at the moment i'm working on a 2D plattformer and the work is going very well. But there is one Problem i can't get rid of.
The player can use a dash, which should move the player very fast in the direction he is looking. My problem is, that the player game object instant appears at the target location... like a teleport.
I'm using the AddForce Function to move the game object. On jumping i'm using AddForce as well and there it works really nice, i get a smooth jump movement.
The only different between dash and jump is that on jump i apply force to the y axis and on dash to the x axis. Changing the amount of force doesn't affect the movement only the distance.
Does anyone have an idea what i'm doing wrong?
// Dash
rigidbody2D.AddForce (new Vector2((dashSpeed * direction), 0));
// Jump
rigidbody2D.AddForce (new Vector2(0, jumpForce));
Best,
Verdemis :)
EDIT: I can not access my project at the moment, but i will try to show you what i have done.
Note: dashSpeed is a float value, at the moment something like 3500
and direction contains 1 or -1, depending on the direction the player is looking. The Dash code is part of the Update method.
// Dash
if(Input.GetKeyDown(dashKey))
rigidbody2D.AddForce (new Vector2((dashSpeed * direction), 0));
What is your direction vector, is it normalized? Since multiplying non-normalized vectors can be rather hazardous. Do you have more of the script to show?
EDIT: You should always do physics things in the FixedUpdate loop(link).
Ok i could solved the problem. My problem was that i only did this AddForce only once. The AddForce code was only executed in a single frame. I added a time which i count down to define how long the dash movement gonna be!
The problem may be that you are using a very big force, I was messing around with some physics today and realized that even a force of 100 almost looks instant. Try making a smaller force number to see if that helps you. I just tested making a smaller number and that does not work.
Related
In the endless running game I am creating, there is a mechanic called the jump pad. It basically takes in the change in the player's position since the last frame and converts that to an angle. Then it uses that along with the transform.rotation of the jump pad to figure out which direction to move the player in, as if it was actually bouncing off of it.
This algorithm would've been working perfectly except for one problem: Unity was reading an incorrect transform.rotation. When the jump pad was rotated 45 degrees, it read 21.92615 (after being multiplied with Mathf.Rad2Deg.) When the jump pad was rotated 20 degrees, it read 9.949307.
At first I thought it was being multiplied by an unknown constant for some reason, but after checking it through the Calculator app I found this to be not exactly the case. After a bit more experimenting I found that the possible "unknown constants", while close enough together, did seem to have a range from around 2 to around 2.1. And while I don't have the faintest clue how this is happening, it does seem to be remarkably consistent.
So my question is: what is this problem I am facing and is there any way I can fix it? Brief side note: I know this is not some other problem with the code because I stripped it down to the bare minimum:
public void OnTriggerEnter2D(Collider2D collision){
Debug.Log(collision.gameObject.transform.rotation.z * Mathf.Rad2Deg);
}
OK. After looking up the scripting API for transform.rotation and messing around a bit, I discovered that it was returning the z value of a quaternion and fixed it using the .ToEulerAngles() call.
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 am trying to move my player by using rigidbody.velocity:
rigidbod.velocity = new Vector2 (Input.GetAxis ("Horizontal") * maxSpeed, rigidbod.velocity.y);
the problem is, this messes up of my explosion code. The character is supposed to be knocked back when near an explosion. I know why it happens; if the player is still, the rigidbody's X velocity would be returned as 0, meaning any outside forces pushing the player along the X axis would counteract this. So when I add the explosion, the player cuts to his new position a few units away. It looks very unnatural and jerky, as he should be pushed back, but his code is telling him to be still unless a key is pressed. I'm posting this to see if there's any way I can re-write this code to be able to move the player while being pushed correctly from outside forces. I heard that AddForce works, but when I used it, my player's velocity constantly increased. He is wither way too fast or way too slow. Any ideas on how I can get this to work? I tried adding rigidbody.velocity.x after where it says 'maxspeed' hoping that it would allow outside force input, and it works, but it messes up the movement code, making him go way too fast. I can't seem to get both the explosions and the movement code to work correctly at the same time. Any help would be greatly appreciated. Thanks.
which is exactly why in the Unity docs they explicitly state:
In most cases you should not modify the velocity directly, as this can
result in unrealistic behaviour.
instead of modifying the velocity directly, you should be using an AddForce(..)
Vector2 force = new Vector2 (Input.GetAxis ("Horizontal") * maxSpeed, 0f);
rigidbody.AddForce(force);
//or if in update:
rigidbody.AddForce(force * Time.deltaTime);
I ran into a problem while making my complex(ish) camera behaviour (using Javascript). The problem that i have run to is that i am not able to get the position behind my player. Please don't tell me to use Vector3.back etc.. , because i want the position locally, to support turning. It won't work if the camera is always set to that position, cos i have a cool movement system in place.
I tried a number of approaches, and confused myself with the math. I also tried complex addition and subtraction. None of them worked at all.
I guess i am probably missing something quite simple, like a way to get into local coordinates etc.. ( or maybe a few math functions )
thanks in advance
-Etaash
You can get the forward vector of any transform, and if you negate that it is the backward vector. So on a script attached to the player you would have:
Vector3 backward = -transform.forward;
So to get a position, you could do something like this:
Vector3 pos = transform.position + (backward * dist); // where dist is a float to scale how far away from the position you want it
I'm using the first person controller for my characters movement. On a left arrow keypress, I'd like the character to instantly rotate 90 degrees and keep moving forward. Currently, when I hit the arrow key, the character makes the sharp 90 degree turn, but the forward momentum the character previously had takes a second to wear off so the character ends up sliding in the direction he was previously moving a short bit.
The closest example I can think of to visually explain what I'm trying to do is how the character turns sharp in Temple Run. How my game is currently working, if I had the character on a ledge make a sharp left turn, he'd likely keep the original momentum and slide off the edge right after he turns.
Since my character is running on the x/z axis, I'm wondering if there would just be some way to maybe swap the directional velocity/momentum? The speed the character had on the x axis would instantly be switched to the z when it turns and the other would be set to zero. I'm obviously open to any solution that accomplishes what I'm looking for.
I dug into the CharacterMotor class in the first person controller, but have yet to find what part I can tweak to accomplish this.
I'd greatly appreciate any help.
Thank you.
You can try to stop the velocity of the Rigidbody before turning.
this.rigidbody.velocity = Vector3.zero;
this.rigidbody.angularVelocity = Vector3.zero;
If you want the object to continue like it did, you can try playing around with it by saving the current velocity in a variable, setting it to 0, rotate it and then putting back the old velocity (still forward).
If it works with global vectors (so from the point of view of the world, not the object), then you can try negativing the velocity, actually causing it to go 'backwards'. I can't test it for now but either way I think you need to set the velocity to zero first before turning the character.