Develop Reference

Unity Addforce Bug

I'm currently working on a simple 2d jump and run game. I want to move my player with physics (using addforce).
In the editor, my player jumps at a normal height. But when i build the game it suddenly jumps way higher. I put everything in fixedUpdate() and don't know where the problem is?
//Movement
rb.velocity = new Vector2(horizontalMove, rb.velocity.y);
//Jump
if (jumpPressed)
{
if (isGrounded)
{
rb.AddForce(new Vector2(0f, jumpForce), ForceMode2D.Impulse);
anim.SetTrigger("takeOf");
}
}
Dan

If jumpPressed is true for every frame when the jump key is held, this could be the issue. This would mean that the code could act several times, reapplying the upwards force several times (before it goes far away enough from the ground that the ground check does not detect it). If this is the case, it can be fixed by:
rather than using AddForce, set the vertical velocity to the velocity of the jump.
changing the jumpPressed to only return true if jump was pressed this frame
Imposing a limit to how often you can jump (if you cannot jump twice within 0.1 seconds, that could fix the issue)

Character moves slow when parented to moving platform

I'm working on a 2D platformer game in Unity. My character moves by applying velocity to the rigid body and works just as I want it to for precise controls.
When the character is on a moving platform, I parent the character to the moving platform so that the character stays on while the platform moves. Here's the code that's on the moving platform
private void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.tag == "Player")
{
collision.collider.transform.SetParent(transform);
}
}
private void OnCollisionExit2D(Collision2D collision)
{
if (collision.gameObject.tag == "Player")
{
collision.collider.transform.SetParent(null);
}
}
I'm also using transform.position from one position to another to move the platform.
Here's the issue. The character works perfectly fine only if the speed of the platform is 0. If the platform is moving at all, the character will move like a slug while walking on the platform. Any ideas on how to fix the issue or is there a way to have the character ride on the moving platform without parenting it to it?
Edit: I forgot to include this earlier. I've tested to see if the physics materials would make a difference. I included a 0 friction physics material on the character, the platform, and both at the same time. None of the combinations made any difference. The player still move sluggish while the platform is moving.

If you are moving your character with a force and a rigidbody, the hierarchy and who is the parent is not going to have much influence as the movement is provided by the force, this is with the physics.
If you where manipulating the transform in the code for the movement that would be important, but if movement is produced by forces I think its not.
I would check the frictions of the Physic Materials of the player and the platform in order to define the movement of the elements respect each other.

It is quite a while for the answer but I think I found one. Moving the platform in FixedUpdate rather than in Update can fix this issue.

Instantiate and Fire Object, when OnTriggerEnter or OnCollisionEnter

I would like a bullet that is fired from the Enemy, to bounce back off my Players shield.
I have set up my character and the enemy fires towards me at time intervals.
I can then activate my players shield (turning on a BoxCollider) and pressing a button.
So when the Bullet (IsTrigger) collides with my Players Shield (IsNotTrigger) I want to remove this Bullet and then Instantiate a new Bullet from the shield, in the direction of the Enemy.
I am also having an issue destroying the Bullet.
When the OnTriggerEvent or OnColliderEvent occurs (tried both), hundreds of bullets will appear from my Shield. How do I only allow one bullet to be fired towards the enemy?
Below is part of my script, which is located in the GameObject of my Players Shield.
Ideally I would like to destroy the bullet once it has collided with an object.
void OnTriggerEnter(Collider col) {
if (col.tag == "Weapon") {
attack();
}
}
private void attack() {
if (!GameManager.instance.GameOver) {
bulletReturnClone = Instantiate(bulletReturn, transform.position, transform.rotation) as GameObject;
bulletReturnClone.GetComponent<Rigidbody>().velocity = transform.forward * 25f;

Strachan,
That's not how I would approach the problem but I will stick to your desired solution then share some ideas for improvement.
void OnTriggerEnter(Collider col) {
if (col.tag == "Weapon") {
attack(col);
}
}
private void attack(Collider col) {
if (!GameManager.instance.GameOver) {
bulletReturnClone = Instantiate(bulletReturn, transform.position, transform.rotation) as GameObject;
bulletReturnClone.GetComponent<Rigidbody>().velocity = transform.forward * 25f;
// the following line of code should remove the bullet from the shield collider in order to prevent any future problems like spawning multiple bullets or instantly destroying the newly created bullet
bulletReturnClone.GetComponent<Transform>().position *= bulletReturnClone.GetComponent<Rigidbody>().velocity;
Destroy(col.gameObject);
}
}
If your trigger(Bullet) is tagged as weapon this code should achieve your intentional goal of reflecting the bullet in the direction of your shield pointing to by destroying the bullet and instantiating a new one and modifying it's velocity. It works but it's kind of sloppy development. It can be much better if you approach the problem from a different perspective - the one of the Bullet not the Shield.
Let's pretend for a moment you are a Bullet. All you do is fly in the direction you are shot. Once you collide with a terrain you stop/disappear. If this terrain is a shield you don't stop/disappear but change your direction (you get reflected).
So... long story short... the one who should have a trigger collider is the bullet not the shield. OnTriggerEnter(Collider col) for the bullet script will destroy it but if col.tag == "Shield" the bullet will only change its direction without all the useless instantiations and transformations.
I'm too lazy to write the code for the 2nd solution. If you got my point you should be able to easily write it down. Also learning through trials and errors helps you develop (excuse for me being lazy).

Im not really sure why you would want to despawn and respawn the bullet with a new velocity?
Depending on the shield geometry you could look up Coefficients of Restitution and therefore reflect the kinetic energy of the bullet into a realistic velocity.
Note the complexity of that maths will be proportional to the complexity of your shield geometry depending on the different collision primitives.
Sphere-sphere
Sphere-plane
Sphere-terrain (terrain could represent any un-even surface)
Or are you trying to collect the bullets in some sort of "charge" mechanic to release them back at a different time?

Unity.Check if object is coliding with another in a function

I'm making a game (similar to Subway Surfers), and I have a floor made of many small cubes. And I want to make my game do something when the player stops colliding with the floor. But when I use OnTriggerExit (Collider other) I never know if the player stops colliding the floor or just moves from one piece of the floor to another:
OnTriggerExit (Collider other){
if (other.tag == "floor") {
if(/*Object isn't coliding with any other object with the tag "floor" (Or simply isn't coliding with the other piece of the floor) */){
//Do something
}
}
}

It depends on the needs of the game. Since you named Subway Surfer, I would go with the z-coordinate of the player.
I would add the heightFromGround field to the player class (calculated as the difference on the z-axis between the player and the platform underneath).
Then, if heightFromGround is higher than a threshold, you know the player is jumping.
This also allows you to control the Animation of the character based on it's height from the ground (so he can prepare to land) and transition to the running state.
To have different platforms at different heights, you need to know the platform currently underneath the player at runtime.
This is just an approach to avoid collision checking.
If you don't need that level of control on Animations and prefer to keep using collisions, you can simply add a field int touchingPlatforms = 1; and add 1 to it OnCollisionEnter, subtract 1 from it OnCollisionExit. The player is jumping if touchingPlatforms is 0.

How to Prevent RigidBody from passing through other colliders

I've got a coin RigidBody and walls around it with box colliders. For trial purpose I've applied the following code to the coin.
private void OnMouseDown()
{
rigidbody.AddForce(30.0f, 0f, 5.0f, ForceMode.Impulse);
}
But, sometimes the coin passes through the walls, but when I increase the speed from 30 to 50 points it passes through the walls on the first click. I've googled a lot and still got nothing except for the DontGoThroughThings Script which doesn't work for me or I don't really know how to use it.
I've always added a continuous dynamic on the coin and continuous collision detection on the walls but still doesn't work.

the problem with physics collision detection is that sometimes when the speed of an object is too high (in this case as a result of a force added to the rigid body) the collision wont be detected. The reason is that the code you are executing is running at x ammount of steps per seconds so sometimes the rigidbody will go through the collider between one step to another. Lets say you have a ball at 100 miles per hour and a wall that is 1 feet wide, the code will move the ball a determined ammount of feets everytime the code is runned according the physics of it, so the movement of the ball is virtualized but its not a real physical movement so it can happen that from one step to another the ball can move from point a to b and the wall is between those points and as a result the collision will not be detected.
Possible Solutions.
You have a simple solution that wont be as accurate as it should be and a harder one that will be perfectly accurate.
The solution number one will be increasing the colliders size, according to the max speed your coin can get, that way the collider will be big enough so that the collision wont be missed between one frame to another.
The second and harder solution will be adding an auxiliar to your collision detection, some kind of a security check. For example using physical raycast. You can set a raycast to forward direction and determine if that object is an inminent collision, if it does and once the object isnt being collided by the raycast anymore then your collision detection had failed that way you have your auxiliar to confirm that and call the collision state.
I hope it helped and sorry about my english. If you didnt understound it very much i could help you with code but i will need some code from your project.

See if the colliders have their 'Is Trigger' unchecked.
Also, check if the gameObjects have colliders.

I have faced this problem many times..
Make sure Your coin's Rigidbody has "Is Kinamatic" False, Is Triggger:false,
And also "Is Trigger" of walls is False.

You could save the velocity and position on each update and then test for out of bounds, if the coin leaves the valid area you can restore it at the last valid position or plot the collision yourself if you want to