I am trying to fire projectiles from a player who is moving at very high speeds. The issue is that the bullets do not seem to inherit the angular velocity. If the player is moving in a straight line at 500 U/s, then the bullet correctly inherits that velocity and adds its own speed onto that:
GameObject bullet = Instantiate(projectile, gun.transform.position, gun.transform.rotation);
bullet.GetComponent<Rigidbody>().velocity = r.velocity + bullet.transform.forward *bulletSpeed;
However, if the player is turning really quickly, it does not inherit the rotational velocity, and the bullet looks like it veers off to the side.
How can I implement this? I tried assigning the angular velocity of the player to the bullet, but this just caused the bullet to spin while moving in the same direction.
Some extra details:
I am using rigidbody.MoveRotation() to rotate my player, but I manually calculated angularVelocity to assign it to the bullet
I tried moving the player with AddTorque(), but could not produce any results with the bullets
The immediate problem is that the projectile isn't part of the physics simulation until the moment you create and launch it, meaning the rotation of the player up to that point will not be able to influence its movement. I suppose this could work if you created the projectile at the start, attached it to the gun with a weak joint, then broke the joint and added to its velocity when it was fired - but it really would be simpler if you just "faked" it.
Applying Circular Motion
This is similar to a classic circular motion example you'd find in a physics textbook. When your bullet travels in a circle around the player (inside the gun), its normal path (if released) would be tangent to the circular path around the player. So when the bullet is fired (and hence released from the circular path), that angular velocity of the player would translate into a linear velocity of the bullet. Here's a simple diagram I put together that represents the situation with a ball on a string, being spun in a circle:
Getting the Tangential Velocity of the Bullet
You don't want to be applying any kind of angular velocity to the projectile after it has been launched - as you saw, this will only spin the projectile on its own axis. Rather, you want to apply an additional velocity vector to the projectile, which is tangent to the rotation of the player (and perpendicular to the facing of the bullet). So how do we do this?
Well, as per this website, the formula for tangential velocity at any point on something spinning in a circle is:
velocity = angularVelocity x radius
A key point to remember is that the angularVelocity is in radians, not degrees.
So, let's put this all together. Here's a general idea of how you might code this:
FireGun() {
// Assumes the current class has access to the rotation rate of the player
float bulletAngularVelocityRad = Mathf.Deg2Rad(rotationRateDegrees)
// The radius of the circular motion is the distance between the bullet
// spawn point and the player's axis of rotation
float bulletRotationRadius =
(r.transform.position - gun.transform.position).magnitude;
GameObject bullet =
Instantiate(projectile, gun.transform.position, gun.transform.rotation);
// You may need to reverse the sign here, since bullet.transform.right
// may be opposite of the rotation
Vector3 bulletTangentialVelocity =
bulletAngularVelocityRad * bulletRotationRadius * bullet.transform.right;
// Now we can just add on bulletTangentialVelocity as a component
// vector to the velocity
bullet.GetComponent<Rigidbody>().velocity =
r.velocity + bullet.transform.forward * bulletSpeed + bulletTangentialVelocity;
}
Hope this helps! It's never a bad idea to read up on some basic kinematics/mechanics when you're working with game physics, since sometimes relying on the game physics is actually more complicated than just devising your own solution.
Related
I'm currently trying to make a game to put my relatively new coding knowledge to test. I figured I learn a lot quicker by just doing things and seeing what happens. I'm currently working on a plane and the last couple of days I made a functional camera system (to rotate around the player based on the mouse) and some animations of the plane. I'm currently trying to create a movement system in which the down key rotates the player up. I noticed however that my AddForce function doesn't do what I want it to do. I'd like the plane to move in the Z axis depending on the current rotation of said plane instead of it just heading into the Z angle of the world.
I'm currently working on this snippet:
//Acceleration
if (gameObject.CompareTag("Player") && playerRb.velocity.z > -349)
{
playerRb.AddRelativeForce(0, 0, -playerSpeed, ForceMode.Acceleration);
}
else if (gameObject.CompareTag("Player") && playerRb.velocity.z < -349)
{
playerRb.velocity = new Vector3(playerRb.velocity.x, playerRb.velocity.y, -350);
}
//
//Movement
//Up/down controls
if (gameObject.CompareTag("Player") && Input.GetKey(KeyCode.DownArrow))
{
transform.Rotate((0.07f * playerSpeed) * Time.deltaTime, 0, 0);
}
As you can see I already tried AddRelativeForce as another topic mentioned but that doesn't seem to work for me. The moment it hits an edge it just falls down into the abyss regardless of it's rotation.
Additionally, I was considering using another AddForce function on the rotate as it doesn't leave the ground (considering it keeps hitting the floor with its tail), is there any way to apply a force on an object from a specific position/angle? (such as the front of the plane).
Thanks in advance!
I think the reason your plane is acting strange is not because of your addrelative force call -- it's because you are setting velocity. playerRb.velocity = new Vector3(playerRb.velocity.x, playerRb.velocity.y, -350); assigns the velocity to push you -350 in the world's z axis, which probably isn't what you want. Velocity is in the global space. Remove that and see what happens.
On a more general note, If you're using physics, try to use only forces and torquees. Using transform.Rotate to change a rigidbody's rotation while physics is active will just make your life difficult, and make the rigidbody do strange things. I do change the velocity of rigidbodies sometimes, but not in every frame. I just don't know enough about physics to mess with velocities that way.
Also, make sure you're doing these things in a FixedUpdate function, since that is where input that affects physics is supposed to be checked.
This is a school project. I have a big cube which is like a planet. I have a small cube that can move on every side of the cube planet. The player moves forward automatically on its local z axis and I rotate it by 90 or -90 degrees to move left or right- but the player can control it like it's an up-down-left-right movement (made a script so they don't have to rotate the cube with 2 keys). It's like a Tron game so if I press the up key, I can't press down immediately because I leave a trail so I have to press the left or right keys. I have a problem with my camera movement. The camera follows the little cube from above, but I want it to lean a little when the little cube player gets close to the edge of a side so it lets me see the other side - where I'm planning to go.
I have a script where I use the center of the cube planet and the player's center as the direction vector and multiply it with the camera-player distance.
Vector3 direction = (target.position - center.position).normalized;
transform.position = target.position + direction * distance;
Then I point my camera's forward vector to the player cube's direction. I tried two codes but none of them worked perfectly. First I tried to rotate the camera with:
transform.rotation = Quaternion.LookRotation(-direction);
Shown in video. The problem with this is that since I don't tell the program the Up and Right vectors (I think), it sets them for itself to some random numbers so the camera sometimes do its own thing like it does a pirouette.
Next I tried this:
Quaternion rot = Quaternion.FromToRotation(transform.forward, -direction);
transform.Rotate(rot.eulerAngles, Space.World);
Shown in video. It's almost good but as the little cube moves, the camera starts steering slightly in the beginning and it gets worse and worse.
Do you have any ideas how can I make it work? I hope you understand what I would like to achieve. I'm trying to set the camera as to always show that when I press Up, my cube moves upward, when I press Right my cube always goes right etc. and when I reach the edge of my side the camera leans a bit towards the side I'm moving to.
Use dot product to find which orthogonal direction of your cube is closest to the camera's current up.
Vector3 closestToUp;
float greatestDot = 0f;
foreach (Vector3 dir in new Vector3[]{
target.forward, target.right, -target.forward, -target.right})
{
float curDot = Vector3.Dot(dir,transform.up);
if (curDot > greatestDot)
{
greatestDot = curDot;
closestToUp = dir;
}
}
Than, use that direction as the second parameter of Quaternion.LookRotation. This will keep its local up direction as aligned with the cube's "top" as possible given whatever new forward direction:
transform.rotation = Quaternion.LookRotation(-direction, closestToUp);
I am coding for a game and I have it running fine and all, but I ran into the issue of projectiles. I have no idea of how to calculate the mouse position and send a projectile over. I've looked though many stackoverflow tutorials and many youtube videos, but they are either too vague or very very complex. Could someone please explain the process? I have been coding in C# for 2 years now, so I do have background knowledge. Please Help!
Well, you don't tell what kind of game you are working on and what the projectile you want to "send over", whatever that means but here are a few pointers, maybe one will help:
#1: If you are doing a 2D game, and you want to send a projectile from some point toward the mouse cursor, then you simply get the position of the mouse by calling GetState() on your MouseState instance, and reading it's X and Y properties, then get the direction of the projectile by subtracting the location of the origin of the projectile from the mouse position. Then you can move the projectile along that line by storing the time you launched it, subtracting that every frame from the actual time to get how long it has been on its way and then adding that many times it's speed times the normalized direction to its origin coordinates.
Example:
For this I assume you have a Projectile class that has Vector2 field called origin, one called direction, one called position, a float called speed and an int called startTime and you have an instance of it with origin and speed already set. Modify as necessary for your actual code.
MouseState ms = new MouseState();
in your Update method:
ms.GetState();
projectile.direction = new Vector2(ms.X, ms.Y) - projectile.origin;
projectile.direction.Normalize();
projectile.position = projectile.origin + projectile.speed * (gameTime.TotalGameTime.TotalMilliseconds - projectile.stratTime) * projectile.direction;
And then in the Draw method you just draw the projectile to the coordinates in projectile.position.
#2: You are doing a 3D game and want to shoot a projectile originating from your camera and directed toward whatever your mouse is pointing at. You will need to generate a Ray with something like this:
private Ray getClickRay(Vector2 clickLocation, Viewport viewport, Matrix view, Matrix projection)
{
Vector3 nearPoint = viewport.Unproject(new Vector3(clickLocation.X, clickLocation.Y, 0.0f), projection, view, Matrix.Identity);
Vector3 farPoint = viewport.Unproject(new Vector3(clickLocation.X, clickLocation.Y, 1.0f), projection, view, Matrix.Identity);
Vector3 direction = farPoint - nearPoint;
direction.Normalize();
return new Ray(nearPoint, direction);
}
From there you can get the position of your projectile the same way as above, only using Vector3-s instead of Vector2-s.
#3: You want to simulate some sort of launcher and do a physical simulation on the trajectory of the projectile. Since I find this less likely than the first two I'll just describe the idea: you set a minimum and maximum rotation for your launcher along 2 axes, link each rotation to the ratio of the full width and length of your screen to the mouse position, and then use the angles and whatever other variables you have to calculate the direction and speed of the projectile at launch, then simulate physics each frame.
I hope one of these will help.
I have a very simple model for a plane that can move around in the x and y directions, while an ocean scrolls by to make it look as though the plane is flying. Whenever the plane moves, I adjust its roll and pitch.
I compute and maintain the position, roll and pitch, inside the object script. Every update step I re-assign them to the Unity properties of the object.
The problem comes where I tried to add a barrel-roll effect. This code works fine:
transform.Translate(position - transform.position);
Vector3 rotChange = new Vector3 (-pitch, 0, -roll) -
transform.rotation.eulerAngles;
transform.Rotate (rotChange);
So long as I'm keeping all the rotation within +- 30 degrees. When the plane is doing a barrel roll, it updates each step with the following:
velocity = new Vector3 (barrelRollDirections.x * barrelRollXSpeed,
barrelRollDirections.y * barrelRollYSpeed, 0);
roll += barrelRollTurnSpeed * Time.deltaTime;
if (roll < -(fullRotation/2)) {
roll += fullRotation;
}
if (roll > (fullRotation/2)) {
roll -= fullRotation;
}
The funny thing is that spinning the plane around actually works properly if the plane isn't moving along the x or y axis when I do it. But if it is, it jumps all over the place and only reappears in the proper final position once the roll is over.
I tried a number of ways to fix this problem:
-Convert my desired orientation to a quaternion using Quaternion.Euler and assigning that directly to transform.rotate. This didn't solve anything, and it also causes the plane to jitter and shake while at the bounds of its movement.
-Save the initial orientation of the plane in a quaternion, then, every update step, reassign that initial rotation to the plane and THEN call Transform.Rotate(new Vector3(-pitch,0,-roll)). I thought this would solve my problem if it was something like gimbal lock, since then I would just, every step, be applying rotations that were less than 180 degrees. But no dice.
EDIT: I found it! After asking this question, I figured I'd go work on different objects since I was waiting for an answer. There I discovered that the transform.Translate function moves objects in a different direction based on their rotation. When I changed to simply reassigning the position, it worked fine. As per usual, the act of talking to someone else helped to resolve the issue.
I am new to programming and I am making a 2D side-scrolling beat em' up for my project. I got an AI working for my enemies but my enemy objects are modelled to be flat so only one side is meant to be shown. When I start my game, the enemies immediately rotates to face the player when i wanted it to stay as it is but still move towards the player.
http://i.imgur.com/TJYtfro.png This is what I want the enemies to stay as, just having this face shown as it slides towards the player without rotating or tilting.
http://i.imgur.com/n0gI2Rf.png This is what happens when I start the game which is why I do not want the objects to rotate or tilt. If you want additional informations of what I have done or if I am unclear, just let me know. It is my first time asking online.
This is the code I got for the enemyAI. I know the code is all wrong when it comes to what I wanna achieve but I have very limited coding knowledge and still learning.
//------------Variables----------------//
public Transform target;
public int moveSpeed;
public int rotationSpeed;
public int maxdistance;
private Transform myTransform;
//------------------------------------//
void Awake()
{
myTransform = transform;
}
void Start ()
{
maxdistance = 2;
}
void Update ()
{
if(Vector3.Distance(target.position, myTransform.position) > maxdistance)
{
//Move towards target
transform.LookAt (target.position);
myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
}
}
Your problem is that you have some confusion over what "forward" means. You need to decide which direction forward is. Currently, "forward " is "out of the screen", because you're doing a 2D side scroller and you have all of your enemies facing out of the screen.
However, you're trying to use LookAt() to make the characters look at the player. But then of course they'll turn, because "forward" for each enemy mesh/model is currently the direction facing out from their face.
You have two options. One is to rotate all of your models 90 degrees so that forward is coming out their side. In this case, you could still use LookAt() and then tell the enemies to move forward, but visually they'd still be looking out of the screen. However, the enemies would turn around backwards if you got onto their other side. So probably not a good option.
The other option is that you shouldn't be setting the enemy transform/position using the "forward" vector. Just set the enemy position based on a vector that's the difference between the enemy position and the player position. Subtract the enemy position vector from the player position vector and you'll have a vector pointing in the direction of the player. Normalize it to get a unit direction vector. Then multiply that by the move speed and delta time as you have above. Use that instead of "forward" and your enemies will toward the player. In this case, you don't call the LookAt() at all, because you always want the enemies facing out of the screen.
EDIT: I don't have a copy of Unity, but it should be something like this:
if (Vector3.Distance(target.position, myTransform.position) > maxdistance)
{
// Get a direction vector from us to the target
Vector3 dir = target.position - myTransform.position;
// Normalize it so that it's a unit direction vector
dir.Normalize();
// Move ourselves in that direction
myTransform.position += dir * moveSpeed * Time.deltaTime;
}