I've been using the transform property for movement so far and that left my Physics a little choppy on collision. To counter this I switched movement using Rigidbody.velocity. This is a sample of my code.
//Start
rb = GetComponent<RigidBody>();
jumpForce = 5;
//Update
horizontalInput = Input.GetAxis("HorizontalInput");
Vector3 movement = new Vector3(horizontalInput, 0.0f, 0.0f);
rb.velocity = movement * speed;
this worked when it came to left and right, however when I want to jump I use this function and my character does not move, is there something wrong I'm doing or am I too much of a beginner to understand?
if (Input.GetKeyDown(KeyCode.UpArrow)) {
rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
}
Looks like you're overriding the velocity when you do horizontal movement so the jump velocity has no effect. You should use rb.AddForce() for horizontal movement too.
You have to be careful not to add too much force though. For an example see this answer.
Vector3.up is the same as new Vector3(0f, 1, 0f) and since X and Z axis are 0 => your character will not move when jumping.
You need to save existing X and Z velocity in rb.velocity without any changing them when jumping:
if (Input.GetKeyDown(KeyCode.UpArrow))
{
Vector3 velocity = rb.velocity;
rb.velocity = new Vector3(velocity.x, jumpForce, velocity.z);
}
Since you change velocity instantly - you'll get instant velocity change which is the same as using AddForce with ForceMode.Impulse
Related
I would like to have a Gameobject point to another only on the Local X-axis.
void FixedUpdate()
{
if(started){
Vector3 targetPosition = target.position;
Vector3 direction = Vector3.ProjectOnPlane(targetPosition - transform.position, transform.right);
Quaternion lookRot = Quaternion.LookRotation(direction, transform.right);
transform.rotation = Quaternion.RotateTowards(transform.rotation, lookRot, Time.fixedDeltaTime * 45);
}
On the y-axis it worked with transform.up instead of transform.right, but on the x-axis the Gameobject only rotates permanently around the z-axis.
You could do something like this:
Vector3 beforeRot = transform.eulerAngles;
transform.LookAt(gameObjectToLookAt.transform);
transform.localEulerAngles = new Vector3(transform.localEulerAngles.x, beforeRot.y, beforeRot.z);
This will take a record of the position before looking at the object.
Make it look at the object.
Reset rotation back to its original except the X rotation
I have been experimenting with trying to recreate a 3rd person character controller from a Brackeys tutorial, but using the new input system and rigid body physics.
The rotation works properly, but moving forward or back moves me forward compared to the camera, and moving left or right moves me backward.
The desired effect is changing the input should change my rotation to match the input direction relative to the camera and then move in the direction the player model is facing
Here is where I'm at:
private Vector3 GetMoveInput()
{
return new Vector3(_input.MoveInput.x, 0f, _input.MoveInput.y); //convert input Vector2 into a Vector3
}
private void PlayerMove()
{
if (_playerMoveInput.magnitude > 0.01f){ //only update rotation if player is moving
float targetAngle = Mathf.Atan2(_playerMoveInput.x, _playerMoveInput.z) * Mathf.Rad2Deg + _mainCamera.eulerAngles.y;
float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetAngle, ref turnSmoothVelocity, turnSmoothTime);
transform.rotation = Quaternion.Euler(0f, angle, 0f);
//down here is where the problem lies I believe
_playerMoveInput = new Vector3(_playerMoveInput.x * _movementMultiplier * _rigidBody.mass,
_playerMoveInput.y,
_playerMoveInput.z * _movementMultiplier * _rigidBody.mass);
_rigidBody.AddRelativeForce(_playerMoveInput, ForceMode.Force);
}
}
I have tried setting y and z to 0f, multiplying by transform.forward, setting _playerMoveInput to transform.forward, and Quaternion.Euler(0f, angle, 0f) * transform.forward but no positive results.
i have start a project in unity 3d.I want to make a spaceship that moving forward,but when i pressed the ArrowUp then i want to change its y postion to
( currentpos+ 1.5 ) but i want this smoothly.
this is my code
transform.position += transform.forward * Time.deltaTime * 10f;
if (Input.GetKey (KeyCode.UpArrow))
transform.position = new Vector3 (transform.position.x, 5f,
transform.position.z);
through the above code the Y position of object can b changed but it work so fast and i want to make it smooth.
so please help me.
I think the best solution to your problem is to use Mathf.SmoothDamp.
Example:
private float targetY = 0f;
private float verticalVelocity = 0f;
private const float smoothTime = 1f;
private void Update()
{
transform.position += transform.forward * Time.deltaTime * 10f;
if (Input.GetKey(KeyCode.UpArrow))
{
targetY = 5f;
}
float y = Mathf.SmoothDamp(transform.position.y, targetY, ref verticalVelocity, smoothTime);
transform.position = new Vector3 (transform.position.x, y, transform.position.z);
}
This example will smoothly change the y coordinate to 5 over the course of 1 second (you can change the smoothTime constant for a different time).
Based in your own code the easiest way for you to work it out could be something like this
//this sets the X position
transform.position += transform.forward * Time.deltaTime * 10f;
//if the button is pressed then modify Y
if (Input.GetKey (KeyCode.UpArrow))
transform.position += new Vector3 (0, 5f * Time.deltaTime * y_speed,0);
y_speed could be a public float y_speed = 1.0f in your script so you could modify it from the inspector to get the effect you want to achieve.
Hope it helps!
Assuming your spaceship is a rigidbody, you should take a look at Rigidbody.AddForce
https://docs.unity3d.com/ScriptReference/Rigidbody.AddForce.html
By working with forces, you can get a smooth movement in all directions very easily, and tweak it within the Rigidbody's parameters (like mass) without fiddling in the script again. It's part of the Unity physics model.
If you only want to move in y-direction, input a vector like (0,1,0) but you can also input the Transform.forward vector of your spaceship's Gameobject. That way, it will always move the direction it is facing in.
I've created a simple pendulum in Unity - GameObject with Rigidbody and Hinge Joint components. I've set both drag ang angular drag to 0. With starting position at 90 degrees I'd expect the pendulum to swing back and forth from 90 to -90 degrees. However, that's not the case - the amplitude decays very quickly, but for small angles the pendulum looks like it's never going to stop.
My question is: How should I configure hinge joints in order to achieve full control over physics and forces that resist motion? My goal is to have physics simulation as precise as it's possible, even at the cost of performance.
I've already tried to reduce time intervals for fixed step and increased solver iterations - none of these worked out.
Why do I need it? I'm planning to design a control system for multiple inverted pendulum on a cart. I have a mathematical model of my pendulum implemented in Matlab and I wanted to verify it using a simple model in Unity (because in that case I adjust all parameters, initial conditions etc. and the physics engine is calculating everything for me). If it turns out the physics engine that is backing Unity isn't reliable enough, what other software would you recommend me?
My understanding is that due to the way Unity's physics operates, there can be a loss of kinetic energy over time in this sort of pendulum motion if you only use a hinge joint. Basically, if you want an accurate pendulum simulation, you have to bypass the physics engine and implement it directly.
There is a very good post on the gamedev stackexchange originally posted by MLM about how to implement a more accurate pendulum simulation in Unity, which I have pasted below.
I thought this would be a relatively simple problem to solve but I spent a couple days trying to figure out how the heck to simulate pendulum movement. I didn't want to cheat and just change the x,y position based on sin(theta) and cos(theta) curves. Instead I wanted to deal with the two forces that are applied in real life, Gravity and Tension. The main piece I was missing was centripetal force.
The Pendulum (mathematics) wikipedia page has a great animation(below, on left) explaining the pendulum motion. You can see my result(on right) strikingly similar to that diagram
The "bob" is the swinging object and the "pivot" is the origin/root.
I also found this article and diagram(below) pretty helpful:
Theta equals the angle between the rope and the direction of gravity.
When the bob is on the left or right the tension equals:
The reason the tension force is greater as the bob approaches equilibrium point(middle) is because of centripetal force:
So the overrall tension formula looks like as the bob swings is:
There are two forces in the pendulum system:
Gravity
GravityForce = mass * gravity.magnitude
GravityDirection = gravity.normalized
Tension
TensionForce = (mass * gravity * Cos(theta)) + ((mass * velocityTangent^2)/ropeLength)
TensionDirection = ropeDirection = bob to pivot
Just apply gravity to your object like you would for a normal object and then apply the tension. When you apply the forces, just multiply the force by the direction and deltaTime.
Below is the Pendulum.cs script(also as a GitHub Gist). It works quite well but there is some rounding error drift if you leave it for a while (doesn't return to exactly same position).
The script works in 3D but of course a pendulum only swings in a 2D plane. It also works with gravity in any direction. So for example, if you invert the gravity the pendulum works upside down. Edit->Project Settings->Physics->Gravity
It is very important to have a consistent relatively small deltaTime when updating the pendulum so that you do not bounce around the curve. I am using the technique found in this article, FIX YOUR TIMESTEP! by Glenn Fiedler to accomplish this. Check the Update() function below to see how I implemented it.
Also as a GitHub Gist
using UnityEngine;
using System.Collections;
// Author: Eric Eastwood (ericeastwood.com)
//
// Description:
// Written for this gd.se question: http://gamedev.stackexchange.com/a/75748/16587
// Simulates/Emulates pendulum motion in code
// Works in any 3D direction and with any force/direciton of gravity
//
// Demonstration: https://i.imgur.com/vOQgFMe.gif
//
// Usage: https://i.imgur.com/BM52dbT.png
public class Pendulum : MonoBehaviour {
public GameObject Pivot;
public GameObject Bob;
public float mass = 1f;
float ropeLength = 2f;
Vector3 bobStartingPosition;
bool bobStartingPositionSet = false;
// You could define these in the `PendulumUpdate()` loop
// But we want them in the class scope so we can draw gizmos `OnDrawGizmos()`
private Vector3 gravityDirection;
private Vector3 tensionDirection;
private Vector3 tangentDirection;
private Vector3 pendulumSideDirection;
private float tensionForce = 0f;
private float gravityForce = 0f;
// Keep track of the current velocity
Vector3 currentVelocity = new Vector3();
// We use these to smooth between values in certain framerate situations in the `Update()` loop
Vector3 currentStatePosition;
Vector3 previousStatePosition;
// Use this for initialization
void Start () {
// Set the starting position for later use in the context menu reset methods
this.bobStartingPosition = this.Bob.transform.position;
this.bobStartingPositionSet = true;
this.PendulumInit();
}
float t = 0f;
float dt = 0.01f;
float currentTime = 0f;
float accumulator = 0f;
void Update()
{
/* */
// Fixed deltaTime rendering at any speed with smoothing
// Technique: http://gafferongames.com/game-physics/fix-your-timestep/
float frameTime = Time.time - currentTime;
this.currentTime = Time.time;
this.accumulator += frameTime;
while (this.accumulator >= this.dt)
{
this.previousStatePosition = this.currentStatePosition;
this.currentStatePosition = this.PendulumUpdate(this.currentStatePosition, this.dt);
//integrate(state, this.t, this.dt);
accumulator -= this.dt;
this.t += this.dt;
}
float alpha = this.accumulator/this.dt;
Vector3 newPosition = this.currentStatePosition*alpha + this.previousStatePosition*(1f-alpha);
this.Bob.transform.position = newPosition; //this.currentStatePosition;
/* */
//this.Bob.transform.position = this.PendulumUpdate(this.Bob.transform.position, Time.deltaTime);
}
// Use this to reset forces and go back to the starting position
[ContextMenu("Reset Pendulum Position")]
void ResetPendulumPosition()
{
if(this.bobStartingPositionSet)
this.MoveBob(this.bobStartingPosition);
else
this.PendulumInit();
}
// Use this to reset any built up forces
[ContextMenu("Reset Pendulum Forces")]
void ResetPendulumForces()
{
this.currentVelocity = Vector3.zero;
// Set the transition state
this.currentStatePosition = this.Bob.transform.position;
}
void PendulumInit()
{
// Get the initial rope length from how far away the bob is now
this.ropeLength = Vector3.Distance(Pivot.transform.position, Bob.transform.position);
this.ResetPendulumForces();
}
void MoveBob(Vector3 resetBobPosition)
{
// Put the bob back in the place we first saw it at in `Start()`
this.Bob.transform.position = resetBobPosition;
// Set the transition state
this.currentStatePosition = resetBobPosition;
}
Vector3 PendulumUpdate(Vector3 currentStatePosition, float deltaTime)
{
// Add gravity free fall
this.gravityForce = this.mass * Physics.gravity.magnitude;
this.gravityDirection = Physics.gravity.normalized;
this.currentVelocity += this.gravityDirection * this.gravityForce * deltaTime;
Vector3 pivot_p = this.Pivot.transform.position;
Vector3 bob_p = this.currentStatePosition;
Vector3 auxiliaryMovementDelta = this.currentVelocity * deltaTime;
float distanceAfterGravity = Vector3.Distance(pivot_p, bob_p + auxiliaryMovementDelta);
// If at the end of the rope
if(distanceAfterGravity > this.ropeLength || Mathf.Approximately(distanceAfterGravity, this.ropeLength))
{
this.tensionDirection = (pivot_p - bob_p).normalized;
this.pendulumSideDirection = (Quaternion.Euler(0f, 90f, 0f) * this.tensionDirection);
this.pendulumSideDirection.Scale(new Vector3(1f, 0f, 1f));
this.pendulumSideDirection.Normalize();
this.tangentDirection = (-1f * Vector3.Cross(this.tensionDirection, this.pendulumSideDirection)).normalized;
float inclinationAngle = Vector3.Angle(bob_p-pivot_p, this.gravityDirection);
this.tensionForce = this.mass * Physics.gravity.magnitude * Mathf.Cos(Mathf.Deg2Rad * inclinationAngle);
float centripetalForce = ((this.mass * Mathf.Pow(this.currentVelocity.magnitude, 2))/this.ropeLength);
this.tensionForce += centripetalForce;
this.currentVelocity += this.tensionDirection * this.tensionForce * deltaTime;
}
// Get the movement delta
Vector3 movementDelta = Vector3.zero;
movementDelta += this.currentVelocity * deltaTime;
//return currentStatePosition + movementDelta;
float distance = Vector3.Distance(pivot_p, currentStatePosition + movementDelta);
return this.GetPointOnLine(pivot_p, currentStatePosition + movementDelta, distance <= this.ropeLength ? distance : this.ropeLength);
}
Vector3 GetPointOnLine(Vector3 start, Vector3 end, float distanceFromStart)
{
return start + (distanceFromStart * Vector3.Normalize(end - start));
}
void OnDrawGizmos()
{
// purple
Gizmos.color = new Color(.5f, 0f, .5f);
Gizmos.DrawWireSphere(this.Pivot.transform.position, this.ropeLength);
Gizmos.DrawWireCube(this.bobStartingPosition, new Vector3(.5f, .5f, .5f));
// Blue: Auxilary
Gizmos.color = new Color(.3f, .3f, 1f); // blue
Vector3 auxVel = .3f * this.currentVelocity;
Gizmos.DrawRay(this.Bob.transform.position, auxVel);
Gizmos.DrawSphere(this.Bob.transform.position + auxVel, .2f);
// Yellow: Gravity
Gizmos.color = new Color(1f, 1f, .2f);
Vector3 gravity = .3f * this.gravityForce*this.gravityDirection;
Gizmos.DrawRay(this.Bob.transform.position, gravity);
Gizmos.DrawSphere(this.Bob.transform.position + gravity, .2f);
// Orange: Tension
Gizmos.color = new Color(1f, .5f, .2f); // Orange
Vector3 tension = .3f * this.tensionForce*this.tensionDirection;
Gizmos.DrawRay(this.Bob.transform.position, tension);
Gizmos.DrawSphere(this.Bob.transform.position + tension, .2f);
// Red: Resultant
Gizmos.color = new Color(1f, .3f, .3f); // red
Vector3 resultant = gravity + tension;
Gizmos.DrawRay(this.Bob.transform.position, resultant);
Gizmos.DrawSphere(this.Bob.transform.position + resultant, .2f);
/* * /
// Green: Pendulum side direction
Gizmos.color = new Color(.3f, 1f, .3f);
Gizmos.DrawRay(this.Bob.transform.position, 3f*this.pendulumSideDirection);
Gizmos.DrawSphere(this.Bob.transform.position + 3f*this.pendulumSideDirection, .2f);
/* */
/* * /
// Cyan: tangent direction
Gizmos.color = new Color(.2f, 1f, 1f); // cyan
Gizmos.DrawRay(this.Bob.transform.position, 3f*this.tangentDirection);
Gizmos.DrawSphere(this.Bob.transform.position + 3f*this.tangentDirection, .2f);
/* */
}
}
More glamour shots:
Set the maxAngularVelocity on your Rigidbody to Mathf.Infinity.
I know this topic is 9 months old, but I have been banging my head against a wall recently because of this issue. For some reason the Unity developers thought it was a good idea to limit the maximum rotational velocity of rigidbodies to 7 radians per second! That's just a little over one revolution per second, which is way too low for any application that requires physcal accuracy. And on top of that, the property isn't visible in the inspector, or the physics settings!
I hope this will help you (if you haven't figured it out on your own yet) and anyone else who might be fighting with this problem in the future, cheers!
I am developing a 2.5D game. In that game I want my character (which has Rigidbody component attached to) to just move on x and y axises. So I use this code snippet:
private void LockZAxis () {
Vector3 currentPosition = _rigidbody.position;
currentPosition.z = 0;
_rigidbody.position = currentPosition;
}
I call this LockZAxis method in the end of both Update, FixedUpdate and LateUpdate. But it doesn't work. When my character run forward for a while, its z position is still changed.
For additional information, in my code, there are two times I manipulate the position of RegidBody. The first is when my character jump, that time I use this:
jumpVelocityVector = Vector3.up * jumpForceUp + transform.forward * jumpForceForward;
_rigidbody.velocity = jumpVelocityVector;
And each frame when I want my character to move a bit faster, so in the update method, I have this:
void Update () {
Vector3 newPosition = transform.position + transform.forward * speed * Time.deltaTime;
newPosition.z = 0;
_rigidbody.MovePosition (newPosition);
LockZAxis ();
}
A rigidbody is used to simulate physics, by setting the rigidbody's position every frame you're essentially teleporting the character every frame. You can restrict movement in z-axis, this will prevent it to move in z-axis when physics is applied, which is what a rigidbody typically is used for.
Here is how to restrict rigidbody positional change:
If you run your LockZAxis() after you've changed the position it should teleport the object to the z-position of 0 every frame. Please make sure that the z-axis is the correct axis. You can debug this by pausing a running game and manipulating the Transform values to see how each axis moves your Object.
Here is how you can do it with C# Script:
Freeze All Positions
rigidbody.constraints = RigidbodyConstraints.FreezePosition;
Freeze Specific Positions:
rigidbody.constraints = RigidbodyConstraints.FreezePositionY | RigidbodyConstraints.FreezePositionZ;
Unity Documentation
Is physics gravity set to only affect the Y position ?
Physics.gravity = new Vector3(0, -1.0F, 0);
And set these also
rigidbody.angularVelocity = Vector3.zero;
rigidbody.velocity.z=0;
make sure your rigidbody is set to kinematic since you are using Rigidbody.moveposition() and using moveposition() will directly effect velocity internally on a kinematic rigidbody
Try using moveposition() for you jump instead of velocity