minecraft-src/net/minecraft/world/entity/projectile/EyeOfEnder.java

package net.minecraft.world.entity.projectile;

import net.minecraft.core.particles.ParticleTypes;
import net.minecraft.network.syncher.EntityDataAccessor;
import net.minecraft.network.syncher.EntityDataSerializers;
import net.minecraft.network.syncher.SynchedEntityData;
import net.minecraft.server.level.ServerLevel;
import net.minecraft.sounds.SoundEvents;
import net.minecraft.util.Mth;
import net.minecraft.world.damagesource.DamageSource;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.item.ItemEntity;
import net.minecraft.world.item.ItemStack;
import net.minecraft.world.item.Items;
import net.minecraft.world.level.Level;
import net.minecraft.world.level.storage.ValueInput;
import net.minecraft.world.level.storage.ValueOutput;
import net.minecraft.world.phys.Vec3;
import org.jetbrains.annotations.Nullable;

public class EyeOfEnder extends Entity implements ItemSupplier {
	private static final float MIN_CAMERA_DISTANCE_SQUARED = 12.25F;
	private static final float TOO_FAR_SIGNAL_HEIGHT = 8.0F;
	private static final float TOO_FAR_DISTANCE = 12.0F;
	private static final EntityDataAccessor<ItemStack> DATA_ITEM_STACK = SynchedEntityData.defineId(EyeOfEnder.class, EntityDataSerializers.ITEM_STACK);
	@Nullable
	private Vec3 target;
	private int life;
	private boolean surviveAfterDeath;

	public EyeOfEnder(EntityType<? extends EyeOfEnder> entityType, Level level) {
		super(entityType, level);
	}

	public EyeOfEnder(Level level, double x, double y, double z) {
		this(EntityType.EYE_OF_ENDER, level);
		this.setPos(x, y, z);
	}

	public void setItem(ItemStack stack) {
		if (stack.isEmpty()) {
			this.getEntityData().set(DATA_ITEM_STACK, this.getDefaultItem());
		} else {
			this.getEntityData().set(DATA_ITEM_STACK, stack.copyWithCount(1));
		}
	}

	@Override
	public ItemStack getItem() {
		return this.getEntityData().get(DATA_ITEM_STACK);
	}

	@Override
	protected void defineSynchedData(SynchedEntityData.Builder builder) {
		builder.define(DATA_ITEM_STACK, this.getDefaultItem());
	}

	@Override
	public boolean shouldRenderAtSqrDistance(double distance) {
		if (this.tickCount < 2 && distance < 12.25) {
			return false;
		} else {
			double d = this.getBoundingBox().getSize() * 4.0;
			if (Double.isNaN(d)) {
				d = 4.0;
			}

			d *= 64.0;
			return distance < d * d;
		}
	}

	public void signalTo(Vec3 pos) {
		Vec3 vec3 = pos.subtract(this.position());
		double d = vec3.horizontalDistance();
		if (d > 12.0) {
			this.target = this.position().add(vec3.x / d * 12.0, 8.0, vec3.z / d * 12.0);
		} else {
			this.target = pos;
		}

		this.life = 0;
		this.surviveAfterDeath = this.random.nextInt(5) > 0;
	}

	@Override
	public void tick() {
		super.tick();
		Vec3 vec3 = this.position().add(this.getDeltaMovement());
		if (!this.level().isClientSide() && this.target != null) {
			this.setDeltaMovement(updateDeltaMovement(this.getDeltaMovement(), vec3, this.target));
		}

		if (this.level().isClientSide()) {
			Vec3 vec32 = vec3.subtract(this.getDeltaMovement().scale(0.25));
			this.spawnParticles(vec32, this.getDeltaMovement());
		}

		this.setPos(vec3);
		if (!this.level().isClientSide()) {
			this.life++;
			if (this.life > 80 && !this.level().isClientSide) {
				this.playSound(SoundEvents.ENDER_EYE_DEATH, 1.0F, 1.0F);
				this.discard();
				if (this.surviveAfterDeath) {
					this.level().addFreshEntity(new ItemEntity(this.level(), this.getX(), this.getY(), this.getZ(), this.getItem()));
				} else {
					this.level().levelEvent(2003, this.blockPosition(), 0);
				}
			}
		}
	}

	private void spawnParticles(Vec3 pos, Vec3 deltaMovement) {
		if (this.isInWater()) {
			for (int i = 0; i < 4; i++) {
				this.level().addParticle(ParticleTypes.BUBBLE, pos.x, pos.y, pos.z, deltaMovement.x, deltaMovement.y, deltaMovement.z);
			}
		} else {
			this.level()
				.addParticle(
					ParticleTypes.PORTAL,
					pos.x + this.random.nextDouble() * 0.6 - 0.3,
					pos.y - 0.5,
					pos.z + this.random.nextDouble() * 0.6 - 0.3,
					deltaMovement.x,
					deltaMovement.y,
					deltaMovement.z
				);
		}
	}

	private static Vec3 updateDeltaMovement(Vec3 deltaMovement, Vec3 pos, Vec3 target) {
		Vec3 vec3 = new Vec3(target.x - pos.x, 0.0, target.z - pos.z);
		double d = vec3.length();
		double e = Mth.lerp(0.0025, deltaMovement.horizontalDistance(), d);
		double f = deltaMovement.y;
		if (d < 1.0) {
			e *= 0.8;
			f *= 0.8;
		}

		double g = pos.y - deltaMovement.y < target.y ? 1.0 : -1.0;
		return vec3.scale(e / d).add(0.0, f + (g - f) * 0.015, 0.0);
	}

	@Override
	protected void addAdditionalSaveData(ValueOutput output) {
		output.store("Item", ItemStack.CODEC, this.getItem());
	}

	@Override
	protected void readAdditionalSaveData(ValueInput input) {
		this.setItem((ItemStack)input.read("Item", ItemStack.CODEC).orElse(this.getDefaultItem()));
	}

	private ItemStack getDefaultItem() {
		return new ItemStack(Items.ENDER_EYE);
	}

	@Override
	public float getLightLevelDependentMagicValue() {
		return 1.0F;
	}

	@Override
	public boolean isAttackable() {
		return false;
	}

	@Override
	public boolean hurtServer(ServerLevel level, DamageSource damageSource, float amount) {
		return false;
	}
}