Shell Creation

Checked with version: 5.2


Difficulty: Intermediate

Phase 5 teaches you how to create a Shell for the tank, creating a radius for explosion.

Shell Creation

Intermediate Tanks tutorial



Code snippet

using UnityEngine;

public class ShellExplosion : MonoBehaviour
    public LayerMask m_TankMask;                        // Used to filter what the explosion affects, this should be set to "Players".
    public ParticleSystem m_ExplosionParticles;         // Reference to the particles that will play on explosion.
    public AudioSource m_ExplosionAudio;                // Reference to the audio that will play on explosion.
    public float m_MaxDamage = 100f;                    // The amount of damage done if the explosion is centred on a tank.
    public float m_ExplosionForce = 1000f;              // The amount of force added to a tank at the centre of the explosion.
    public float m_MaxLifeTime = 2f;                    // The time in seconds before the shell is removed.
    public float m_ExplosionRadius = 5f;                // The maximum distance away from the explosion tanks can be and are still affected.

    private void Start ()
        // If it isn't destroyed by then, destroy the shell after it's lifetime.
        Destroy (gameObject, m_MaxLifeTime);

    private void OnTriggerEnter (Collider other)
        // Collect all the colliders in a sphere from the shell's current position to a radius of the explosion radius.
        Collider[] colliders = Physics.OverlapSphere (transform.position, m_ExplosionRadius, m_TankMask);

        // Go through all the colliders...
        for (int i = 0; i < colliders.Length; i++)
            // ... and find their rigidbody.
            Rigidbody targetRigidbody = colliders[i].GetComponent<Rigidbody> ();

            // If they don't have a rigidbody, go on to the next collider.
            if (!targetRigidbody)

            // Add an explosion force.
            targetRigidbody.AddExplosionForce (m_ExplosionForce, transform.position, m_ExplosionRadius);

            // Find the TankHealth script associated with the rigidbody.
            TankHealth targetHealth = targetRigidbody.GetComponent<TankHealth> ();

            // If there is no TankHealth script attached to the gameobject, go on to the next collider.
            if (!targetHealth)

            // Calculate the amount of damage the target should take based on it's distance from the shell.
            float damage = CalculateDamage (targetRigidbody.position);

            // Deal this damage to the tank.
            targetHealth.TakeDamage (damage);

        // Unparent the particles from the shell.
        m_ExplosionParticles.transform.parent = null;

        // Play the particle system.

        // Play the explosion sound effect.

        // Once the particles have finished, destroy the gameobject they are on.
        Destroy (m_ExplosionParticles.gameObject, m_ExplosionParticles.duration);

        // Destroy the shell.
        Destroy (gameObject);

    private float CalculateDamage (Vector3 targetPosition)
        // Create a vector from the shell to the target.
        Vector3 explosionToTarget = targetPosition - transform.position;

        // Calculate the distance from the shell to the target.
        float explosionDistance = explosionToTarget.magnitude;

        // Calculate the proportion of the maximum distance (the explosionRadius) the target is away.
        float relativeDistance = (m_ExplosionRadius - explosionDistance) / m_ExplosionRadius;

        // Calculate damage as this proportion of the maximum possible damage.
        float damage = relativeDistance * m_MaxDamage;

        // Make sure that the minimum damage is always 0.
        damage = Mathf.Max (0f, damage);

        return damage;

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