Develop Reference

Why the speed variable have no factor when changing in the inspector the value in run time ? How to update positions and make nonstop moving?

The main goal is to move the object between the positions with a delay. This is working fine but other things are not working.
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
public class Waypoints : MonoBehaviour
{
public GameObject objectPrefab;
public LineRenderer lineRenderer;
public List<Transform> pointsToMove;
public float speed;
public bool go = false;
private List<GameObject> objectsToMove;
private List<Vector3> positions;
void Start()
{
objectsToMove = new List<GameObject>();
//Spawn objects and start movement
}
private void Update()
{
if (go && lineRenderer.positionCount > 0 && CurvedLineRenderer.linesSet)
{
positions = GetLinePointsInWorldSpace();
foreach(Transform objToMove in pointsToMove)
{
positions.Add(objToMove.position);
}
for (int i = 0; i < 3; i++)
{
objectsToMove.Add(Instantiate(objectPrefab, transform.parent));
StartCoroutine(Move(i));
}
go = false;
}
}
private IEnumerator Move(int i)
{
//Wait interval
yield return new WaitForSeconds(i * 10);
bool stillTraveling = true;
int pointIndex = 0;
float threshold = 0.1f;
while (stillTraveling)
{
//Check if close to point
if (Vector3.Distance(objectsToMove[i].transform.position, positions[pointIndex]) < threshold)
{
//Check if can move next point
if (pointIndex + 1 > positions.Count - 1)
{
stillTraveling = false;
}
//If not stop moving
else
{
pointIndex++;
}
}
//Move towards point
objectsToMove[i].transform.position = Vector3.MoveTowards(objectsToMove[i].transform.position, positions[pointIndex], speed * Time.deltaTime);
yield return null;
}
}
List<Vector3> GetLinePointsInWorldSpace()
{
var pointsToMove = new Vector3[lineRenderer.positionCount];
//Get the positions which are shown in the inspector
lineRenderer.GetPositions(pointsToMove);
//the points returned are in world space
return pointsToMove.ToList();
}
}
I'm updating once the positions in the Update.
I'm using StartCoroutine once in the Update to send the objects to move between the waypoints with a delay.
private void Update()
{
if (go && lineRenderer.positionCount > 0 && CurvedLineRenderer.linesSet)
{
positions = GetLinePointsInWorldSpace();
foreach(Transform objToMove in pointsToMove)
{
positions.Add(objToMove.position);
}
for (int i = 0; i < 3; i++)
{
objectsToMove.Add(Instantiate(objectPrefab, transform.parent));
StartCoroutine(Move(i));
}
go = false;
}
}
It's working by sending the objects to move with delay between the waypoints, but now I have some other problems.
Because I'm using StartCoroutine for the delay and because I'm setting the go flag to false then the speed value have no affect on the moving objects at run time and I'm not sure how to solve it so the speed will have a factor affecting the moving objects.
Another problem or not a problem but not sure how to do it is how to Update in run time the positions List ? Here in the Update I'm updating the List once :
positions = GetLinePointsInWorldSpace();
foreach(Transform objToMove in pointsToMove)
{
positions.Add(objToMove.position);
}
but I want that if the amount of positions in the function GetLinePointsInWorldSpace or/and the amount of pointsToMove have changed to update the positions List at rune time. I could just call this part in the update nonstop but I'm not sure of it will be too expensive ?
Last problem or how to do is how to make the object to move to move between the waypoints non stop over again from the start or moving backward when getting the last waypoint ? Again because using StartCoroutine for the delay everything is happening once.

If you want to move an object from one point to another, you should use Mathf.Sin(). The is using the sine function, and you put in the amount of cycles times Mathf.PI times 2. Here is what you would write:
float period = 2f;
Vector3 a; //the first point the object goes to
Vector3 b; //the second point that the object goes to
void Update()
{
float cycles = period * Time.time * Mathf.PI;
float amplitude = Mathf.Sin(cycles);
Vector3 location = Vector3.Lerp(a, b, amplitude);
Transform.position = location;
}
I then use Vector3.Lerp to interpolate between point a and point b. This isn’t what you were doing, but it is a much simpler way you can do it.
Vector3 a; //the first point the object goes to
Vector3 b; //the second point that the object goes to
void Update()
{
float cycles = period * Time.time;
Vector3 location = Vector3.Lerp(a, b, cycles);
Transform.position = location;
}
This one is for bringing the object just strait to point b and not back.
If you want there to be a delay between when it moves, here is the script:
float period = 2f;
float waitTime;
bool AtoB = true;
Vector3 a; //the first point the object goes to
Vector3 b; //the second point that the object goes to
void Start()
{
StartCoroutine(“Oscillator”);
}
IEnumerator Oscillator
{
float amplitude;
if (AtoB)
{
amplitude += Time.deltaTime * period;
}
else
{
amplitude -= Time.deltaTime * period;
}
amplitude = Mathf.Clamp(amplitude, 0, 1);
Vector3 location = Vector3.Lerp(a, b, amplitude);
Transform.position = location;
if (amplitude == 1)
{
AtoB = false;
yield return new WaitForSeconds(waitTime);
}
if else (amplitude == 0)
{
AtoB = true;
yield return new WaitForSeconds(waitTime);
}
else
{
yield return false;
}
}

Unity2D: Enemy doesn't follow Player when in its radius

Hey Guys I've been having a problem lately that I cant seem to solve.
A sprite is supposed to roam around (as it does) while nothing is inside its radius, however if the player moves close to it the sprite should theoretically move towards it and stop roaming.
The sprite doesn't follow the player and cant even see its tag since I cant even see the contents of the "Collider2D[] hits".
using System.Collections.Generic;
using UnityEngine;
public class FireCultist : MonoBehaviour
{
public float moveTimeSeconds; //Time it will take object to move, in seconds.
private float xMax = 10.0f; // The boundaries of the spawn area
private float yMax = 10.0f;
private float xMin = -10.0f; // The boundaries of the spawn area
private float yMin = -10.0f;
public int xDistanceRange; // The max distance you can move at one time
public int yDistanceRange;
private BoxCollider2D boxCollider; //The BoxCollider2D component attached to this object.
private Rigidbody2D rb2D; //The Rigidbody2D component attached to this object.
private float inverseMoveTime; //Used to make movement more efficient.
public Vector2 start;
public Vector2 end;
public bool roam = true;
public Collider2D[] hits;
void Start()
{
boxCollider = GetComponent<BoxCollider2D>();
rb2D = GetComponent<Rigidbody2D>();
inverseMoveTime = 1f / moveTimeSeconds;
InvokeRepeating("RandomMove", 0.0f, 5.0f);
}
void Update()
{
Collider2D[] hits = Physics2D.OverlapCircleAll(transform.position, 10); // returns all colliders within radius of enemy
int i = 0;
while(hits.Length > i)
{
Debug.Log("Sees");
Debug.Log(hits[i]);
i++;
}
followPlayer();
if (roam)
{
Debug.Log("Roam");
transform.position = Vector2.MoveTowards(transform.position, end, inverseMoveTime * Time.deltaTime); //Random move to new position
}
}
public void followPlayer()
{
foreach (Collider2D hit in hits)
{
if (hit.tag == "Player") // if the player is within a radius
{
Debug.Log("Chasing Player");
transform.position = Vector2.MoveTowards(transform.position, GameObject.Find("Prefabs/Player").GetComponent<Transform>().position, inverseMoveTime * Time.deltaTime); // chase player
roam = false;
}
else
{
Debug.Log("Continues");
roam = true; // Continue RandomMove()
}
}
}
public void RandomMove() // gets random coordinates near enemy and moves there
{
float xDistance = Random.Range(-xDistanceRange, xDistanceRange); // check
float yDistance = Random.Range(-yDistanceRange, yDistanceRange);// check
if (xDistance < xMax && xDistance > xMin && yDistance < yMax && yDistance > yMin && roam == true) // If within boundaries of walking space
{
start = transform.position;
end = start + new Vector2(xDistance, yDistance);
Debug.Log("Roaming From : " + start + " To : " + end);
}
}
}
The roaming algorithm works however not too sure about the tag detection.
The script belongs to this enemy object
Player Object Properties

It looks like you are declaring a new hits variable during every update instead of using your class-level variable. This means the variable inside of followPlayer() will never be instantiated, and the information will not be passed between the two methods.
Try this:
void Update()
{
hits = Physics2D.OverlapCircleAll(transform.position, 10);
//...
}
You might also consider attaching a trigger collider to the enemy which sends a notification when the player enters/exits the trigger instead of relying on OverlapCircleAll()
void OnTriggerEnter2D(Collider2D col)
{
if(col.gameObject.tag == "Player"){
roam = false;
}
}
void OnTriggerExit2D(Collider2D col)
{
if(col.gameObject.tag == "Player"){
roam = true;
}
}

How can i calculate the rotation the player need to make to get to the next waypoint?

using System.Linq;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
public class Waypoints : MonoBehaviour
{
public GameObject[] waypoints;
public Transform target;
public float moveSpeed = 10f;
public float slowDownSpeed = 3f;
public float reverseSlowDownSpeed = 3f;
public float rotationSpeed = 1f;
private int targetsIndex = 0;
private Vector3 originalPosition;
private GameObject[] players;
public Transform reverseTarget;
private int reverseTargetsIndex = 0;
private Vector3 reverseOriginalPosition;
public bool random = false;
public bool getNextRandom = true;
// Use this for initialization
void Start()
{
waypoints = GameObject.FindGameObjectsWithTag("Blocks");
players = GameObject.FindGameObjectsWithTag("Player");
originalPosition = players[0].transform.localPosition;
}
// Update is called once per frame
void Update()
{
if (random == true)
{
RandomWayPointsAI();
}
else
{
WayPointsAI();
}
}
private void WayPointsAI()
{
if (targetsIndex == waypoints.Length)
targetsIndex = 0;
target = waypoints[targetsIndex].transform;
if (MovePlayer())
targetsIndex++;
}
private void ReverseWayPointsAI()
{
if (reverseTargetsIndex == 0)
reverseTargetsIndex = waypoints.Length - 1;
reverseTarget = waypoints[reverseTargetsIndex].transform;
if (MovePlayer())
reverseTargetsIndex--;
}
void RandomWayPointsAI()
{
if (random == true && getNextRandom)
{
int index = UnityEngine.Random.Range(0, waypoints.Length);
target = waypoints[index].transform;
getNextRandom = false;
}
getNextRandom = MovePlayer();
}
bool MovePlayer()
{
float distance = Vector3.Distance(players[0].transform.position, target.transform.position);
players[0].transform.localRotation = Quaternion.Slerp(players[0].transform.localRotation, Quaternion.LookRotation(target.position - players[0].transform.localPosition), rotationSpeed * Time.deltaTime);
//move towards the player
if (distance < 30)
{
players[0].transform.localPosition += players[0].transform.forward * slowDownSpeed * Time.deltaTime;
}
else
{
players[0].transform.localPosition += players[0].transform.forward * moveSpeed * Time.deltaTime;
}
if (distance < target.transform.localScale.magnitude)
return true;
else
return false;
}
void DrawLinesInScene()
{
// draw lines between each checkpoint //
for (int i = 0; i < waypoints.Length - 1; i++)
{
Debug.DrawLine(waypoints[i].transform.position, waypoints[i + 1].transform.position, Color.blue);
}
// draw a line between the original transform start position
// and the current transform position //
Debug.DrawLine(originalPosition, players[0].transform.position, Color.red);
Debug.DrawLine(reverseOriginalPosition, players[1].transform.position, Color.red);
// draw a line between current transform position and the next waypoint target
// each time reached a waypoint.
if (target != null)
Debug.DrawLine(target.transform.position, players[0].transform.position, Color.green);
if (reverseTarget != null)
Debug.DrawLine(reverseTarget.transform.position, players[1].transform.position, Color.green);
}
void AddColliderToWaypoints()
{
foreach (GameObject go in waypoints)
{
SphereCollider sc = go.AddComponent<SphereCollider>() as SphereCollider;
sc.isTrigger = true;
}
}
}
There are two problems with the script.
If the Move Speed is set to 3 i need to set the Rotation Speed at least to the 10 if i will set the Rotation Speed to 3 or 4 or 5 the rotation will be too wide and it will take much time to the player to get back on track after rotating.
But if it's 10 it seems he is almost rotating on the place so it's not good either.
I want to be able to change the player rotation speed but also to keep him on the waypoints track at any time. I mean that each waypoint the player is reaching to that he will get to it's center. In this case cubes so not only to touch the waypoint but to get to it's center then moving to the next waypoint.
Another problem i see is with the RandomWayPointsAI()
When i change it to use the random method i'm not sure if it's just picking up random positions around the grid or if it's picking random blocks(Cubes).
But it's never getting to a cube it' getting close or between two or sometimes on a cube and same as before also on the random i want to make the random waypoints not just positions but blocks and to get to each random block center.
Center i mean like standing on it.

A glaring problem in the showcased code is the use of local positions and rotations. When moving and rotating characters and objects in the world you should use world space.
Localposition and localrotation are based on the position and rotation of the parent object. Using those to move your object across the world will cause weird problems.
I think the following answer has a pretty accurate explanation of that stuff https://teamtreehouse.com/community/global-space-vs-local-space

Why in some cases when the player is moving to the left he is leaving in 1.5 distance the grid area?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using System.IO;
public class DirsFinder : MonoBehaviour
{
public Transform player;
public float playerMoveSpeed = 1f;
public float playerRotationSpeed = 0.5f;
public float distanceToTravel = 1.5f;
public bool randomDir = true;
private Transform start;
private Transform end;
private GridGenerator gridgenerator;
private List<Vector3> possibleDirections = new List<Vector3>();
private Vector3 selectedDirection;
private float m_distanceTraveled = 0f;
private List<Vector3> visitedList = new List<Vector3>();
private List<Vector3> toBeVisitedList = new List<Vector3>();
private Vector3 playerPosition;
public void FindDir()
{
gridgenerator = GetComponent<GridGenerator>();
GenerateStartEnd();
FindDirections();
m_distanceTraveled = 0;
}
private void FindDirections()
{
possibleDirections = new List<Vector3>();
playerPosition = player.localPosition;
m_distanceTraveled = 0;
if (playerPosition.x > 0)
{
// can go left
possibleDirections.Add(Vector3.left);
}
if (playerPosition.x + gridgenerator.spaceBetweenBlocks < gridgenerator.gridWidth * gridgenerator.spaceBetweenBlocks)
{
// can go right
possibleDirections.Add(Vector3.right);
}
if (playerPosition.z > 0)
{
// can go backward
possibleDirections.Add(Vector3.back);
}
if (playerPosition.z + gridgenerator.spaceBetweenBlocks < gridgenerator.gridHeight * gridgenerator.spaceBetweenBlocks)
{
// can go forward
possibleDirections.Add(Vector3.forward);
}
if (randomDir == true)
{
selectedDirection = possibleDirections[Random.Range(0, possibleDirections.Count)];
}
player.forward = selectedDirection;
}
private void Update()
{
if (m_distanceTraveled < distanceToTravel)
{
Vector3 oldPosition = player.position;
player.position += selectedDirection * Time.deltaTime * playerMoveSpeed;
m_distanceTraveled += Vector3.Distance(oldPosition, player.position);
}
if (m_distanceTraveled >= distanceToTravel)
{
FindDirections();
}
}
private List<Vector3> GenerateStartEnd()
{
GameObject walls = GameObject.Find("Walls");
List<Transform> wallsParents = new List<Transform>();
List<Vector3> startEndPos = new List<Vector3>();
foreach (Transform child in walls.transform)
{
wallsParents.Add(child);
}
for (int i = 0; i < 2; i++)
{
wallsParents.Remove(wallsParents[Random.Range(0, wallsParents.Count)]);
}
var childsWall0 = wallsParents[0].GetComponentsInChildren<Transform>().ToList();
var childsWall1 = wallsParents[1].GetComponentsInChildren<Transform>().ToList();
childsWall0.RemoveAt(0);
childsWall1.RemoveAt(0);
start = childsWall0[Random.Range(0, childsWall0.Count)];
player.position = start.position;
end = childsWall1[Random.Range(0, childsWall1.Count)];
end.tag = "End";
startEndPos.Add(start.position);
startEndPos.Add(end.position);
start.GetComponent<Renderer>().material.color = Color.red;
end.GetComponent<Renderer>().material.color = Color.blue;
return startEndPos;
}
}
In the method FindDirections i assign the player to be facing to the selected random direction:
player.forward = selectedDirection;
Then in the Update i'm moving the player to specific distance each time 1.5f And checking when the player traveled 1.5 distance call FindDirections again and over again. I checked with a break point it keep getting back to the FindDirections and getting a new random direction.
But in some cases when the player is walking to the left since it's random i saw it on the left side only so far didn't see it yet on the right side of the grid.
But when he is getting to the left in some cases he is keep moving by 1.5 out of the grid left wall out of the grid.
In the screenshot two cases where the player left the grid area on the left then he walk on this area and then back to the grid area.
It started when i started to move the player with the limit distance of 1.5 and the travel distance.
Not sure why it happen.

Your problem might be caused by floating-point precision.
This piece of code
if (playerPosition.x > 0)
…evaluates true if playerPosition.x is a small value such as 0.000001.
You could avoid this by using small margin in comparison.
const float margin = 0.001f;
...
if (playerPosition.x - margin > 0f) // (pos.x - bounds.leftx) < margin
Better approach would be to use integers as grip positions.
Another thing is that you update player.position in Update() but use player.localPosition in FindDirections(). I’m not sure if this is intended.
(However, if the player transform has no parent, localPosition is same as position.)
EDIT: You could also force the player position to nearest multiple of 1.5f before setting a new direction:
if (m_distanceTraveled >= distanceToTravel)
{
// round x and z to nearest multiple of distanceToTravel
var tmpPos = player.position;
tmpPos.x = Mathf.Round(player.position.x / distanceToTravel) * distanceToTravel;
tmpPos.z = Mathf.Round(player.position.z / distanceToTravel) * distanceToTravel;
player.position = tmpPos;
FindDirections();
}

How can i make the Invisible Walls script to work and take effect?

The idea is to make that when the player is walking to the edge of the terrain he will stop wont be able to continue and fall.
And in my case i want the objects that move forward when they collide with the invisible wall the object will turn lerp back and move to the other side of the invisible walls.
Another problem that might come up later i read about is that if the objects moving too fast to the invisible walls there is a bug that let them move through ? Not sure about it.
This is a screenshot showing the invisible walls. I created a box collider set the Is Trigger to be on and set the 500 600 500 same as the terrain size.
This is the script of the Invisible Walls: The script i attached it to the Terrain:
using UnityEngine;
using System.Collections;
public class InvisibleWalls : MonoBehaviour {
// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
}
void OnTriggerExit(Collider other)
{
}
}
This is the script that create the space ships clone of them and make them move forward. But when they get to the edge of the terrain they just gone out. And i want them to lkerp/turn back to the other side.
This script is attached to the Spheres GameObject:
using System;
using UnityEngine;
using Random = UnityEngine.Random;
using System.Collections;
using System.Collections.Generic;
public class SphereBuilder : MonoBehaviour
{
public GameObject SpaceShip;
GameObject[] spheres;
public float moveSpeed = 50;
// for tracking properties change
private Vector3 _extents;
private int _sphereCount;
private float _sphereSize;
/// <summary>
/// How far to place spheres randomly.
/// </summary>
public Vector3 Extents;
/// <summary>
/// How many spheres wanted.
/// </summary>
public int SphereCount;
public float SphereSize;
private void Start()
{
spheres = GameObject.FindGameObjectsWithTag("MySphere");
}
private void OnValidate()
{
// prevent wrong values to be entered
Extents = new Vector3(Mathf.Max(0.0f, Extents.x), Mathf.Max(0.0f, Extents.y), Mathf.Max(0.0f, Extents.z));
SphereCount = Mathf.Max(0, SphereCount);
SphereSize = Mathf.Max(0.0f, SphereSize);
}
private void Reset()
{
Extents = new Vector3(250.0f, 20.0f, 250.0f);
SphereCount = 100;
SphereSize = 20.0f;
}
private void Update()
{
UpdateSpheres();
MoveShips ();
}
private void MoveShips()
{
foreach (Transform child in spheres[0].transform)
{
child.transform.position += Vector3.forward * Time.deltaTime * moveSpeed;
}
}
private void UpdateSpheres()
{
if (Extents == _extents && SphereCount == _sphereCount && Mathf.Approximately(SphereSize, _sphereSize))
return;
// cleanup
var spheres = GameObject.FindGameObjectsWithTag("Sphere");
foreach (var t in spheres)
{
if (Application.isEditor)
{
DestroyImmediate(t);
}
else
{
Destroy(t);
}
}
var withTag = GameObject.FindWithTag("Terrain");
if (withTag == null)
throw new InvalidOperationException("Terrain not found");
for (var i = 0; i < SphereCount; i++)
{
var o = Instantiate(SpaceShip);
o.tag = "Sphere";
o.transform.SetParent(gameObject.transform);
o.transform.localScale = new Vector3(SphereSize, SphereSize, SphereSize);
// get random position
var x = Random.Range(-Extents.x, Extents.x);
var y = Extents.y; // sphere altitude relative to terrain below
var z = Random.Range(-Extents.z, Extents.z);
// now send a ray down terrain to adjust Y according terrain below
var height = 10000.0f; // should be higher than highest terrain altitude
var origin = new Vector3(x, height, z);
var ray = new Ray(origin, Vector3.down);
RaycastHit hit;
var maxDistance = 20000.0f;
var nameToLayer = LayerMask.NameToLayer("Terrain");
var layerMask = 1 << nameToLayer;
if (Physics.Raycast(ray, out hit, maxDistance, layerMask))
{
var distance = hit.distance;
y = height - distance + y; // adjust
}
else
{
Debug.LogWarning("Terrain not hit, using default height !");
}
// place !
o.transform.position = new Vector3(x, y, z);
}
_extents = Extents;
_sphereCount = SphereCount;
_sphereSize = SphereSize;
}
}
And this is a small short video clip showing what happen to the space ships when they get to the terrain edge:
Spaceships video clip
Update what i did so far:
In top of script added:
public Terrain terrain;
private Vector3 boundLower;
private Vector3 boundUpper;
In Start function i added:
private void Start()
{
spheres = GameObject.FindGameObjectsWithTag("MySphere");
var withTag = GameObject.FindWithTag("Terrain");
if (withTag == null)
throw new InvalidOperationException("Terrain not found");
boundLower = terrain.transform.position - terrain.transform.size / 2;
boundUpper = terrain.transform.position + terrain.transform.size / 2;
}
But getting errors on both lines: size property not exist:
boundLower = terrain.transform.position - terrain.transform.size / 2;
boundUpper = terrain.transform.position + terrain.transform.size / 2;
And changed the MoveShips function to this:
private Vector3 direction = Vector3.forward;
private void MoveShips() {
foreach (var child in spheres) {
var pos = child.transform.position + direction * Time.deltaTime * moveSpeed;
pos.x = Mathf.Clamp(pos.x, boundLower.x, boundUpper.x);
pos.z = Mathf.Clamp(pos.z, boundLower.z, boundUpper.z);
if (pos.x == boundLower.x || pos.x == boundUpper.x) direction.x = - direction.x;
if (pos.z == boundLower.z || pos.z == boundUpper.z) direction.z = - direction.z;
child.transform.position = pos;
}
}

I would suggest modifying MoveShips() changing Vector3.forward to a variable and flipping it when bounds are reached:
private Vector3 direction = Vector3.forward;
private void MoveShips() {
foreach (var child in spheres) {
var pos = child.transform.position + direction * Time.deltaTime * moveSpeed;
pos.x = Mathf.Clamp(pos.x, boundLower.x, boundUpper.x);
pos.z = Mathf.Clamp(pos.z, boundLower.z, boundUpper.z);
if (pos.x == boundLower.x || pos.x == boundUpper.x) direction.x = - direction.x;
if (pos.z == boundLower.z || pos.z == boundUpper.z) direction.z = - direction.z;
child.transform.position = pos;
}
}
This will remove unnecessary dependence on object collision engine for such a simple thing. Note, how this is making all ships to change direction when furthest reaches the bound. If you want them to move separately, you will need to move this logic to a separate script and attach it to a ship prefab.
And the bounds (boundLower and boundUpper) can be set either as script variables in editor or calculated from terrain, like:
boundLower = terrain.transform.position - terrain.TerrainData.size / 2;
boundUpper = terrain.transform.position + terrain.TerrainData.size / 2;
I would also suggest to move this:
var withTag = GameObject.FindWithTag("Terrain");
if (withTag == null)
throw new InvalidOperationException("Terrain not found");
out of Update() into Start() unless you do something really funky with it in the process.

Lets start working though your problems one by one :
Question : The objects do not collide, why?
Answer : Objects do not collide from with-in the collider, only from the outside.
What you need in your case is 4 box collider, one at each edge of the map
Question : Another problem that might come up later i read about is that if the objects moving too fast to the invisible walls there is a bug that let them move through ? Not sure about it.
This is only a problem with objects moving at bullet-like speeds, you could edit the rigidbody to have detection mode : "continuous" or continuous-dynamic which will avoid this issue
The scripts, i do not think you would need them in this case, your original idea was good, just the implementation with a single collider over the whole terrain, instead of 4 seperate "wall" colliders, was the issue. As for the rest of the logic, i did not try decipher through that, thus i can not comment on it.