Viewport.java

package com.osroyale.game.world.entity.mob;
 
import com.osroyale.game.world.entity.mob.npc.Npc;
import com.osroyale.game.world.entity.mob.player.Player;
 
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

 
public final class Viewport {

    public static final int ADD_THRESHOLD = 15;

    public static final int CAPACITY = 100;

    public static final int VIEW_DISTANCE = 15;

    private final List<Player> playersInViewport = new LinkedList<>();

    private final List<Npc> npcsInViewport = new LinkedList<>();

    private final AtomicInteger playerViewingDistance = new AtomicInteger(VIEW_DISTANCE);

    private final AtomicInteger npcViewingDistance = new AtomicInteger(VIEW_DISTANCE);

    private final Player player;
 
    public Viewport(Player player) {
        this.player = player;
    }

    public boolean add(Mob other) {
        if (!canAdd(other)) {
            return false;
        }
 
        if (other.isPlayer()) {
            playersInViewport.add(other.getPlayer());
            other.updateFlags.add(UpdateFlag.APPEARANCE);
        } else if (other.isNpc()) {
            npcsInViewport.add(other.getNpc());
            other.updateFlags.add(UpdateFlag.FACE_COORDINATE); // doing this for players for some reason crashes the players client
        }
        return true;
    }

    private boolean canAdd(Mob other) {
        if (shouldRemove(other)) {
            return false;
        }
 
        if (other.isPlayer()) {
            Player player = other.getPlayer();
            return !playersInViewport.contains(player);
        } else if (other.isNpc()) {
            Npc npc = other.getNpc();
            return !npcsInViewport.contains(npc);
        }
 
        return false;
    }

    public boolean shouldRemove(Mob other) {
        boolean sameEntity = player == other;
        boolean notValid = !other.isValid();
        boolean notVisible = !other.isVisible();
        boolean notSameInstance = player.instance != other.instance;
        boolean notInDistance = !player.getPosition().isWithinDistance(other.getPosition().copy(), other.isPlayer() ? player.viewport.getPlayerViewingDistance() : player.viewport.getNpcViewingDistance());
        boolean positionChanged = other.positionChange || other.teleportRegion;
        boolean regionChanged = other.regionChange && other.teleporting;
        return sameEntity || notValid || notVisible || notSameInstance || notInDistance || regionChanged || positionChanged;
    }

    public void calculateViewingDistance() {
        if (playersInViewport.size() >= Viewport.CAPACITY) {
            if (playerViewingDistance.decrementAndGet() < 1) {
                playerViewingDistance.set(1);
            }
        } else {
            if (playerViewingDistance.incrementAndGet() > VIEW_DISTANCE) {
                playerViewingDistance.set(VIEW_DISTANCE);
            }
        }
 
        if (npcsInViewport.size() >= Viewport.CAPACITY) {
            if (npcViewingDistance.decrementAndGet() < 1) {
                npcViewingDistance.set(1);
            }
        } else {
            if (npcViewingDistance.incrementAndGet() > VIEW_DISTANCE) {
                npcViewingDistance.set(VIEW_DISTANCE);
            }
        }
    }

    public List<Player> getPlayersInViewport() {
        return playersInViewport;
    }

    public List<Npc> getNpcsInViewport() {
        return npcsInViewport;
    }

    public int getPlayerViewingDistance() {
        return playerViewingDistance.get();
    }

    public int getNpcViewingDistance() {
        return npcViewingDistance.get();
    }
 
}