Added a fall manager for entities

server/entity/fall.go

@@ -0,0 +1,91 @@
+package entity
+
+import (
+	"github.com/df-mc/atomic"
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"github.com/df-mc/dragonfly/server/entity/damage"
+	"github.com/df-mc/dragonfly/server/entity/effect"
+	"github.com/df-mc/dragonfly/server/world"
+	"math"
+)
+
+// FallManager handles entities that can fall.
+type FallManager struct {
+	e            fallEntity
+	fallDistance atomic.Float64
+}
+
+// fallEntity is an entity that can fall.
+type fallEntity interface {
+	world.Entity
+	OnGround() bool
+}
+
+// entityLander represents a block that reacts to an entity landing on it after falling.
+type entityLander interface {
+	// EntityLand is called when an entity lands on the block.
+	EntityLand(pos cube.Pos, w *world.World, e world.Entity)
+}
+
+// NewFallManager returns a new fall manager.
+func NewFallManager(e fallEntity) *FallManager {
+	return &FallManager{e: e}
+}
+
+// SetFallDistance sets the fall distance of the entity.
+func (f *FallManager) SetFallDistance(distance float64) {
+	f.fallDistance.Store(distance)
+}
+
+// FallDistance returns the entity's fall distance.
+func (f *FallManager) FallDistance() float64 {
+	return f.fallDistance.Load()
+}
+
+// ResetFallDistance resets the player's fall distance.
+func (f *FallManager) ResetFallDistance() {
+	f.fallDistance.Store(0)
+}
+
+// UpdateFallState is called to update the entities falling state.
+func (f *FallManager) UpdateFallState(distanceThisTick float64, checkOnGround bool) {
+	fallDistance := f.fallDistance.Load()
+	if checkOnGround && f.e.OnGround() {
+		if fallDistance > 0 {
+			f.fall(fallDistance)
+			f.ResetFallDistance()
+		}
+	} else if distanceThisTick < fallDistance {
+		f.fallDistance.Sub(distanceThisTick)
+	} else {
+		f.ResetFallDistance()
+	}
+}
+
+// fall is called when a falling entity hits the ground. It handles the landing, calling EntityLand if needed,
+// and applying fall damage to living entities.
+func (f *FallManager) fall(distance float64) {
+	var (
+		w   = f.e.World()
+		pos = cube.PosFromVec3(f.e.Position())
+		b   = w.Block(pos)
+		dmg = distance - 3
+	)
+	if len(b.Model().BBox(pos, w)) == 0 {
+		pos = pos.Sub(cube.Pos{0, 1})
+		b = w.Block(pos)
+	}
+	if h, ok := b.(entityLander); ok {
+		h.EntityLand(pos, w, f.e)
+	}
+
+	if p, ok := f.e.(Living); ok {
+		if boost, ok := p.Effect(effect.JumpBoost{}); ok {
+			dmg -= float64(boost.Level())
+		}
+		if dmg < 0.5 {
+			return
+		}
+		p.Hurt(math.Ceil(dmg), damage.SourceFall{})
+	}
+}

server/entity/falling_block.go

@@ -2,7 +2,6 @@ package entity
 
 import (
 	"fmt"
-	"github.com/df-mc/atomic"
 	"github.com/df-mc/dragonfly/server/block/cube"
 	"github.com/df-mc/dragonfly/server/entity/damage"
 	"github.com/df-mc/dragonfly/server/internal/nbtconv"
@@ -17,8 +16,8 @@ import (
 type FallingBlock struct {
 	transform
 
-	block        world.Block
-	fallDistance atomic.Float64
+	block world.Block
+	fall  *FallManager
 
 	c *MovementComputer
 }
@@ -33,6 +32,7 @@ func NewFallingBlock(block world.Block, pos mgl64.Vec3) *FallingBlock {
 			DragBeforeGravity: true,
 		},
 	}
+	b.fall = NewFallManager(b)
 	b.transform = newTransform(b, pos)
 	return b
 }
@@ -59,7 +59,7 @@ func (f *FallingBlock) Block() world.Block {
 
 // FallDistance ...
 func (f *FallingBlock) FallDistance() float64 {
-	return f.fallDistance.Load()
+	return f.fall.FallDistance()
 }
 
 // damager ...
@@ -77,6 +77,11 @@ type landable interface {
 	Landed(w *world.World, pos cube.Pos)
 }
 
+// OnGround ...
+func (f *FallingBlock) OnGround() bool {
+	return f.c.OnGround()
+}
+
 // Tick ...
 func (f *FallingBlock) Tick(w *world.World, _ int64) {
 	f.mu.Lock()
@@ -86,12 +91,7 @@ func (f *FallingBlock) Tick(w *world.World, _ int64) {
 
 	m.Send()
 
-	distThisTick := f.vel.Y()
-	if distThisTick < f.fallDistance.Load() {
-		f.fallDistance.Sub(distThisTick)
-	} else {
-		f.fallDistance.Store(0)
-	}
+	f.fall.UpdateFallState(f.vel.Y(), false)
 
 	pos := cube.PosFromVec3(m.pos)
 	if pos[1] < w.Range()[0] {
@@ -101,7 +101,7 @@ func (f *FallingBlock) Tick(w *world.World, _ int64) {
 	if a, ok := f.block.(Solidifiable); (ok && a.Solidifies(pos, w)) || f.c.OnGround() {
 		if d, ok := f.block.(damager); ok {
 			damagePerBlock, maxDamage := d.Damage()
-			if dist := math.Ceil(f.fallDistance.Load() - 1.0); dist > 0 {
+			if dist := math.Ceil(f.FallDistance() - 1.0); dist > 0 {
 				force := math.Min(math.Floor(dist*damagePerBlock), maxDamage)
 				for _, e := range w.EntitiesWithin(f.BBox().Translate(m.pos).Grow(0.05), f.ignores) {
 					e.(Living).Hurt(force, damage.SourceBlock{Block: f.block})
@@ -137,7 +137,7 @@ func (f *FallingBlock) DecodeNBT(data map[string]any) any {
 	}
 	n := NewFallingBlock(b, nbtconv.MapVec3(data, "Pos"))
 	n.SetVelocity(nbtconv.MapVec3(data, "Motion"))
-	n.fallDistance.Store(nbtconv.Map[float64](data, "FallDistance"))
+	n.fall.SetFallDistance(nbtconv.Map[float64](data, "FallDistance"))
 	return n
 }
 

server/entity/living.go

@@ -45,6 +45,9 @@ type Living interface {
 	AddEffect(e effect.Effect)
 	// RemoveEffect removes any effect that might currently be active on the entity.
 	RemoveEffect(e effect.Type)
+	// Effect returns the effect instance and true if the Player has the effect. If not found, it will return an empty
+	// effect instance and false.
+	Effect(e effect.Type) (effect.Effect, bool)
 	// Effects returns any effect currently applied to the entity. The returned effects are guaranteed not to have
 	// expired when returned.
 	Effects() []effect.Effect

server/player/player.go

@@ -67,8 +67,7 @@ type Player struct {
 	invisible, immobile, onGround, usingItem atomic.Bool
 	usingSince atomic.Int64
 
-	fireTicks    atomic.Int64
-	fallDistance atomic.Float64
+	fireTicks atomic.Int64
 
 	breathing         bool
 	airSupplyTicks    atomic.Int64
@@ -83,6 +82,7 @@ type Player struct {
 	health     *entity.HealthManager
 	experience *entity.ExperienceManager
 	effects    *entity.EffectManager
+	fall       *entity.FallManager
 
 	lastXPPickup atomic.Value[time.Time]
 	immunity     atomic.Value[time.Time]
@@ -116,6 +116,7 @@ func New(name string, skin skin.Skin, pos mgl64.Vec3) *Player {
 		health:            entity.NewHealthManager(),
 		experience:        entity.NewExperienceManager(),
 		effects:           entity.NewEffectManager(),
+		fall:              entity.NewFallManager(p),
 		gameMode:          *atomic.NewValue[world.GameMode](world.GameModeSurvival),
 		h:                 *atomic.NewValue[Handler](NopHandler{}),
 		name:              name,
@@ -262,12 +263,12 @@ func (p *Player) SendToast(title, message string) {
 
 // ResetFallDistance resets the player's fall distance.
 func (p *Player) ResetFallDistance() {
-	p.fallDistance.Store(0)
+	p.fall.ResetFallDistance()
 }
 
 // FallDistance returns the player's fall distance.
 func (p *Player) FallDistance() float64 {
-	return p.fallDistance.Load()
+	return p.fall.FallDistance()
 }
 
 // SendTitle sends a title to the player. The title may be configured to change the duration it is displayed
@@ -473,45 +474,6 @@ func (p *Player) Heal(health float64, source healing.Source) {
 	p.addHealth(health)
 }
 
-// updateFallState is called to update the entities falling state.
-func (p *Player) updateFallState(distanceThisTick float64) {
-	fallDistance := p.fallDistance.Load()
-	if p.OnGround() {
-		if fallDistance > 0 {
-			p.fall(fallDistance)
-			p.ResetFallDistance()
-		}
-	} else if distanceThisTick < fallDistance {
-		p.fallDistance.Sub(distanceThisTick)
-	} else {
-		p.ResetFallDistance()
-	}
-}
-
-// fall is called when a falling entity hits the ground.
-func (p *Player) fall(distance float64) {
-	var (
-		w   = p.World()
-		pos = cube.PosFromVec3(p.Position())
-		b   = w.Block(pos)
-	)
-	if len(b.Model().BBox(pos, w)) == 0 {
-		pos = pos.Sub(cube.Pos{0, 1})
-		b = w.Block(pos)
-	}
-	if h, ok := b.(block.EntityLander); ok {
-		h.EntityLand(pos, w, p, &distance)
-	}
-	dmg := distance - 3
-	if boost, ok := p.Effect(effect.JumpBoost{}); ok {
-		dmg -= float64(boost.Level())
-	}
-	if dmg < 0.5 {
-		return
-	}
-	p.Hurt(math.Ceil(dmg), damage.SourceFall{})
-}
-
 // Hurt hurts the player for a given amount of damage. The source passed represents the cause of the damage,
 // for example damage.SourceEntityAttack if the player is attacked by another entity.
 // If the final damage exceeds the health that the player currently has, the player is killed and will have to
@@ -1899,7 +1861,7 @@ func (p *Player) Move(deltaPos mgl64.Vec3, deltaYaw, deltaPitch float64) {
 	p.checkBlockCollisions(w)
 	p.onGround.Store(p.checkOnGround(w))
 
-	p.updateFallState(deltaPos[1])
+	p.fall.UpdateFallState(deltaPos[1], true)
 
 	// The vertical axis isn't relevant for calculation of exhaustion points.
 	deltaPos[1] = 0
@@ -2592,7 +2554,7 @@ func (p *Player) load(data Data) {
 		p.AddEffect(potion)
 	}
 	p.fireTicks.Store(data.FireTicks)
-	p.fallDistance.Store(data.FallDistance)
+	p.fall.SetFallDistance(data.FallDistance)
 
 	p.loadInventory(data.Inventory)
 }
@@ -2643,7 +2605,7 @@ func (p *Player) Data() Data {
 		},
 		Effects:      p.Effects(),
 		FireTicks:    p.fireTicks.Load(),
-		FallDistance: p.fallDistance.Load(),
+		FallDistance: p.fall.FallDistance(),
 		Dimension:    p.World().Dimension().EncodeDimension(),
 	}
 }