Limiting Turret Rotation on Tank

Hi Everyone. This should not be as hard as it is but I'm just trying to limit the up/down motion of the barrel of the tank. Here's a video that hopefully illustrates the problem.

I'm just using Transform.Rotate (Vector3. up and Vector3.Right for the turret base and barrel's rotation since they are two separate objects and it seems to work fine but I just cannot get the clamping to work on the up/down motion when using the transform.Rotate(Vector3.Right. It's funny that you can make the tank look like it's on a pogo stick but not optimal for making the barrel behave realistically.

Any suggestions would be appreciated.

Here's the relevant code...


Thanks!

public class TurretRotate_SciFiTank : MonoBehaviour
{

//Rotating Key Variables

public GameObject sciFiTurretBase; //reference to the turret base of the cannon for side to side movement
public GameObject sciFiBarrel; //reference to the actual barrel of the cannon for up/down movement

public string turretLeft; //key to rotate turret to left
public string turretRight; //key to rotate turret to Right
public string turretUp; //key to rotate turret barrel Up
public string turretDown; //key to rotate turret barrel Down

public Quaternion barrelRotation; //quaternion to hold angle of barrel
public float barrelRotX;
public Quaternion baseRotation;
public float baseRotY;

//public float maxBarrelRot;
//public float minBarrelRot;


public Transform sciFiShotPoint; //position in space to instantiate energy weapon of cannon
//public GameObject sciFiWeapon; //reference to the weapon prefab
public string shootKey; //reference to the shoot key of the weapon.

public GameObject plasmaProjectile; //projectile of sciFi Tank
//public GameObject plasmaMuzzleFlash; //muzzle flash effect for plasma

// Use this for initialization
void Start ()
{

}

// Update is called once per frame
void Update ()
{
//CANNON MOVEMENT INPUTS
if (Input.GetKey(turretRight))
{
//baseRotY += Time.deltaTime * 100f;
sciFiTurretBase.transform.Rotate (Vector3.up * 50f * Time.deltaTime);
}

if (Input.GetKey(turretLeft))
{
//baseRotY -= Time.deltaTime * 100f;
sciFiTurretBase.transform.Rotate (Vector3.up * -50f * Time.deltaTime);
}

if (Input.GetKey(turretUp))
{
//barrelRotX += Time.deltaTime * 100;
sciFiBarrel.transform.Rotate (Vector3.right * 40f * Time.deltaTime);
}

if (Input.GetKey(turretDown))
{
//barrelRotX -= Time.deltaTime * 100;
sciFiBarrel.transform.Rotate (Vector3.right *-40f * Time.deltaTime);


}

 

Volume was super quiet in the video, but I got the idea anyways
Please refer to this page for posting code on the forums: https://forum.unity.com/threads/using-code-tags-properly.143875/
It will show up looking much nicer.

One of the easiest solutions to your situation is keep track of the angle of (local)rotation.
It goes up/down based on input.. next, you clamp it before assigning it.
Lastly, of course, you assign it. Maybe :

Code (csharp):

1. barrel.rotation = Quaternion.Euler(value, barrel.rotation.eulerAngles.y,/* z if used or 0 */);
2. // use localRotation instead maybe. Which would probably mean the Euler 'y' portion above is simply 0 or fixed :)

 

Hi Methos5k! Thanks for the input! This has been driving me nuts for the last couple of days!

The logic of Quaternions still eludes me but your suggestion worked perfectly. I left the horizontal rotation of the turret base the same but applied your code to the barrel and viola! It works! Thanks so much. For anyone else who has the same problem here's the code for rotating the tank turret and barrel.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class TurretRotate_SciFiTank : MonoBehaviour
6. {
7.  
8.     //Rotating Key Variables
9.  
10.     public GameObject sciFiTurretBase;  //reference to the turret base of the cannon for side to side movement
11.     public GameObject sciFiBarrel;  //reference to the actual barrel of the cannon for up/down movement
12.  
13.     public string turretLeft; //key to rotate turret to left
14.     public string turretRight; //key to rotate turret to Right
15.     public string turretUp; //key to rotate turret barrel  Up
16.     public string turretDown; //key to rotate turret barrel Down
17.  
18.  
19.     public float barrelRotX;  //float value to plug into Vector3 that will be used w/Quaternion.euler value
20.     public Quaternion barrelRotationFinal;  //quaternion to hold angle of barrel
21.  
22.     public float baseRotY;
23.     public Quaternion baseRotationFinal;
24.  
25.     public float minBarrelRotX;  // min value to use in Mathf.Clamp to limit barrel up/down rotation
26.     public float maxBarrelRotX;  // max value to use in Mathf.Clamp to limit barrel up/down rotation
27.  
28.     public float rotateSpeed;  //rotate speed multiplier for the turret and barrel
29.  
30.  
31.     public Transform sciFiShotPoint;  //position in space to instantiate energy weapon of cannon
32.     //public GameObject sciFiWeapon;  //reference to the weapon prefab
33.     public string shootKey;  //reference to the shoot key of the weapon.
34.  
35.     public GameObject plasmaProjectile;  //projectile of sciFi Tank
36.     //public GameObject plasmaMuzzleFlash;  //muzzle flash effect for plasma
37.     public AudioSource plasmaCannonFire;  //  reference to the audio source containing the cannon fire wav
38.  
39.  
40.     // Use this for initialization
41.     void Start ()
42.     {
43.         rotateSpeed = 30f;
44.     }
45.    
46.     // Update is called once per frame
47.     void Update ()
48.     {
49.  
50.         //limiting barrel up and down values
51.  
52.         if (barrelRotX > maxBarrelRotX)
53.         {
54.             barrelRotX = maxBarrelRotX;
55.         }
56.  
57.         if (barrelRotX < minBarrelRotX)
58.         {
59.             barrelRotX = minBarrelRotX;
60.         }
61.         //...to here
62.  
63.             //CANNON MOVEMENT INPUTS - feeding into the float values
64.         if (Input.GetKey(turretRight))
65.         {
66.             sciFiTurretBase.transform.Rotate (Vector3.up * rotateSpeed * Time.deltaTime);
67.         }
68.  
69.         if (Input.GetKey(turretLeft))
70.         {
71.             sciFiTurretBase.transform.Rotate (Vector3.up * -rotateSpeed * Time.deltaTime);
72.         }
73.  
74.         if (Input.GetKey(turretUp))
75.         {
76.             barrelRotX += Time.deltaTime * rotateSpeed;
77.         }
78.  
79.         if (Input.GetKey(turretDown))
80.         {
81.             barrelRotX += Time.deltaTime * -rotateSpeed;
82.         }
83.  
84.         barrelRotX = Mathf.Clamp (barrelRotX, -45f, 20f);  //clamp the value of barrelRotX
85.         sciFiBarrel.transform.rotation = Quaternion.Euler (barrelRotX, sciFiBarrel.transform.rotation.eulerAngles.y, 0);  //plug into transform.rotation
86.  
87.         //END CANNON CONTROL INPUTS
88.  
89.  
90.  
91.         if (Input.GetKeyDown(shootKey))
92.         {
93.             FirePlasma();
94.         }
95.        
96.     }
97.  
98.     void FirePlasma()
99.     {
100.        
101.         //Instantiate(plasmaProjectile, sciFiShotPoint.position, barrelRotation);
102.         //plasmaCannonFire.Play();
103.     }
104. }

 

Cool, glad it worked for ya

 

I know you already solved your problem, but I think a (perhaps) cleaner solution to your problem is using Mathf.Clamp to clamp your barrel's rotation between 2 predefined angles.

 

Thanks for sharing your final code, it was really helpfull.