Jetpack Kurt ballstic bullet flight Unity3D

/*
    The following license supersedes all notices in the source code.

    Copyright (c) 2020 Kurt Dekker/PLBM Games All rights reserved.

    http://www.twitter.com/kurtdekker

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

    Redistributions of source code must retain the above copyright notice,
    this list of conditions and the following disclaimer.

    Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.

    Neither the name of the Kurt Dekker/PLBM Games nor the names of its
    contributors may be used to endorse or promote products derived from
    this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
    IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
    TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

// This is part of Jetpack Kurt Space Flight, by Kurt Dekker, available here:
//
// Appstore: https://itunes.apple.com/us/app/jetpack-kurt/id1033348911
// GooglePlay: https://play.google.com/store/apps/details?id=com.plbm.jetpack
//
// External TestFlight link: https://testflight.apple.com/join/wt0HTUba
//
// Youtube playlist: https://www.youtube.com/playlist?list=PLTzufax_A179M51bQgMFDJ7y9Gjp9kOVR
//
// Itch.io: https://kurtdekker.itch.io/jetpack
//
// Simmer.io: https://simmer.io/@kurtdekker/jetpack-kurt


using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class WeaponShot1Controller : MonoBehaviour
{
    const float LaserBoltSpeed = 150.0f;

    const float Gravity = -10.0f;

    Vector3 velocity;

    bool reactive = true;

    public static WeaponShot1Controller Create(
        Vector3 startPosition,
        Vector3 startForward,
        Vector3 playerVelocity)
    {
        var sc = new GameObject( "WeaponShot1Controller.Create();").AddComponent<WeaponShot1Controller>();

        TTL.Attach( sc.gameObject, Random.Range( 3.5f, 4.5f));

        sc.transform.position = startPosition;

        Instantiate<GameObject>( Resources.Load<GameObject>(
            "Prefabs/WeaponShot1Controller_prefab"), sc.transform).GetComponent<ParticleSystem>();

        sc.velocity = playerVelocity + startForward.normalized * LaserBoltSpeed;

        sc.UpdateMovement();

        return sc;
    }

    void UpdateMovement()
    {
        velocity += Vector3.up * Gravity * Time.deltaTime;

        Vector3 movement = velocity * Time.deltaTime;

        Vector3 newPosition = transform.position + movement;

        // possible outcomes from impact/contact with a collider:
        //
        //  - don't ricochet off a damage-taker (this might not be necessary)
        //
        //  - case of ricochet:
        //      - choose random speed attenuation
        //      - deflect according to normal
        //      - deflect a bit more randomly
        //      - if below a certain amount, become unreactive
        //
        //  - case of impact and finish:
        //      - destroy
        //
        // If reactive, leave a little splash cloud of particles
        //
        Ray ray = new Ray( transform.position, velocity);
        RaycastHit rch;
        if (Physics.Raycast( ray, out rch, movement.magnitude, ~(1 << MyLayers.i_Player)))
        {
            bool CanRicochet = reactive;

            newPosition = rch.point;

            var da = rch.collider.GetComponent<ICombatDamageable>();
            if (da != null)
            {
                da.TakeDamage( 1.0f);

                CanRicochet = false;

                STATE.MissionShotsHit++;
            }

            if (reactive)
            {
                SpaceFlightShotImpact.Create( newPosition, rch.normal);
            }

            // chance of carom/ricochet?
            if (CanRicochet)
            {
                if (Random.Range( 0, 6) == 0)
                {
                    float attenuate1 = Random.Range( 0.05f, 0.6f);
                    float attenuate2 = Mathf.Min( attenuate1, Random.Range( 0.05f, 0.6f));
                    float attenuate3 = Mathf.Min( attenuate2, Random.Range( 0.05f, 0.6f));

                    velocity.x *= attenuate3;
                    velocity.y *= attenuate1;
                    velocity.z *= attenuate3;

                    var impactSpeed = Vector3.Dot( velocity, rch.normal);

                    var reflect = rch.normal * impactSpeed * Random.Range( 1.8f, 3.0f);

                    velocity -= reflect;

                    // chance of becoming unreactive: we no longer make ricochet splash visuals
                    if (velocity.magnitude < 30)
                    {
                        // and a sub-chance of just going away when we're this slow
                        if (Random.Range( 0, 3) > 0)
                        {
                            reactive = false;
                        }
                    }
                }
            }
            else
            {
                Destroy( gameObject);
            }
        }

        Vector3 oldPosition = transform.position;

        transform.position = newPosition;
    }

    void Update ()
    {
        UpdateMovement();
    }
}