I'm making a game where I have a skeleton as a game object:
Since this skeleton is an enemy, I want to make it walk on its own, and turn around as it reaches the edge, and so on. I managed to make it walk like so:
void Update() {
if (isWalking) {
body.velocity = new Vector2((isFacingLeft ? -1 : 1) * speed, body.velocity.y);
.
.
.
where isWalking is set to true from the beginning for testing purposes, speed is 5, and isFacingLeft is a boolean I want to flip whenever the skeleton reaches an edge, initially it is false, so the skeleton travels to the right without stopping.
So the idea I had is make use of OnCollisionEnter2D which should work since the skeleton is on top of the platform game object, and use the collision object to get different bounds:
From the picture, if the game object platform can be called L and its width y, then I'm thinking of getting the necessary bounds of it by finding Lx and Lx + y. Then, if the skeleton's width can be called x, I would want to measure the transform.position.x of the skeleton and check: if it faces right, and transform.position.x > Lx + y - x (or maybe x / 2 to approach it a bit more to the edge), then flip the isFacingLeft boolean. If it's facing left and transform.position.x < Lx + x (or x / 2), flip the boolean.
However, if I try logging the left edge (via collider.transform.position.x) and the skeleton position (via transform.position.x), I get starting values of 6.4596, 5.943441, meaning that the skeleton somehow starts before the platform. Is it possible that transform is not the right property to check for bounds in this case? How then can I ensure I'm using the desired values to check edges? If anyone knows, please comment even if you have questions about my approach, as going over the thought process really helps to get an answer.
So as suggested by pocokknight on reddit, I tried implementing ray casting, so that there is a ray projecting from a bottom corner of the skeleton sprite depending on what position it should face, achievable via SpriteRenderer.bounds.size. If the ray projected doesn't hit anything the position the skeleton would face flips. This enables the skeleton to turn around back and forth forever :)
RaycastHit2D hit = Physics2D.Raycast(new Vector2(transform.position.x + ((enemyWidth / 2) * direction), transform.position.y - enemyHeight / 2), transform.TransformDirection(new Vector2(1 * (direction), -1)), 1f);
Of course, this is a very simple execution of the function, and I could probably think of scenarios where the raycast check could fail (such as if the player object is right on its path when it should be checking for empty ground), but thus far it's a progress I'm happy with
Related
I have four rectangular platforms put around a square platform. All other three rectangular platforms were rotated from the '0' platform. On the end of each rectangular platforms, I set up some spawn points to generate cubes with arrows sign on its face(the image of this cube is shown in the second link). I hope to rotate the cube to change the orientation of the arrow on it. But my original codes that rotating the cube do not work for platform 1 & 3, but work for platform 0&2.
Although I have found how to change it to make it works, I still cannot understand why my original codes failed. The version I used is 2019.4.18f1.
The top view of these platforms are shown below.
enter image description here
Unworkable way
dirCubeTypes is an array that stores all my different kinds of cube objects.
dirCubePoints is an array that stores all my spawn points.
The first statement works well. The problem is in the second statement.
GameObject cube = Instantiate(dirCubeTypes[Random.Range(0, 6)], dirCubePoints[Random.Range(0, 4)]);
cube.transform.Rotate(transform.forward, 90 * Random.Range(0, 4));
The figure below shows the cube generated on the platfrom 3. I want it to rotate around z-axis, but the codes above make it rotate around its x-axis instead of z-aixs. I know the third parameter is relativeTo, and the default value is Space.self. Why doesn't the codes above make it rotate along the z-axis in its own local coordinate system?
enter image description here
Workable ways
I have tried out three workable ways, but for two of them, I still don't know why it works.
This one works well. If I use Vector3.forward in Space.self, I think it should rotate around the x-axis of the cube itself, but it rotate around its z-axis.
GameObject cube = Instantiate(dirCubeTypes[Random.Range(0, 6)], dirCubePoints[Random.Range(0, 4)]);
cube.transform.Rotate(Vector3.forward, 90 * Random.Range(0, 4));
This one also works well. But I am confused either.
GameObject cube = Instantiate(dirCubeTypes[Random.Range(0, 6)], dirCubePoints[Random.Range(0, 4)]);
cube.transform.Rotate(transform.forward, 90 * Random.Range(0, 4), Space.World
);
The last one is the only one that works as I think.
GameObject cube = Instantiate(dirCubeTypes[Random.Range(0, 6)], dirCubePoints[Random.Range(0, 4)]);
cube.transform.RotateAround(transform.position, transform.forward, 90*Random.Range(0,4));
First of all
Vector3.forward just equals new Vector3(0,0,1) so it is just a generic Z axis vector (either in the world or local depending on how it is used)
transform.forward rather is the local Z axis of your object in world space
And Rotate can either be used in world space or in local space (this is the default since the space parameter is optional and defaults to Space.Self).
When you passed in
cube.transform.Rotate(transform.forward * 90 * Random.Range(0,4));
it of course behaves strange since you treat the world space vector transform.forward like a local space one. So as soon as your object is somehow rotated in the world it breaks.
So either you want the world space then do
// Using the world space transform.forward and passing in Space.World
cube.transform.Rotate(transform.forward * 90 * Random.Range(0,4), Space.World);
or the same in local space
// Using the local space Vector3.right
// in this case - since it will use Space.Self if nothing is passed in -
// the Vector3.forward is treated as relative to the local space
cube.transform.Rotate(Vector3.forward * 90 * Random.Range(0,4));
I just saw your question update. I believe your misunderstanding stems from not knowing what Vector3.forward and Transform.forward are and their core difference. Vector3.forward is the unit vector defined by (0, 0, 1). The Transform.forward is a relative direction based on the orientation of your object.
Your first example works in some cases as it just so happens that the Transform.forward and Vector3.forward happen to be the same direction.
Your second example works as you are using Vector3.forward not the relative Transform.forward
Your third example works as you provide the Space.World, so instead of using local orientations, it is rotating the object in world space relative to the scene.
Your fourth example works as you are using RotateAround. RotateAround is different than Rotate in that it will rotate the transform about your inputted axis (transform.forward), which pass through the point (transform.position) in world coordinates by the angle (90*Random.Range(0,4)) degrees. Effectively moving the local rotation around an axis back to world space.
I hope this clears up why the first example does not work while the last three do.
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.
This 'object' is a rectangle in 2D coordinates. (Game is in Unity 3D)
With Rigidbody.velocity.z I can know if the object is moving right or left, but how can I know if this object (a spaceship) is moving to its own right or left?
Imagine a spaceship that accelerates forward. Then after a while the ship rotates 90°, having its right side now aligned with the direction of movement. If then the ship rotates 180°, it will have its left side aligned with the direction it is moving.
I think another way of asking would be, how to know in which side of the ship is the vector of movement?
Context
The ship has a maximum speed. If the ship is at maximum speed and it needs to change direction, first it has to slowdown. If the vector of the ships movement is somewhere to its right side, then it has to add a force pushing against it, rigidbody.addForce (transform.left * force)
(I haven't written this in the code yet, but below "headed" is the normalized vector of where the ship is headed, and shipDirection is the normalized vector of the ships direction. Supposedly when they match is when ship is pointed at where it is going, but I have to test it first)
if (throttle > 0) {
if (headed != shipDirection) {
if (body.velocity.z > 0)
Rigidbody.addForce (transform.right * force);
if (body.velocity.z < 0)
Rigidbody.addForce (transform.left * force);
}
}
The problem above is that transform.right or transform.left can be at either side depending on the object orientation, so it could either speed or slow the ship.
You can perform the dot product of the velocity with any directional vector to give the component in that direction. E.g. Vector2f.DotProduct(Rigidbody.velocity, Rigidbody.right) will be positive if the object is moving to its own right, and vice versa.
I want to move a camera closer to an object in Unity, so that the zooming is linear. Take a look at the zooming in the Scene window in the Unity Editor. The camera isn't moving with a constant speed. The more zoomed in you are, the slower the camera moves. And I do want to move the camera, I don't want to change the FOV.
First off, yes do not use the FOV to do that, it would be a massive pain to control the movement. Being in low FOV, would mean you are focus on a tiny part and movement would be hard to control since one unit would be a large movement in small FOV. Also, a large FOV creates fish eye effect. So nope.
One way you could achieve this fast to slow effect is to use a distance to define the amount of movement
Let's consider you use the mouse wheel to zoom in and out, you listens to the value and create a movement based on that.
float movement = Input.GetAxis("Mouse ScrollWheel");
if(movement == 0)
{
return;
}
Transform camTr = Camera.main.transform;
float distance = Vector3.Distance(camTr.position, origin.position) + 1;
camTr.Translate(camTr.forward * distance * movement * Time.deltaTime * speed);
speed variable is meant to control how fast regardless of the distance. Distance gets a plus 1 so you can still move while real close to the origin.
The origin position needs to be defined, it could be based on a raycast going forward from the camera and hitting at y = 0. Just an idea. It could also be a focused object, that all depends on what you are doing.
The whole point here is that your camera will move faster if you are far from the focus point. Also, you may want to clamp the movement so that begin far away does not result in gigantic movement.
i propose you to use FOV (because player feel good)
1- use Transform.localPosition to change distance of camera to near or far - you should change z axis to changing distance of camera
2- use camera rendertotexture and in GUI change scale of it ( isn't good because need pro unity license and get allot of memory);
but can't know whats reason for you want forget changing FOV
One step of perspective projection of a point is the division by distance of that point. This means that the projected size of any object does not change linearly with its distance.
projectedSize = originalSize / distance
So if you want to approach an object in a way that its projected size grows linearly, you'll have to change your distance non-linearly.
We do this by also dividing the distance by some value f. The exact value of f depends on the stepSize and (I think) the FoV of your camera.
By using FixedUpdate() instead of Update() we make sure we have a constant stepSize which allows us to assume f as being constant as well.
void FixedUpdate()
{
newDistance = oldDistance / f;
}
For the definition of f you can use any value bigger than, but close to 1. For example f = 1.01f. This will approximate the desired behaviour quite well. If you want it to be perfectly linear, you'll have to dig deeper into the calculations behind perspective projection and calculate the exact value of f yourself: https://en.wikipedia.org/wiki/3D_projection#Perspective_projection
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