npc.go

package npc

import (
	"github.com/df-mc/dragonfly/server/player"
	"github.com/df-mc/dragonfly/server/world"
	"github.com/go-gl/mathgl/mgl64"
	"time"
)

// HandlerFunc may be passed to Create to handle a *player.Player attacking an NPC.
type HandlerFunc func(p *player.Player)

// Create creates a new NPC with the Settings passed. A world.Loader is spawned in the background which follows the
// NPC to prevent it from despawning. Create panics if the *world.Tx passed is nil.
// The HandlerFunc passed handles a player interacting with the NPC. Nil may be passed to avoid calling any function
// when the entity is interacted with.
// Create returns the *player.Player created. This entity has been added to the tx world passed. It may be removed from
// the world like any other entity by calling (*player.Player).Close.
func Create(s Settings, tx *world.Tx, f HandlerFunc) *player.Player {
	if tx == nil {
		panic("tx passed to npc.create must not be nil")
	}
	if f == nil {
		f = func(*player.Player) {}
	}

	opts := world.EntitySpawnOpts{
		Position: s.Position,
	}

	ent := opts.New(player.Type, player.Config{Name: s.Name, Position: s.Position, Skin: s.Skin})
	l := world.NewLoader(1, tx.World(), world.NopViewer{})

	e := tx.AddEntity(ent)
	npc := e.(*player.Player)

	npc.Move(mgl64.Vec3{}, s.Yaw, s.Pitch)
	npc.SetScale(s.Scale)
	npc.SetHeldItems(s.MainHand, s.OffHand)
	npc.Armour().Set(s.Helmet, s.Chestplate, s.Leggings, s.Boots)
	if s.Immobile {
		npc.SetImmobile()
	}

	h := &handler{f: f, l: l, vulnerable: s.Vulnerable}
	npc.Handle(h)

	h.syncPosition(tx, s.Position)

	go syncWorld(ent, l)
	return npc
}

// syncWorld periodically synchronises the world of the world.Loader passed with a player.Player's world. It stops doing
// so once the world returned by (*player.Player).World is nil.
func syncWorld(npc *world.EntityHandle, l *world.Loader) {
	t := time.NewTicker(time.Second / 20)
	defer t.Stop()

	for range t.C {
		if !npc.ExecWorld(func(tx *world.Tx, e world.Entity) {
			if w := tx.World(); w != l.World() {
				l.ChangeWorld(tx, w)
			}
		}) {
			return
		}
	}
}