is almost identical to this video outside of some minor changes. Plus the code for the physics grab.
Could this be used to interact with other humanoid models? For example if you had a human model with a rig (from blender) and an animation where said human tried to punch you, could you effectively grab its arm as if you were fighting against it to stop it punching you?
Yes!
Is this still nessacry relevant to your 2022 video where the hands are children of the controllers
I'm running into a lot of issues after following that video and then onto this one
do i need the follow and rotation if they just stay as children under the controller
The distance is calculated between the followObject and the transform.position. But the relative ration is calculated between the followObject and the _body. Shouldnât these two be consistent in using the same pair?
Yea good catch! I fixed this in my Inverse Kinematics video
How to get the velocity of Left and Right from controller movement ? Action mapping gives zero every time, except one but it's velocity tracking from either controller.
You can join the discord for some help if you need any!
Great video. So, second part :P?
It's coming!!
my hands are jittering alot can you help me with this
For some reason when I click in the hierarchy to go to prefabs and unpack the XR Rig. Prefabs does not show up. Itâs very strange, I donât know what Iâm doing wrong or what the issue is. These tutorials are awesome though! Keep up the good work!
You can only unpack prefabs, so if it's not blue you won't see a prefabs option
Did the second video come out about objects in your hands?
Not yet đŹ
At first, thanks for your tutorials. I animated the hands with your older video and tried to implement the physics from this video. The physics work for the most part but the animation is gone. How can i add the animation again?
Well I removed all the animation code in this video. You could just keep those in
@@JustinPBarnett Well I did. I did not delete anything from before. But the animation is gone anyways.
@@schaki05 you mean the animation file is gone?
@@JustinPBarnett The files are still there. The Animation ist just not happening when I pres the buttons. I just implemented everything from this video after i completed the animated hands videos and did not delete anything.
@@JustinPBarnett found it now. The Speed was set to 0 somehow. Went through everything to find it. But thanks anyway. Now i have to solve my problem with the IK. My Camera is stuck to the ground somehow :)
video worked great! but i do have some bugs i was hoping you could help with,
im using a locomotion system which does continuous moving and turning, but if i try and move forward my hand gets in the way, meaning i either have to stretch my arm out so i can move forwards or just live with the fact i cant move forwards, also my hands sometimes collides with my own body from the xr rig, meaning it launches me out of the map, i also had this problem with my grab-able, which is a sphere, any help?
also, side problem, my animations arnt running anymore, cant figure out why, seeing as the animator still has the controller and avatar set
@@ollyfry3560 make sure animation speed is more than 0 and youre second problemn edit project setting physics scroll to the bottom and uncheck youre body layer or make a body layer for youre xr rig and hands and grabable layer and unmark layer collosion and it will be fixed also sorry for bad english
Join the discord if you're still having issues and we can help you troubleshoot!
If you feel like your hands are rotating too slowly, remember to set the "rigidBody.MaxAngularVelocity" to a higher number. i believe default is 7.
hi will coilder stop them going thought objects walls without the other code
Yes, but the code is to keep the collider aligned on the player.
for curiosity, would it still work if i just added the collisions but , keeping the normal Xr control of the hands ?
You'd get some weird physics effects because the hands will be teleported to where your controller is every frame instead of moving there by physics, so eventually you'd have your hands teleport inside of something when you tried to interact with it and that'd cause things to fly off sporadically
@@JustinPBarnett thank you :D
@@_Garm_ sure thing! it's fun to try and see everything shoot off in different directions lol
@@JustinPBarnett haha could be game idea just there ,the "Hot potato game" :P
hahaha for real
how did you do it can you share with me , thank you
That's a vauge question
I've just followed this tutorial but now my hands don't animate or pick up objects from the last tutorial :( What have I done!? Also love the tutorials thank you for helping me learn!
Join the discord and we can help you troubleshoot!
You have to change the Animation Speed on the Hand script because you change the float from speed to AnimationSpeed so it defaults to 0.
Just tried this out, one issue I've run into is that when I'm rotating my left hand when it hits a certain degrees it rotates the opposite direction till it reaches where I was, any fix for that?
Yea there's a pretty easy fix for that! After the .ToAngleAxis() method do a check to see if the angle in degrees is greater than 180. If so, then subtract 360 from that number. This will always give you a range between -180 and 180 and should fix any weird over-rotation.
@@JustinPBarnett Works like a charm thank you!
@@thebutterappletutorials6553 perfect!!
@@JustinPBarnett Hey Justin, I'm having the same over-rotation issue. Could you please tell me how to check the angle in degrees? I'm looking at the .ToAngleAxis method in my script, but I don't see any area where it shows angle in degrees or how to calculate it. I've been searching for a solution. Thanks!
â@@sillyoldbear5379 Had the same problem and implemented his solution. The .ToAngleAxis function has that part "out float angle" - that variable "angle" is being set by the function, and is the difference in the angles of the two objects. If the value of it is greater than 180, you want to subtract 360 from it so that it stays within -180 to 180. So the code becomes:
q.ToAngleAxis(out float angle, out Vector3 axis);
if(angle > 180.0f) { angle -= 360.0f; }
_body.angularVelocity = axis * (angle * Mathf.Deg2Rad * rotateSpeed);
It just adds one extra step between the two lines. I'm certainly not an expert, but that is what worked for me!
anyone willing to discord and help me on screenshare, i have nearly it just struggle with the animation. is there no way to just import it :(
Yea ask around on the discord!
Why not have each hand just have a mesh collider so you don't have to do each part of the hand?
You can try it that way! I havenât given it a shot so donât know if it would work when the hand animates. Let me know what you find out! Iâm curious cause thatâd be much easier
why you just don`t use XR Direct Interactor for Physics?)
Because it's not physics based
Is there a way to like skip over the animation part?
You mean like comment it out?
@@JustinPBarnett i think he means just add colliders so you can interact, no animations, i also need something like this because my hands are just cubes i just need them to collide and pick up
anyone else having issues not being able to move after this tutorial? the hands move, but only about .01 units before stopping. any help?
I didn't have the same issue, but a similar issue, go back and look at his hand script and make sure yours is 100% exactly like his at the last portion of when he shows his final code. There's a part where he replaces a variable, I missed it on one thing and was having minor bugs as well
đ
Instead of moving with the controller positions, my hands just fly away. Any solution to this?
Try teleporting them to the controllers' positions on start. You may be starting out touching another collider and that causes the flying away thing
@@JustinPBarnett I will try that, thank you
Did you manage to find a solution, I've the same problem
@@Tu-madre6969 I never was able to solve it, no
@@rylandwilson739 ok
just commenting for the algo. Thanks, m8!
Thanks so much!
I have problem,my hands are shaking a little everytime
Check out the video coming out today about gorilla tag movement. It should help clear some stuff up.
I tried making these hands, and the hands are far away from the actual controllers, and the hands float up and down slowly like 0 gravity, and sometimes they collide they start flying everywhere, but the controlling of the hand kinda works
Edit: Fixed it.
How did you fix this issue?
Hey, there's a good chance you will not have time to read this but If you do, I would like to see a tutorial on stabbing in vr. I 100% understand If you won't be able to do one.
I'll add it to my queue!
Download the Project (for FREE): www.vrcreators.io/codedownloads
the most important part of any vr game is to have a Rigidbody controller with NO Translate, No Transform, only AddForce or .Velocity.
Agreed for any physics-based game!