I do not understand, why jointed object can't look at target.
Example: 2 boxes with hinge joint (anchor is at the touching place) and a target object. When I say A-box to lookAt target, I think it will just turn on X-axis. But both of the boxes start to shake. Why?
Take a moment to reflect on what a call to LookAt is trying to do.
It's rotating the transform while ignoring physics.
That's bound to create problems, since you're not rotating the whole system, you're moving one part of it. Your rotation with LookAt is "fighting" with the adjustments the physics system is trying to make.
To solve that conflict you can do one of the following:
Rotate the entire system (both cubes). This will involve putting them all under one transform, and having that transform rotate.
Use a physics-based approach. It won't be too hard, but won't be as simple as a function call. You'll probably need a simple PID controller such as the one outlined in this thread.
Related
I have a simple game done using unreal engine 4,
The turret of the tank should turn toward the player pawn.
I made the blueprints code to build that, but the turret rotates quickly and incorrectly.
Video about problem
I tried to solve the problem many times without any results !!
Hope to help me.
There are probably a few ways you can do this, but you can simplify this quite a bit. I also suspect you can do all of it in the animation blueprint.
Simplify the first part (XDoMa.jpg) using the Find Look At Rotation node.
Break the output of this and create another rotator with the yaw from that node and the pitch and roll from the turret's world rotation (you're currently setting pitch and roll to zero in cDJ08.jpg, which you don't want to do in case the tank is on a slope).
To rotate the turret to point at the target, use the RInterp To node and connect its output rotator to a Set World Rotation node. The nice thing about the 'RInterp To' node is that you can set the speed. For a bit more realism you could use some simple maths to accelerate and decelerate the turret's rotation.
Another thing you'll want is a bool variable in the tank actor BP. Then you can use a branch in the animation BP to trigger the stuff above when you set the bool to true.
The key parts to this are the Find Look At Rotation and RInterp To nodes, and to do all of it in the animation BP.
I've been looking for a solution to this for quite a while now (meaning several days) and I haven't found anything yet. Maybe I'm thinking about it wrong and there isn't a way, but let's try!
I'm recording hand-data on a Hololens (the Unity Hololens Input Simulation for now). This essentially gives me one float AnimationCurve for each hand joint for each transform.position.x to z and rotation.x to w. Now my goal is to put these curves into an AnimationClip and add it to an AnimatorController (via an AnimatorOverrideController) that animates a hand rig and replay the recordings. Everything so far works!
However, the recorded hand-data from the Hololens is in world scale, not in local scale. (which makes sense, since you usually want absolute coordinates when you want to know where the hand is.) But to animate the hand, it seems I'm only able to set local coordinates, which I don't have.
Example:
clip.SetCurve("", typeof(Transform), "localPosition.x", curve.PositionX);
Here, the clip takes the the x-coordinates from some hand joint and puts it to the localPosition.x of the corresponding hand rig joint. The problem: curve.PositionX is world-scale (absolute coordinates), but localPosition.x takes local-scale (coordinates relative to its parent).
I can't simply change "localPosition.x" to "position.x", like so:
clip.SetCurve("", typeof(Transform), "position.x", curve.PositionX);
even though the Transform class has both properties and position is the object's world scale position. I'm not sure why this doesn't work, but it gives me the following error:
Cannot bind generic curve on Transform component, only position, rotation and scale curve are supported.
I'm aware that it doesn't make much sense to use absolute coordinates for an animation, but I simply don't have anything else.
Does anyone have an approach how I can deal with this in a sensible, not-too-cumbersome way? It seems I have all the important parts, I just can't figure out how to put them together. Thanks so much already! :)
From my basic understanding, it seems like you are using the Input animation recording service provided by MRTK. Unfortunately, MRTK does not provide the localPosition version of Curves data. However, you can modify the data from the recordingBuffer after the InputRecordingService stops recording.
So, this is a method worth trying for you: in the handJointCurves dictionary property of recordingBuffer field, a set of pose curves is stored for each joint. And then, base on this table:Joint pose curves, subtract the position value of the key None from the position value of each other joint in every key frame so that the localPosition based on the key None is obtained.
I am making a simulation of some fish in a lake.
I am using rigid body as otherwise they move through the sides. But when they hit into the sides they rotate and then the script I have to set their rotation to 0,0,0 when they leave fails.
Your problem may be occurred by the fact that you are using unity's physics to move the fish but trying to set rotation directly. In this case movement and rotation of the fish are driven by Physics and forces, applied to the object. But you still can affect rotation and position if you reset all forces. Try looking here to learn how to remove forces.
Also when dealing with Physics in Unity, don't mess Update() and FixedUpdate() methods, because it may lead to an incorrect result.
When you say "hit into the sides" do you mean the sides of the simulated lake?
If so, one option might be to set the objects that denote the sides as "kinematic." Then you can detect when a GameObject (such as a fish) collides with it but it won't cause any physics reaction.
(ref: RigidBody)
I'm fairly new to Box2D and trying to figure out the best way to make a unicycle. The unicycle essentially is in two pieces, the wheel and the stem (with seat post etc). I've tried attaching the two with a revolute joint and using a motor for the wheel, which works well except that the stem is then subject to forces from the movement of the wheel. I want to be able to directly control the rotation of the stem (via the accelerometer on the iPhone), and have it unaffected by the movement of the wheel, except to maintain its position based on the position of the wheel.
What is the best way to do this? How do you control rotation of b2Body's? Should I be using a distance joint instead? Any help would be appreciated.
I see several routes, depending on your needs. Which way is preferable is up to you and your game.
1. Fix the stem's rotation
For the bodyDef for the stem set the fixedRotation-flag to true. This prevents any rotation of the stem (be it by forces from the motor joint, (de)acceleration or collisions.
Than you'd have to manually set the rotation each tick. This is easy if it's purely based on the iPhone's position. If you still want to calculate other factors into it, things might get from a bit more complicated (e.g. adding rotation if stem leans too far in one direction) to somewhat painful (have collisions affect the rotation).
2. Constantly apply balancing forces to the stem
Each tick read the stems angular velocity and apply countering forces to balance the stem.
While this would probably be more complicated to implement correctly (always find the right force to apply etc.) it may result in a more realistic behaviour as the fixed rotation obviously removes most reactions stem movement would have and how the stem itself is affected by the world.
3. Don't actually use a wheel
While your layout is the obvious choice for a unicycle (and seems to be a somewhat popular choice for all kind of characters) it might not be the best choice from a gameplay point of view.
Instead you could combine the stem and wheel fixtures in a single body (or attach them with a prismatic joint) and create all movement by applying forces to this body. A sensor at the bottom can inform you of ground contact to determine if movement forces are to be applied.
This way you'd get rid of all the forces a wheel creates (forces to the stem may not be the only unwelcome ones in gameplay) and still have it react to all external forces.
I am making a paper toss kind of game in Unity3d. I am implementing wind effect using constant force. I wanted to know how to make object fall in line with the target ie, if the object gets over the target, it should go in or fall in line with the target, not go behind or in front of the target. At present when I swipe applying a constant force, for different angles of swipe the distance moved by the object differs. Help would be much appreciated.
In FixedUpdate, use Physics.Raycast to check to see if the object is over the target. If so, set the x and z values of rigidbody.velocity to be zero (assuming y is the up/down axis in your game world) and disable the ConstantForce component (i.e. gameObject.GetComponent<ConstantForce>().enabled = false). Note that this won't be most realistic of movements, as it will seem like the object suddenly moves straight down when it goes over the target -- but it sounds like that's what you want.