I have a script attached to a mesh with a kinematic, rigid body with a convex mesh collider that I'd like to move around. Here's what I call in my update function:
if (Input.GetKey(forwards)) {
Debug.Log("forwards!!");
//get current velocity in local space
Vector3 localVel = transform.InverseTransformDirection(body.velocity);
//alter so that forward component = speed
localVel = new Vector3(localVel.x, localVel.y, linearSpeed);
//convert back into world space and set to body
Vector3 worldVel = transform.TransformDirection(localVel);
body.velocity = worldVel;
}
Other Info:
body is a Rigidbody variable that I assign in Start() using GetComponent<Rigidbody>();
linearSpeed is a float with value 1
I'm getting the Debug.Log output, but my mesh is not moving. Is there anything obvious I'm missing here? This is my first script for a 3D, as opposed to a 2D game.
public float speed = 20;
Rigidbody r;
void Start(){
r = gameObject.GetComponent<Rigidbody> (); //Put's reference to local rigidbody into variable "r"
}
void FixedUpdate () {
Vector3 direction = Vector3.zero; //set's current direction to none
//Adds vectors in case that user is pressing the button
if(Input.GetKey(KeyCode.W)) direction += Vector3.forward;
if(Input.GetKey(KeyCode.S)) direction -= Vector3.forward;
if(Input.GetKey(KeyCode.D)) direction += Vector3.right;
if(Input.GetKey(KeyCode.A)) direction -= Vector3.right;
//Normalizez direction (put's it's magnitude to 1) so object moves at same speeds in all directions
r.AddForce (direction.normalized * speed); //Adds direction with magnitude of "speed" to rigidbody
}
Rigidbody MUST be attached to same GO as this script. This script uses world directions, because working with local directions is much harder (the object is rotating and changes directions rapidly, you can use it if you want just by replacing reference to Vector3 to transform like this:
if(Input.GetKey(KeyCode.W)) direction += transform.forward;
Of course for all direction.
This is very basic way to move the object along it's local axises, to do it more better you need to write specific scripts for specific sets of objects, it all depends what kind of object are you moving and how you want to move it. (is it sphere, cube..., will it ever fly up, should it rotate....).
If the RigidBody is Kinematic it is meant to be moved by means other than the physics system; animations, transform.position, etc. Make your rigid body non-kinematic and it should move when you set velocity.
Related
I'm trying to figure out simple custom 2D physics for platformer. At the moment I'm using ray casts to figure out collision between the player and map. However using ray cast has some problems. For example, if the player is falling (has somewhat high downwards velocity) its unable to pick up holes in the wall because it moves past them due to going too far down to be detected as empty space.
One solution is to move to tile based system instead of using ray casts but I would preferably not to do so.
So I'm wondering is there some kinda solution to figure out empty holes in wall, even small edge ones without huge performance impact.
High quality drawn illustration, assume leftwards velocity:
Physics2D.BoxCast is how I would tackle this. It does what you expect, instead of a ray it calculates as if a full box was traversing the distance.
Usage is very similar to raycasting. Example:
public Collider2D mainCollider;
public Vector2 velocity;
void Update() {
Vector2 origin = new Vector2(transform.position.x, transform.position.y);
Vector2 size = mainCollider.bounds.size;
Vector2 direction = velocity * Time.deltaTime;
float maxDist = velocity.magnitude;
var hit = Physics2D.BoxCast(origin, size, 0, direction, maxDepth);
if (hit == null) {
transform.position += direction;
} else {
transform.position += direction.normalized * hit.distance;
}
}
If boxes are not your taste, there's also a Physics2D.CapsuleCast and Physics2D.CircleCast.
Im trying to move an object in a 3d world using a controller, but think I am missing something cus it just clips away as soon as I give any input:
private void Update()
{
float h = Input.GetAxisRaw("Horizontal");
float v = Input.GetAxisRaw("Vertical");
Vector3 movement = new Vector3(h, 0, v).normalized * Time.deltaTime * speed;
if(h != 0 || v != 0)
_rigidBody.MovePosition(movement);
}
Works fine using _rigidbody.velocity, but as I understand it that should be avoided for these types of things.
Rigidbody.MovePosition sets the position of the rigidbody with interpolation. It looks like you want to offset the position by movement, so you should probably set the velocity. If you do still want to use MovePosition, you should do _rigidBody.MovePosition(transform.position + movement);.
"using a controller"
Do you mean Character Controller Component? You have 2 options and they are both well explained in Unity Documentation.
Second is by Rigidbody Component.
I create a game and I need use inertia for object.
Example:
The image shows all what I need.
When I touch on screen, blueObject no longer uses the position of brownObject and rotation of redObject. And I add component Rigidbody. The object just falls down. I need him to fall further along his trajectory (inertia).
I tried to use addForce(transform.forward * float), this not work.
By setting the position of the transform, you don't use Unity Physics engine. Your cube must have a rigidbody from the begin of the simulation and what you need here is a spring joint (https://docs.unity3d.com/Manual/class-SpringJoint.html) or a fixed joint.
You need to calculate the current speed, when releasing the object.
Track the positions over the last frame & current frame, and use Time.deltaTime to compensate different frame-rates.
Then set this velocity to your objects rigidbody. (AddForce is just manipulating the velocity, but depending on the ForceMode it respects mass etc.)
public Vector3 lastPosition = Vector3.zero;
void Update()
{
// maybe do : if(lastPosition != Vector3.zero) to be sure
Vector3 obj_velocity = (lastPosition - transform.position) * Time.deltaTime;
lastPosition = transform.position;
// if you release the object, do your thing, add rigidbody, then:
rb.velocity = obj_velocity;
}
That should create the "inertia". the velocity contains the direction and the speed.
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
I am trying to create a third person spaceship movement.
The spaceship rotates about all axes at its position, and has a throttle control to move in forward direction. There is a camera which is always behind it. I am not making the camera a child because I want the camera to NOT follow the rotation about z axes.
The camera has a script, which keeps its position a fixed distance behind the spaceship, and then calls transform.LookAt(spaceShipTarget).
The problem is that as I rotate the ship around global x axes 90 degrees, the y axis of camera suddenly does a 180 degree rotation. The camera control script is below:
using UnityEngine;
namespace UnityStandardAssets.Utility
{
public class FollowBehind : MonoBehaviour
{
public Transform target;
public float distance;
public float delay;
private Vector3 velocity = Vector3.zero;
private void LateUpdate()
{
Vector3 offset = target.transform.TransformVector(0, 0, distance);
Vector3 currentPosition = transform.position;
Vector3 finalPosition = target.position + offset;
transform.position = Vector3.SmoothDamp(currentPosition,
finalPosition, ref velocity, delay);
transform.LookAt(target);
}
}
}
Why would that happen and how can I fix it?
The problem you have with the rotation of the camera is probably caused by the script you use to make the camera follow the spaceship, probably because when you rotate the spaceship the rotation (and probably the position) of the camera are affected.
What you could do instead is make both the spaceship and camera child of another object, and then add a script to this parent object. Now you can put some code in the script of the parent to move the parent itself (this way both camera and spaceship will move together, and you don't need to keep them together manually) and also in the script of the parent you can put some code to rotate the spaceship and camera individually or together based on specific inputs.