[unity3d] blood bar (HP)

1 Demand fulfillment

         human-computer interaction Input  It realizes the control of tank movement through the keyboard , Control the tank to launch shells through the mouse , On this basis, this paper will , Increase blood bar （HP） function . After the shell hit ,HP The value will decrease , Therefore, it needs to be applied to   Rigid body components Rigidbody  and   Impactor assembly Collider; When attacking the enemy from different angles , The enemy's blood bar is always facing the camera , So we need to use   The camera follows ; Blood bar pass Image Show , So we need to use  UGUI And Image; The player's blood bar is always displayed in the upper left corner of the screen , So we need to use   Anchor point .

        1） Demand fulfillment

• Front and back arrow keys or W, S Key to control the player to move forward or backward ;
• Left and right arrow keys or A, D Key to control the player to turn left and right ;
• The left mouse button or the space bar controls the player to fire shells ;
• The player's blood bar is displayed in the upper left corner of the screen ;
• The position of the camera above the back of the player , Always follow the player , Look directly in front of the player ;
• When players move , The enemy turns to the player , When the angle away from the player is less than 5° when , Fire a shell ;
• The enemy's blood bar is displayed above it , And always look at the camera .

        2） It's about the technology stack

• Transform Components
• human-computer interaction
• Rigid body components Rigidbody
• Impactor assembly Collider
• The camera follows
• UGUI And Image
• Canvas Rendering mode and anchor

2 The game object

        1） Game interface

        2） GameObject hierarchy

        3 Transform Component parameters

        1） The player  Transform Component parameters

         Add ：Player Game object added rigid body components , And modify it Mass = 100,Drag = 1,AngularDrag = 0.1,Freeze Rotation The admission X and Z. 

        2） The player HP RectTransform Component parameters

        Add ：  The player PlayerHP Of Canvas  The rendering mode is  Screen Space - Overlay,Health Of ImageType Set to Filled,Fill Method Set to Horizontal.

        3） The enemy  Transform Component parameters

         Add ：Enemy Game object added rigid body components , And modify it Mass = 100,Drag = 0.5,AngularDrag = 0.1,Freeze Rotation The admission X and Z.  

        4） The enemy HP RectTransform Component parameters

         Add ： The enemy  HP Of Canvas  The rendering mode is  World Space,Health Of ImageType Set to Filled,Fill Method Set to Horizontal.

        5） Ground and shells  Transform Component parameters

        Add ： The shell is dragged as a preset body to Assets/Resources/Prefabs Under the table of contents , And added rigid body components .

3 Script components

        1）CameraController

        CameraController.cs

using UnityEngine;
 
public class CameraController : MonoBehaviour {
	private Transform player; //  The player 
	private Vector3 relaPlayerPos; //  The position of the camera in the player's coordinate system 
	private float targetDistance = 15f; //  The camera looks at the position in front of the player 
 
	private void Start() {
		relaPlayerPos = new Vector3(0, 4, -8);
		player = GameObject.Find("Player/Top").transform;
	}
 
	private void LateUpdate() {
		CompCameraPos();
	}

	private void CompCameraPos() { //  Calculate camera coordinates 
		Vector3 target = player.position + player.forward * targetDistance;
		transform.position = transformVecter(relaPlayerPos, player.position, player.right, player.up, player.forward);
		transform.rotation = Quaternion.LookRotation(target - transform.position);
	}

	//  Seeking for origin Origin , locX, locY, locZ  Is the vector in the local coordinate system of the coordinate axis  vec  The corresponding vector in the world coordinate system 
	private Vector3 transformVecter(Vector3 vec, Vector3 origin, Vector3 locX,  Vector3 locY,  Vector3 locZ) {
		return vec.x * locX + vec.y * locY + vec.z * locZ + origin;
	}
}

        explain ： CameraController The script component is hung on MainCamera On the object of the game .

        2）PlayerController

        PlayerController.cs

using System;
using UnityEngine;

public class PlayerController : MonoBehaviour {
	private Transform firePoint; //  Firing point 
	private GameObject bulletPrefab; //  Shell preset 
	private float tankMoveSpeed = 4f; //  Tank moving speed 
	private float tankRotateSpeed = 2f; //  The turning speed of the tank 
	private float fireWaitTime = float.MaxValue; //  The waiting time since the last firing 
	private float bulletCoolTime = 0.15f; //  Shell cooling time 

	private void Start() {
		firePoint = transform.Find("Top/Gun/FirePoint");
		bulletPrefab = (GameObject) Resources.Load("Prefabs/Bullet");
	}

	private void Update() {
		fireWaitTime += Time.deltaTime;
		float hor = Input.GetAxis("Horizontal");
        float ver = Input.GetAxis("Vertical");
		Move(hor, ver);
		if (Input.GetMouseButtonDown(0) || Input.GetKeyDown(KeyCode.Space)) {
			Fire();
		}
	}

	private void Move(float hor, float ver) { //  Tank movement 
		if (Math.Abs(hor) > 0.1f || Math.Abs(ver) > 0.1f) {
			GetComponent<Rigidbody>().velocity = transform.forward * tankMoveSpeed * ver;
			GetComponent<Rigidbody>().angularVelocity = Vector3.up * tankRotateSpeed * hor;
		}
	}

	private void Fire() { //  fire 
		if (fireWaitTime > bulletCoolTime) {
			BulletInfo bulletInfo = new BulletInfo("PlayerBullet", Color.red, transform.forward, 10f, 15f);
			GameObject bullet = Instantiate(bulletPrefab, firePoint.position, Quaternion.identity);
			bullet.AddComponent<BulletController>().SetBulletInfo(bulletInfo);
			fireWaitTime = 0f;
		}
	}
}

        explain ： PlayerController  The script component is hung on Player On the object of the game . 

        3）EnemyController

        EnemyController.cs

using UnityEngine;
using UnityEngine.UI;

public class EnemyController : MonoBehaviour {
	private Transform target; //  The goal is 
	private Transform top; //  Gun head 
	private Transform firePoint; //  Firing point 
	private Transform hp; //  Blood strip 
	private GameObject bulletPrefab; //  Shell preset 
	private float rotateSpeed = 0.4f; //  The turning speed of the tank 
	private float fireWaitTime = float.MaxValue; //  The waiting time since the last firing 
	private float bulletCoolTime = 1f; //  Shell cooling time 

	private void Start () {
		target = GameObject.Find("Player/Top").transform;
		top = transform.Find("Top");
		firePoint = transform.Find("Top/Gun/FirePoint");
		hp = transform.Find("HP");
		bulletPrefab = (GameObject) Resources.Load("Prefabs/Bullet");
	}

	private void Update () {
		fireWaitTime += Time.deltaTime;
		LookAtTarget();
		float angle = Vector3.Angle(target.position - top.position, top.forward);
		if (LookAtTarget()) {
			Fire();
		}
		HPLookAtCamera();
	}

	private bool LookAtTarget() {
		Vector3 dir = target.position - top.position;
		float angle = Vector3.Angle(dir, top.forward);
		if (angle > 5) {
			int axis = Vector3.Dot(Vector3.Cross(dir, top.forward), Vector3.up) > 0 ? -1 : 1;
			GetComponent<Rigidbody>().angularVelocity = axis * Vector3.up * rotateSpeed;
			return false;
		}
		GetComponent<Rigidbody>().angularVelocity = Vector3.zero;
		return true;
	}

	private void HPLookAtCamera() {
		Vector3 cameraPos = Camera.main.transform.position;
		Vector3 target = new Vector3(cameraPos.x, hp.position.y, cameraPos.z);
		hp.LookAt(target);
	}

	private void Fire() {
		if (fireWaitTime > bulletCoolTime) {
			BulletInfo bulletInfo = new BulletInfo("EnemyBullet", Color.yellow, top.forward, 5f, 10f);
			GameObject bullet = Instantiate(bulletPrefab, firePoint.position, Quaternion.identity); //  Create shells from presets 
			bullet.AddComponent<BulletController>().SetBulletInfo(bulletInfo);
			fireWaitTime = 0;
		}
	}
}

        explain ： EnemyController  The script component is hung on Enemy On the object of the game .  

        4）BulletController

        BulletController.cs

using UnityEngine;
using UnityEngine.UI;

public class BulletController : MonoBehaviour {
	private BulletInfo bulletInfo; //  Shell information 
	private volatile bool isDying = false;

	private void Start () {
		gameObject.name = bulletInfo.name;
		GetComponent<MeshRenderer>().material.color = bulletInfo.color;
		float lifeTime = bulletInfo.fireRange / bulletInfo.speed; //  Survival time 
		Destroy(gameObject, lifeTime);
	}

	private void Update () {
		transform.GetComponent<Rigidbody>().velocity = bulletInfo.flyDir * bulletInfo.speed;
	}

	private void OnCollisionEnter(Collision other) {
		if (isDying) {
			return;
		}
		if (IsHitEnemy(gameObject.name, other.gameObject.name)) {
			other.transform.Find("HP/Health").GetComponent<Image>().fillAmount -= 0.1f;
			isDying = true;
			Destroy(gameObject, 0.1f);
		} else if (IsHitPlayer(gameObject.name, other.gameObject.name)) {
			GameObject.Find("PlayerHP/Panel/Health").GetComponent<Image>().fillAmount -= 0.1f;
			isDying = true;
			Destroy(gameObject, 0.1f);
		}
	}

	public void SetBulletInfo(BulletInfo bulletInfo) {
		this.bulletInfo = bulletInfo;
	}

	private bool IsHitEnemy(string name, string otherName) { //  Shoot the enemy 
		return name.Equals("PlayerBullet") && otherName.Equals("Enemy");
	}

	private bool IsHitPlayer(string name, string otherName) { //  Shoot players 
		return name.Equals("EnemyBullet") && otherName.Equals("Player");
	}
}

        explain ： BulletController The script component is hung on Bullet On the object of the game （ Dynamic addition in the code ）.   

        5）BulletInfo

        BulletInfo.cs

using UnityEngine;

public class BulletInfo {
	public string name; //  Shell name 
	public Color color; //  Shell color 
	public Vector3 flyDir; //  The direction in which the shell flew 
	public float speed; //  Projectile speed 
	public float fireRange; //  Shell range 

	public BulletInfo(string name, Color color, Vector3 flyDir, float speed, float fireRange) {
		this.name = name;
		this.color = color;
		this.flyDir = flyDir;
		this.speed = speed;
		this.fireRange = fireRange;
	}
}

4 Running effect