I make a 2D-game. In this game, I have a projectile, which I move the fires by myself like this:
void Update()
{
gameObject.transform.position = new Vector3(
gameObject.transform.position.x + baseVelocity * Time.deltaTime,
gameObject.transform.position.y + baseVelocity * Time.deltaTime,
gameObject.transform.position.z);
}
And also, I use void OnTriggerEnter2D(Collider2D other) to know when collisions occurs.
The problem is when game running on a weak phone with 30-FPS it won't detect collision, while same fire in an 60-FPS phone will collide.
I think this is because the fires move 2x more in 30-FPS phones.
One option was use FixedUpdate() method for moving fiers, but it gave me jerky movement, and I used Update() method for moving because it gives me smooth movement(in both of them I used Time.deltaTime).
Can you please suggest me how make more accurate while using smooth movement?
like move object in Update() method but check object position in more(offset) positions than where it is!
I forget to note that I changed the value of Fixed TimeStep to 0.01 for getting more accurate physics.
Thanks in advance.
edit:
I finally end up with using FixedUpdate() for move objects by myself, for so many reasons I can't use Physics engine, I set FixedUpdate TPS(tick per second) around 60 to some how be match with my 60 FPS Update (and still can't figure out why increase FixedUpdate TPS will make object movement jerky!).
And will keep this question open for finding better answer.
You seem to be doing the physics manually. The issue with manually updating the position is that you don't know about the position of your projectile between frames. Even if you were to use FixedUpdate, you could still be in the situation where two FixedUpdate calls cause your projectile to miss an object.
So instead of manually updating the position, you should use a RigidBody2D, with the collision detection set to "Continuous". A continuous collision detection will interpolate object collision in between physics update cycles, so you hit your target even at very high speeds. Also, this solution does not depend on frame rate.
Note that the above will only work if you don't manually update your positions yourself. That is because the physics engine uses velocity to calculate collision in between physics update cycles.
So instead of updating the position yourself (which is bad for physics), use forces instead.
Or alternatively, if you don't want to mess with forces, update the velocity instead:
GetComponent<RigidBody2D>().velocity = baseVelocity;
Related
I'm creating a pool game my problem now is adding a force to ball when it get hits by other ball. Is it ok I'll just adjust the mass of other ball?
There is many ways of doing that, which you can see by searching the Rigidbody Methods in Unity Docs.
One of them, and the one that i use is the AddForce() method because of the ease. Check the official docs for more info: https://docs.unity3d.com/ScriptReference/Rigidbody.AddForce.html
I would suggest that you calculate the direction subtracting de position of both balls in the moment of impact.
About the mass, yes, you can change the mass of the other balls, but i recommend that you study a little bit more of Unity's Physics system in order to achieve your goals, maybe your problem isn't in the balls mass.
Unity has better ways to do this. But I'm assuming you want to find the basics of physics. This explains the power angle obtained by subtracting the position of the hit ball from the striking ball. We normalize it to the unit and you can define the amount of force statically or dynamically.
public float force = 10f;
private void OnCollisionEnter(Collision collision)
{
if (!collision.transform.CompareTag("Ball")) return;
var direction = (transform.position - collision.transform.position).normalized;
collision.transform.GetComponent<Rigidbody>().AddForce(direction*force);
}
To dynamize the force, just multiply the speed of the first ball in it. rigidbody.velocity.magnitude does this, but if rigidbody is used, the above steps are performed automatically and very accurately.
player and object both have colliders and rigidbodies, object has position and rotation locked, player has only rotation locked. When the player goes to the blocks, the player goes through the blocks, although they do give a bit of resistance. To move the player im setting the rigidbody's velocity, and doing that in FixedUpdate.
i have no idea why this is happening, any ideas?
main part of the code is:
rigidBody.velocity = new Vector3(direction.x, rigidBody.velocity.y + (-Gravity * Time.deltaTime), direction.z);
(direction is determined by the WASD keys, and i'm using my own gravity)
First of all, you do not need to multiply the velocity by time.DeltaTime, because you are moving your object in the FixedUpdate() method; Which uses fixed time intervals since the physics engine does not run in sync with the regular game engine. Also, both objects do not need rigidbodies in order to collide with one another. I suggest looking at your collision matrix in settings and verifying that everything you need collision for is checked correctly. As others have said as well, check your kinematics on the rigidbody.
A last suggestion for working with your own gravity. Do not change the actual gravity value of the game engine. It is typically recommended that you use a multiplier variable and apply it to the constant gravity already set by the physics engine. If you are completely editing the gravity, than maybe consider using a character controller instead.
I guess it has something to do with what the documentation says "In most cases you should not modify the velocity directly, as this can result in unrealistic behaviour".
Try to use AddForce() or similar functions to alter the properties of the rigid body. Colliders etc will then work as expected.
I'm going through a few different Unity tutorials and the way a game object is moved around in each is a little different.
What are the pros/cons to each of these methods and which is preferred for a first person RPG?
// Here I use MovePosition function on the rigid body of this component
Rigidbody.MovePosition(m_Rigidbody.position + movement);
//Here I apply force to the rigid body and am able to choose force mode
Rigidbody.AddForce(15 * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
// Here I directly change a transforms position value, in this case the cam
Transform.transform.position = playerTransform.position + cameraOffset;
Thanks!!
EDIT;
Something I have noticed is that the applied force seems to memic wheeled vehicles while the position changes memic walking/running.
RigidBodies and Velocities/Physics
The only time, I personally have used the rigidbodys system was when implementing my own boids (flocking behaviour) as you need to calculate a few separate vectors and apply them all to the unit.
Rigidbody.MovePosition(m_Rigidbody.position + movement);
This calculates a movement vector towards a target for you using the physics system, so the object's velocity and movement can still be affected by drag, angular drag and so on.
This particular function is a wrapper around Rigidbody.AddForce I believe.
Pros :
Good if realistic physical reactions is something you are going for
Cons:
A bit unwieldy to use if all you are trying to achieve is moving a object from point A to point B.
Sometimes an errant setting set too high somewhere (for example: Mass > 10000000) can cause really screwy bugs in behaviour that can be quite a pain to pin down and mitigate.
Notes: Rigidbodies when colliding with another Rigidbody would bounce from each other depending on physics settings.
They are also affected by gravity. Basically they try to mimic real life objects but it can be sometimes difficult to tame the objects and make them do exactly what you want.
And Rigidbody.AddForce is basically the same as above except you calculate the vector yourself.
So for example to get a vector towards a target you would do
Vector3 target = target.position - myPosition;
Rigidbody.AddForce(target * 15 * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
If you don't plan on having any major physics mechanics in your game, I would suggest moving by interpolating the objects position.
As it is far easier to get things to behave how you want, unless of course you are going for physical realism!
Interpolating the units position
Pros :
Perhaps a little strange to understand at first but far simpler to make objects move how you want
Cons:
If you wanted realistic reactions to objects impacting you'd have to do a lot of the work yourself. But sometimes this is preferable to using a physics system then trying, as I've said earlier to tame it.
You would use the technique in say a Pokemon game, you don't stop in Pokemon and wait for ash to stop skidding or hit a wall and bounce uncontrollably backwards.
This particular function is setting the objects position like teleporting but you can also use this to move the character smoothly to a position. I suggest looking up 'tweens' for smoothly interpolating between variables.
//change the characters x by + 1 every tick,
Transform.transform.position.x += 1f;
Rigidbody.MovePosition(m_Rigidbody.position + movement);
From the docs:
If Rigidbody interpolation is enabled on the Rigidbody, calling Rigidbody.MovePosition results in a smooth transition between the two positions in any intermediate frames rendered. This should be used if you want to continuously move a rigidbody in each FixedUpdate.
https://docs.unity3d.com/ScriptReference/Rigidbody.MovePosition.html
Rigidbody.AddForce(15 * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
This will make the object accelerate, so it won't travel at a constant velocity (this is because of Newton's second law, Force=mass*acceleration). Also if you have another force going in the opposite direction this force could get cancelled out and the object won't move at all.
Transform.transform.position = playerTransform.position + cameraOffset;
This will teleport the object. No smooth transition, no interaction with any forces already in the game, just an instant change in position.
I just learn Unity3d for a while, then I have a question about The Camera Follow and Background move are not smooth. I create a cube with ragidbody2d , then i use two dufferent ways to make camera follow :
a. I make the camera in the cube
b. I use Script to control the camera (lateupdate use)
And I add some pictures which are converted into sprite （the size is 1024*512）. I make them to backgound.
when play it , both methods have the same problem, the background move is not smooth, but not completely smooth at all，it will appear from time to time.
I tried the official 2d example found in fast-moving role the backgound is not smooth too. But there are some game made by Unity like badland, when I play it ,there is no this problem.I dont know how to solve this problem, Is the camera configured ? Scirpt? The Type of texture? compressed way? or Need to use some plug-ins?
please help me .thank you .
use "LateUpdate"
LateUpdate is called after all Update functions have been called. This is useful to order script execution. For example a follow camera should always be implemented in LateUpdate because it tracks objects that might have moved inside Update.
It probably because the updates you're using are not synced.
There's the main update (triggered each frame, time between those are different (Time.deltaTime)), FixedUpdate (triggered every physics update, which is a fixed time (Time.fixedTime)) and LateUpdate (every frame, but at the very last).
If you're trying to follow a rigidbody affected by physics, it's recommended to set the camera update function to Late- or FixedUpdate.
You can use it in the Update function if you set the interpolation of the rigidbody in it's inspector:
A rigidody gets an update for it's position every x fixed time, the Update function can be triggered 5 times when FixedUpdate has only been called once, or vice versa. This will give strange results, so setting the rigidbodies interpolation will smooth things out between those unsynced updates.
Also, you can move the camera smoothly by using Lerp methods. an example:
void Update() {
Camera.main.transform.position = Vector3.Lerp(Camera.main.transform.position, targetPosition, Time.deltaTime * 5);
}
more about lerping here
Hope this helps
I found another problem that I don't move camera at all, just move a GameObject which has some pictures as backgound. The Script of Moving GameObject is
Update()
this.transform.Translate(Vector3.right * Time.deltaTime * 40.0f, Space.World);
or
Vector3 pos = this.transform.position;
pos.x += (100.0f * Time.deltaTime);
transform.position = Vector3.Lerp(transform.position, pos, Time.deltaTime * 50);
the reuslt is the background move is not smooth with a visual lag, but not completely smooth at all，it will appear from time to time.
Is there some configures wrong? Graphics Emulation？ or something else ?
I'm creating Unity2D runner where characters is running on the ground.
I'm trying to force him run with constant speed by applying force with right vector but the movement is jerky.
I'm trying to achieve effect of endless run with permanent speed. It is easy in the air but works different (because of physics) when character is running on the ground.
You could velocity and make sure to turn off gravity. If you are running on the ground make sure you turn this off.
You could implement your own movement where you can update position depending on Time.deltaTime.
Just use the built in character controller that unity comes with. basic directionals and jump. And mouse controls where the character faces.
EDIT:
Use rigidbody velocity and turn off gravity and drag. This will keep your runner running forever.
To implement this yourself. You can update the position of the object in the update method. Something like
Vector3 temp = object.transform.position;
temp.x = speed * Time.deltaTime;
object.transform.position = temp;
Where object is you runner and speed is how fast you would like him to move.
This would be inside the update function.
If you aren't going to be controlling the runner, dont bother with the controller
Use Rigidbody2D.velocity and pay attention to:
The velocity can also gradually decay due to the effect of drag if
this is enabled.