ForgottenWawiTech/Content/Projectiles/Transcendent/TranscendentBladeShard.cs

using Microsoft.Xna.Framework;
using System;
using Terraria;
using Terraria.ID;
using Terraria.ModLoader;

namespace ForgottenWawiTech.Content.Projectiles.Transcendent
{
    public class TranscendentBladeShard : ModProjectile
    {
        public override void SetStaticDefaults()
        {
            ProjectileID.Sets.TrailCacheLength[Type] = 12;
            ProjectileID.Sets.TrailingMode[Type] = 2;
        }

        public override string Texture => "ForgottenWawiTech/Assets/PlaceholderProj";

        public override void SetDefaults()
        {
            Projectile.width = 18;
            Projectile.height = 18;
            Projectile.friendly = true;
            Projectile.hostile = false;
            Projectile.penetrate = 4;
            Projectile.timeLeft = 180;
            Projectile.alpha = 40;
            Projectile.tileCollide = false;
            Projectile.extraUpdates = 1;
            Projectile.DamageType = DamageClass.Melee;
            Projectile.ignoreWater = true;
        }

        public override void AI()
        {
            Projectile.rotation += 0.4f * Projectile.direction;
            Lighting.AddLight(Projectile.Center, 0.35f, 0.25f, 0.55f);

            if (Projectile.localAI[0] == 0f)
            {
                Projectile.localAI[0] = 1f;
                Projectile.velocity *= 1.1f;
            }

            NPC target = FindTarget(720f);
            if (target != null)
            {
                float homingStrength = 0.18f;
                float desiredSpeed = 20f;
                Vector2 desiredVelocity = Projectile.DirectionTo(target.Center) * desiredSpeed;
                Projectile.velocity = Vector2.Lerp(Projectile.velocity, desiredVelocity, homingStrength);
            }

            if (Main.rand.NextBool(3))
            {
                int dustIndex = Dust.NewDust(Projectile.position, Projectile.width, Projectile.height, DustID.RainbowTorch, 0f, 0f, 150, default, 1.2f);
                Dust dust = Main.dust[dustIndex];
                dust.noGravity = true;
                dust.velocity = Projectile.velocity * 0.3f;
            }
        }

        private NPC FindTarget(float maxDetectDistance)
        {
            NPC selected = null;
            float sqr = maxDetectDistance * maxDetectDistance;
            for (int i = 0; i < Main.maxNPCs; i++)
            {
                NPC npc = Main.npc[i];
                if (npc.CanBeChasedBy())
                {
                    float dist = Vector2.DistanceSquared(npc.Center, Projectile.Center);
                    if (dist < sqr)
                    {
                        sqr = dist;
                        selected = npc;
                    }
                }
            }

            return selected;
        }

        public override void OnHitNPC(NPC target, NPC.HitInfo hit, int damageDone)
        {
            target.AddBuff(BuffID.Daybreak, 300);
            target.AddBuff(ModContent.BuffType<Content.Buffs.Debuffs.TypeNull>(), 300);
        }
    }
}