From 286dfb8061d60ab15efe524e59e746e101d6de89 Mon Sep 17 00:00:00 2001
From: copygirl <copygirl@mcft.net>
Date: Tue, 18 May 2021 14:51:47 +0200
Subject: [PATCH] Implement health, death & respawn

- Add Health HUD element
- Add Damage to weapons
- Bullet does damage to players
- Players die and respawn
- Hit decal spawned by server
- Disable various processing
  when player is not alive
---
 scene/ClientScene.tscn        | 10 ++--
 scene/Player.tscn             |  4 ++
 src/HUD/Health.cs             | 94 +++++++++++++++++++++++++++++++++++
 src/HUD/RadialMenu.cs         | 32 +++++-------
 src/Items/CreativeBuilding.cs |  9 ++--
 src/Items/Weapon.cs           | 25 +++++++---
 src/Objects/Bullet.cs         | 24 ++++++---
 src/Objects/HitDecal.cs       |  1 -
 src/Objects/LocalPlayer.cs    |  2 +-
 src/Objects/Player.cs         | 47 ++++++++++++++++--
 src/World.cs                  | 10 ++++
 11 files changed, 213 insertions(+), 45 deletions(-)
 create mode 100644 src/HUD/Health.cs

diff --git a/scene/ClientScene.tscn b/scene/ClientScene.tscn
index 70cc1d7..9ec383a 100644
--- a/scene/ClientScene.tscn
+++ b/scene/ClientScene.tscn
@@ -1,4 +1,4 @@
-[gd_scene load_steps=16 format=2]
+[gd_scene load_steps=17 format=2]
 
 [ext_resource path="res://scene/GameScene.tscn" type="PackedScene" id=1]
 [ext_resource path="res://src/HUD/Cursor.cs" type="Script" id=2]
@@ -12,6 +12,7 @@
 [ext_resource path="res://ui_theme.tres" type="Theme" id=10]
 [ext_resource path="res://src/HUD/RadialMenu.cs" type="Script" id=11]
 [ext_resource path="res://src/HUD/WeaponInfo.cs" type="Script" id=12]
+[ext_resource path="res://src/HUD/Health.cs" type="Script" id=13]
 
 [sub_resource type="StyleBoxFlat" id=1]
 bg_color = Color( 0, 0, 0, 0.752941 )
@@ -63,7 +64,10 @@ __meta__ = {
 
 [node name="HUD" type="CanvasLayer" parent="." index="4"]
 
-[node name="RadialMenu" type="Node2D" parent="HUD" index="0"]
+[node name="Health" type="Node2D" parent="HUD" index="0"]
+script = ExtResource( 13 )
+
+[node name="RadialMenu" type="Node2D" parent="HUD" index="1"]
 visible = false
 script = ExtResource( 11 )
 
@@ -84,7 +88,7 @@ __meta__ = {
 "_edit_use_anchors_": false
 }
 
-[node name="EscapeMenu" parent="HUD" index="1" instance=ExtResource( 7 )]
+[node name="EscapeMenu" parent="HUD" index="2" instance=ExtResource( 7 )]
 visible = false
 
 [node name="CursorLayer" type="CanvasLayer" parent="." index="5"]
diff --git a/scene/Player.tscn b/scene/Player.tscn
index cd74a8a..e70697a 100644
--- a/scene/Player.tscn
+++ b/scene/Player.tscn
@@ -76,6 +76,7 @@ SpreadIncrease = 1.0
 RecoilMin = 3.0
 RecoilMax = 5.0
 BulletVelocity = 1200
+Damage = 0.22
 
 [node name="Tip" type="Node2D" parent="Items/Revolver"]
 position = Vector2( 15, -2.5 )
@@ -99,6 +100,7 @@ EffectiveRange = 240
 MaximumRange = 360
 BulletVelocity = 1000
 BulletsPerShot = 6
+Damage = 0.6
 BulletOpacity = 0.1
 
 [node name="Tip" type="Node2D" parent="Items/Shotgun"]
@@ -121,6 +123,7 @@ RecoilMax = 8.0
 EffectiveRange = 480
 MaximumRange = 920
 BulletVelocity = 4000
+Damage = 0.8
 BulletOpacity = 0.4
 
 [node name="Tip" type="Node2D" parent="Items/Rifle"]
@@ -143,6 +146,7 @@ Spread = 0.6
 SpreadIncrease = 0.8
 RecoilMin = 1.0
 RecoilMax = 2.5
+Damage = 0.12
 BulletOpacity = 0.15
 
 [node name="Tip" type="Node2D" parent="Items/Assault Rifle"]
diff --git a/src/HUD/Health.cs b/src/HUD/Health.cs
new file mode 100644
index 0000000..c8a8654
--- /dev/null
+++ b/src/HUD/Health.cs
@@ -0,0 +1,94 @@
+using System;
+using Godot;
+
+public class Health : Node2D
+{
+    private static readonly TimeSpan VISIBLE_TIME = TimeSpan.FromSeconds(1.0);
+    private static readonly TimeSpan FADE_TIME    = TimeSpan.FromSeconds(1.5);
+
+    [Export] public int Segments { get; set; } = 6;
+    [Export] public int InnerRadius { get; set; } = 14;
+    [Export] public int OuterRadius { get; set; } = 24;
+    [Export] public float Separation { get; set; } = 2.0F;
+
+    private float _startAngle;
+    private float _health;
+    private float _visibilityTimer;
+
+    public override void _Ready()
+    {
+        _startAngle = (-Mathf.Tau / 4) - (Mathf.Tau / Segments / 2);
+        Visible = false;
+    }
+
+    public override void _Process(float delta)
+    {
+        if (!(this.GetClient().LocalPlayer is Player player))
+            { Visible = false; return; }
+
+        if (player.Health >= 1.0F) {
+            if (!Visible) return;
+            _visibilityTimer += delta;
+            if (_visibilityTimer > (VISIBLE_TIME + FADE_TIME).TotalSeconds)
+                { Visible = false; return; }
+            else if (_visibilityTimer > VISIBLE_TIME.TotalSeconds)
+                Modulate = new Color(Colors.White, 1.0F - (float)(
+                    (_visibilityTimer - VISIBLE_TIME.TotalSeconds) / FADE_TIME.TotalSeconds));
+        } else {
+            Visible  = true;
+            Modulate = Colors.White;
+            _visibilityTimer = 0.0F;
+        }
+
+        Position = player.GetGlobalTransformWithCanvas().origin;
+        _health  = player.Health;
+
+        Update();
+    }
+
+    public override void _Draw()
+    {
+        var vertices = new Vector2[6];
+
+        for (var i = 0; i < Segments; i++) {
+            var angle1 = _startAngle + Mathf.Tau * ( i      / (float)Segments);
+            var angle3 = _startAngle + Mathf.Tau * ((i + 1) / (float)Segments);
+            var angle2 = (angle1 + angle3) / 2;
+
+            var sep1 = Mathf.Polar2Cartesian(Separation, angle1 + Mathf.Tau / 4);
+            var sep2 = Mathf.Polar2Cartesian(Separation, angle3 - Mathf.Tau / 4);
+
+            vertices[0] = Mathf.Polar2Cartesian(InnerRadius, angle2);
+            vertices[1] = Mathf.Polar2Cartesian(InnerRadius, angle1) + sep1;
+            vertices[2] = Mathf.Polar2Cartesian(OuterRadius, angle1) + sep1;
+            vertices[3] = Mathf.Polar2Cartesian(OuterRadius, angle2);
+            vertices[4] = Mathf.Polar2Cartesian(OuterRadius, angle3) + sep2;
+            vertices[5] = Mathf.Polar2Cartesian(InnerRadius, angle3) + sep2;
+
+            DrawColoredPolygon(vertices, new Color(Colors.Black, 0.4F), antialiased: true);
+        }
+
+        for (var i = 0; i < Segments; i++) {
+            var fullness = Mathf.Clamp((_health * Segments) - i, 0.0F, 1.0F);
+            if (fullness <= 0.1) return;
+
+            var angle1 = _startAngle + Mathf.Tau * ( i      / (float)Segments);
+            var angle3 = _startAngle + Mathf.Tau * ((i + 1) / (float)Segments);
+            var angle2 = (angle1 + angle3) / 2;
+
+            var sep1 = Mathf.Polar2Cartesian(Separation + 1, angle1 + Mathf.Tau / 4);
+            var sep2 = Mathf.Polar2Cartesian(Separation + 1, angle3 - Mathf.Tau / 4);
+
+            var outerRadius = Mathf.Lerp(InnerRadius, OuterRadius, fullness);
+
+            vertices[0] = Mathf.Polar2Cartesian(InnerRadius + 1, angle2);
+            vertices[1] = Mathf.Polar2Cartesian(InnerRadius + 1, angle1) + sep1;
+            vertices[2] = Mathf.Polar2Cartesian(outerRadius - 1, angle1) + sep1;
+            vertices[3] = Mathf.Polar2Cartesian(outerRadius - 1, angle2);
+            vertices[4] = Mathf.Polar2Cartesian(outerRadius - 1, angle3) + sep2;
+            vertices[5] = Mathf.Polar2Cartesian(InnerRadius + 1, angle3) + sep2;
+
+            DrawColoredPolygon(vertices, new Color(Colors.Red, 0.5F), antialiased: true);
+        }
+    }
+}
diff --git a/src/HUD/RadialMenu.cs b/src/HUD/RadialMenu.cs
index bb5a644..6f37982 100644
--- a/src/HUD/RadialMenu.cs
+++ b/src/HUD/RadialMenu.cs
@@ -4,9 +4,9 @@ using Godot;
 // TODO: Display number of rounds for weapons? Add an even smaller font for this?
 public class RadialMenu : Node2D
 {
+    [Export] public int MinSegments { get; set; } = 8;
     [Export] public int InnerRadius { get; set; } = 32;
     [Export] public int OuterRadius { get; set; } = 64;
-    [Export] public int MinElements { get; set; } = 8;
     [Export] public float Separation { get; set; } = 2F;
 
     public Cursor Cursor { get; private set; }
@@ -18,7 +18,7 @@ public class RadialMenu : Node2D
 
     public override void _Ready()
     {
-        _startAngle = (-Mathf.Tau / 4) - (Mathf.Tau / MinElements / 2);
+        _startAngle = (-Mathf.Tau / 4) - (Mathf.Tau / MinSegments / 2);
 
         Cursor     = this.GetClient()?.Cursor;
         ActiveName = GetNode<Label>("ActiveName");
@@ -29,14 +29,14 @@ public class RadialMenu : Node2D
 
     public override void _UnhandledInput(InputEvent ev)
     {
-        if (GetItems() == null) return;
+        if (this.GetClient().LocalPlayer?.IsAlive != true) return;
+        var items = GetItems();
 
         if (ev.IsActionPressed("interact_select")) {
             Position = this.GetClient().Cursor.ScreenPosition.Round();
             Visible  = true;
             Modulate = Colors.White;
 
-            var items = GetItems();
             _selected = items.Current;
             items.Current = null;
 
@@ -47,7 +47,6 @@ public class RadialMenu : Node2D
 
         if (ev.IsActionPressed("interact_select_dec") || ev.IsActionPressed("interact_select_inc")) {
             var diff  = ev.IsActionPressed("interact_select_inc") ? 1 : -1;
-            var items = GetItems();
             // TODO: Should current item be equipped until radial menu disappears again?
             //       Perhaps for balance reasons?
 
@@ -78,6 +77,7 @@ public class RadialMenu : Node2D
 
     public override void _Process(float delta)
     {
+        if (this.GetClient().LocalPlayer?.IsAlive != true) Visible = false;
         if (!Visible) return;
 
         if (_showUntil != null) {
@@ -91,12 +91,10 @@ public class RadialMenu : Node2D
             return;
         }
 
-        var items = GetItems();
-        if (items == null) return;
-
+        var items  = GetItems();
         var cursor = ToLocal(this.GetClient().Cursor.ScreenPosition);
         var angle  = cursor.Angle() - _startAngle;
-        var index  = (int)((angle / Mathf.Tau + 1) % 1 * MinElements);
+        var index  = (int)((angle / Mathf.Tau + 1) % 1 * MinSegments);
         if ((cursor.Length() > InnerRadius) && (index < items.Count) && (items[index] != _selected)) {
             _selected = items[index];
             ActiveName.Text = _selected?.Name ?? "";
@@ -111,15 +109,13 @@ public class RadialMenu : Node2D
 
     public override void _Draw()
     {
-        var items = GetItems();
-
+        var items    = GetItems();
         var vertices = new Vector2[5];
-        var colors   = new Color[5];
 
-        var numElements = Math.Max(MinElements, items.Count);
-        for (var i = 0; i < numElements; i++) {
-            var angle1 = _startAngle + Mathf.Tau * ( i      / (float)numElements);
-            var angle3 = _startAngle + Mathf.Tau * ((i + 1) / (float)numElements);
+        var numSegments = Math.Max(MinSegments, items.Count);
+        for (var i = 0; i < numSegments; i++) {
+            var angle1 = _startAngle + Mathf.Tau * ( i      / (float)numSegments);
+            var angle3 = _startAngle + Mathf.Tau * ((i + 1) / (float)numSegments);
             var angle2 = (angle1 + angle3) / 2;
 
             var sep1 = Mathf.Polar2Cartesian(Separation, angle1 + Mathf.Tau / 4);
@@ -136,9 +132,7 @@ public class RadialMenu : Node2D
             vertices[4] = Mathf.Polar2Cartesian(innerRadius             , angle3) + sep2;
 
             var color = new Color(0.1F, 0.1F, 0.1F, isSelected ? 0.7F : 0.4F);
-            for (var j = 0; j < colors.Length; j++) colors[j] = color;
-
-            DrawPolygon(vertices, colors, antialiased: true);
+            DrawColoredPolygon(vertices, color, antialiased: true);
 
             if (i < items.Count) {
                 var sprite = (items[i].GetNodeOrNull("Icon") as Sprite) ?? (items[i] as Sprite);
diff --git a/src/Items/CreativeBuilding.cs b/src/Items/CreativeBuilding.cs
index 57904d1..24d014b 100644
--- a/src/Items/CreativeBuilding.cs
+++ b/src/Items/CreativeBuilding.cs
@@ -35,7 +35,7 @@ public class CreativeBuilding : Node2D
 
     public override void _UnhandledInput(InputEvent ev)
     {
-        if (!Visible || !(Player is LocalPlayer)) return;
+        if (!Visible || !(Player is LocalPlayer) || !Player.IsAlive) return;
 
         if (ev.IsActionPressed("interact_primary")) {
             GetTree().SetInputAsHandled();
@@ -52,7 +52,7 @@ public class CreativeBuilding : Node2D
     public override void _Process(float delta)
     {
         if (!(Player is LocalPlayer)) return;
-        if (!Visible) _currentMode = null;
+        if (!Visible || !Player.IsAlive) _currentMode = null;
 
         if (_currentMode == BuildMode.Placing) {
             if (!_canBuild) _currentMode = null;
@@ -88,7 +88,8 @@ public class CreativeBuilding : Node2D
 
     public override void _Draw()
     {
-        if (!Cursor.Visible || EscapeMenu.Instance.Visible) return;
+        if (!(Player is LocalPlayer) || !Cursor.Visible ||
+            EscapeMenu.Instance.Visible) return;
 
         var green = Color.FromHsv(1.0F / 3, 1.0F, 1.0F, 0.4F);
         var red   = Color.FromHsv(0.0F, 1.0F, 1.0F, 0.4F);
@@ -112,6 +113,7 @@ public class CreativeBuilding : Node2D
     private void PlaceLine(int x, int y, Facing direction, int length)
     {
         if (Player.NetworkID != GetTree().GetRpcSenderId()) return;
+        if (!Player.IsAlive) return;
 
         // TODO: Make sure position is a reasonable distance away.
         if (!Enum.IsDefined(typeof(Facing), direction)) return;
@@ -133,6 +135,7 @@ public class CreativeBuilding : Node2D
     private void BreakLine(int x, int y, Facing direction, int length)
     {
         if (Player.NetworkID != GetTree().GetRpcSenderId()) return;
+        if (!Player.IsAlive) return;
 
         // TODO: Make sure position is a reasonable distance away.
         if (!Enum.IsDefined(typeof(Facing), direction)) return;
diff --git a/src/Items/Weapon.cs b/src/Items/Weapon.cs
index 6ce31ac..e30e661 100644
--- a/src/Items/Weapon.cs
+++ b/src/Items/Weapon.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Security.Cryptography.X509Certificates;
 using Godot;
 
 // TODO: "Click" sound when attempting to fire when not ready, or empty.
@@ -22,6 +23,7 @@ public class Weapon : Sprite
     [Export] public int MaximumRange    { get; set; } = 640;
     [Export] public int BulletVelocity  { get; set; } = 2000;
     [Export] public int BulletsPerShot  { get; set; } = 1;
+    [Export] public float Damage        { get; set; } = 0.0F;
     [Export] public float BulletOpacity { get; set; } = 0.2F;
 
 
@@ -71,7 +73,14 @@ public class Weapon : Sprite
         _currentSpreadInc = Mathf.Max(0, _currentSpreadInc - spreadDecrease * delta);
         _currentRecoil    = Mathf.Max(0, _currentRecoil    - recoilDecrease * delta);
 
-        if (Visible) {
+        if (!Player.IsAlive) {
+            _fireDelay     = 0.0F;
+            _reloading     = null;
+            Rounds         = Capacity;
+            HoldingTrigger = null;
+            // TODO: Technically only needs to be called once.
+            if (Player is LocalPlayer) Update();
+        } else if (Visible) {
             if (HoldingTrigger is TimeSpan holding)
                 HoldingTrigger = holding + TimeSpan.FromSeconds(delta);
 
@@ -152,7 +161,7 @@ public class Weapon : Sprite
     private void SendAimAngle(float value)
     {
         if (this.GetGame() is Server) {
-            if (Player.NetworkID != GetTree().GetRpcSenderId()) return;
+            if ((Player.NetworkID != GetTree().GetRpcSenderId()) || !Player.IsAlive) return;
             if (float.IsNaN(value = Mathf.PosMod(value, Mathf.Tau))) return;
 
             RPC.Unreliable(SendAimAngle, value);
@@ -171,7 +180,8 @@ public class Weapon : Sprite
 
     protected virtual bool FireInternal(float aimDirection, bool toRight, int seed)
     {
-        if (!Visible || _lowered || (_reloading != null) || (Rounds <= 0) || (_fireDelay > 0)) return false;
+        if (!Visible || _lowered || !Player.IsAlive ||
+            (_reloading != null) || (Rounds <= 0) || (_fireDelay > 0)) return false;
 
         if (this.GetGame() is Client)
             GetNodeOrNull<AudioStreamPlayer2D>("Fire")?.Play();
@@ -184,7 +194,8 @@ public class Weapon : Sprite
             var spread = (Mathf.Deg2Rad(Spread) + _currentSpreadInc) * Mathf.Clamp(random.NextGaussian(0.4F), -1, 1);
             var dir    = Mathf.Polar2Cartesian(1, angle + spread);
             var color  = new Color(Player.Color, BulletOpacity);
-            var bullet = new Bullet(Player.Position + tip, dir, EffectiveRange, MaximumRange, BulletVelocity, color);
+            var bullet = new Bullet(Player.Position + tip, dir, EffectiveRange, MaximumRange,
+                                    BulletVelocity, Damage / BulletsPerShot, color);
             this.GetWorld().AddChild(bullet);
         }
 
@@ -218,7 +229,9 @@ public class Weapon : Sprite
 
     private bool ReloadInternal()
     {
-        if (!Visible || (Rounds >= Capacity) || (_reloading != null)) return false;
+        if (!Visible || !Player.IsAlive ||
+            (Rounds >= Capacity) || (_reloading != null)) return false;
+
         // TODO: Play reload sound.
         _reloading = ReloadTime;
         return true;
@@ -237,7 +250,7 @@ public class Weapon : Sprite
 
     public override void _Draw()
     {
-        if (!(Player is LocalPlayer) || _lowered) return;
+        if (!(Player is LocalPlayer) || !Player.IsAlive || _lowered) return;
         // Draws an "aiming cone" to show where bullets might travel.
 
         var tip   = TipOffset + new Vector2(4, 0);
diff --git a/src/Objects/Bullet.cs b/src/Objects/Bullet.cs
index c266f9a..26b2c9f 100644
--- a/src/Objects/Bullet.cs
+++ b/src/Objects/Bullet.cs
@@ -5,12 +5,12 @@ public class Bullet : Node2D
 {
     private static readonly TimeSpan LIFE_TIME = TimeSpan.FromSeconds(0.6);
     private static readonly TimeSpan FADE_TIME = TimeSpan.FromSeconds(0.6);
-    private static readonly PackedScene HIT_DECAL = GD.Load<PackedScene>("res://scene/HitDecal.tscn");
 
     public Vector2 Direction { get; }
     public int EffectiveRange { get; }
     public int MaximumRange { get; }
     public int Velocity { get; }
+    public float Damage { get; }
     public Color Color { get; }
 
     private readonly Vector2 _startPosition;
@@ -18,24 +18,32 @@ public class Bullet : Node2D
     private float _distance;
 
     public Bullet(Vector2 position, Vector2 direction,
-        int effectiveRange, int maximumRange, int velocity, Color color)
+        int effectiveRange, int maximumRange, int velocity,
+        float damage, Color color)
     {
         _startPosition = Position = position;
         Direction      = direction;
         EffectiveRange = effectiveRange;
         MaximumRange   = maximumRange;
         Velocity = velocity;
+        Damage   = damage;
         Color    = color;
     }
 
-    protected void OnCollide(CollisionObject2D obj, Vector2 hitPosition)
+    protected virtual void OnCollide(CollisionObject2D obj, Vector2 hitPosition)
     {
-        var sprite = obj.GetNodeOrNull<Sprite>("Sprite");
-        if (sprite == null) return;
-
-        var hole  = HIT_DECAL.Init<HitDecal>();
+        // TODO: Add a global game setting to specify whether shooter or server announces successful hit.
+        //       For now, server is the most straight-forward. Eventually, support client predictive movement?
+        if (!(this.GetGame() is Server) || !(obj.GetNodeOrNull("Sprite") is Sprite sprite)) return;
+        var world = this.GetWorld();
+        var path  = world.GetPathTo(sprite);
         var color = new Color(Color, (1 + Color.a) / 2);
-        hole.Add(sprite, hitPosition, color);
+        RPC.Reliable(world.SpawnHit, path, hitPosition, color);
+        if (obj is Player player) {
+            var rangeFactor = Math.Min(1.0F, (MaximumRange - _distance) / (MaximumRange - EffectiveRange));
+            player.Health -= Damage * rangeFactor;
+        }
+        // TODO: Also spawn a ghost of the player who was hit so they can see where they got shot?
     }
 
     public override void _Ready()
diff --git a/src/Objects/HitDecal.cs b/src/Objects/HitDecal.cs
index abce850..703c71d 100644
--- a/src/Objects/HitDecal.cs
+++ b/src/Objects/HitDecal.cs
@@ -1,7 +1,6 @@
 using System;
 using Godot;
 
-// TODO: When spawned, add to multiple nearby sprites.
 public class HitDecal : Sprite
 {
     private static readonly TimeSpan LIFE_TIME = TimeSpan.FromSeconds(5.0);
diff --git a/src/Objects/LocalPlayer.cs b/src/Objects/LocalPlayer.cs
index e37b6f2..88a33df 100644
--- a/src/Objects/LocalPlayer.cs
+++ b/src/Objects/LocalPlayer.cs
@@ -30,7 +30,7 @@ public class LocalPlayer : Player
     {
         var moveDir     = 0.0F;
         var jumpPressed = false;
-        if (!EscapeMenu.Instance.Visible) {
+        if (!EscapeMenu.Instance.Visible && IsAlive) {
             moveDir     = Input.GetActionStrength("move_right") - Input.GetActionStrength("move_left");
             jumpPressed = Input.IsActionJustPressed("move_jump");
         }
diff --git a/src/Objects/Player.cs b/src/Objects/Player.cs
index 20c6fd8..e6cf5de 100644
--- a/src/Objects/Player.cs
+++ b/src/Objects/Player.cs
@@ -1,7 +1,13 @@
+using System;
 using Godot;
 
 public class Player : KinematicBody2D, IInitializable
 {
+    private static readonly TimeSpan TIME_BEFORE_REGEN = TimeSpan.FromSeconds(1.0);
+    private static readonly TimeSpan REGEN_TIMER = TimeSpan.FromSeconds(1.0 / 3);
+    private static readonly float REGEN_AMOUNT = 0.025F;
+    private static readonly TimeSpan RESPAWN_TIMER = TimeSpan.FromSeconds(5);
+
     [Export] public NodePath DisplayNamePath { get; set; }
     [Export] public NodePath SpritePath { get; set; }
 
@@ -9,11 +15,16 @@ public class Player : KinematicBody2D, IInitializable
     public Sprite Sprite { get; private set; }
     public IItems Items { get; private set; }
 
-
     public int NetworkID { get => int.Parse(Name); set => Name = value.ToString(); }
     public string DisplayName { get => DisplayNameLabel.Text; set => DisplayNameLabel.Text = value; }
     public Color Color { get => Sprite.Modulate; set => Sprite.Modulate = value; }
 
+    public float Health { get; set; } = 1.0F;
+    public bool IsAlive => Health > 0.0F;
+    private float _previousHealth;
+    private float _regenDelay;
+    private float _respawnDelay;
+
     public void Initialize()
     {
         DisplayNameLabel = GetNode<Label>(DisplayNamePath);
@@ -21,8 +32,10 @@ public class Player : KinematicBody2D, IInitializable
         Items  = GetNode<IItems>("Items");
 
         RsetConfig("position", MultiplayerAPI.RPCMode.Puppetsync);
+        RsetConfig("modulate", MultiplayerAPI.RPCMode.Puppetsync);
         RsetConfig(nameof(DisplayName), MultiplayerAPI.RPCMode.Puppetsync);
         RsetConfig(nameof(Color), MultiplayerAPI.RPCMode.Puppetsync);
+        RsetConfig(nameof(Health), MultiplayerAPI.RPCMode.Puppet);
     }
 
     public override void _Ready()
@@ -30,9 +43,35 @@ public class Player : KinematicBody2D, IInitializable
 
     public override void _Process(float delta)
     {
-        if ((Position.y > 9000) && (this.GetGame() is Server))
-            // Can't use RPC helper method here since player is not a LocalPlayer here.
-            RpcId(NetworkID, nameof(LocalPlayer.ResetPosition), Vector2.Zero);
+        if (this.GetGame() is Server) {
+            if (Position.y > 9000) Health -= 0.01F;
+
+            if (IsAlive && (Health < 1.0F)) {
+                if ((_regenDelay += delta) > (TIME_BEFORE_REGEN + REGEN_TIMER).TotalSeconds) {
+                    _regenDelay -= (float)REGEN_TIMER.TotalSeconds;
+                    Health = Mathf.Min(1.0F, Health + REGEN_AMOUNT);
+                }
+            } else _regenDelay = 0.0F;
+
+            if (!IsAlive && ((_respawnDelay += delta) > RESPAWN_TIMER.TotalSeconds)) {
+                // TODO: Move respawning related code to its own method.
+                // Can't use RPC helper method here since player is not a LocalPlayer here.
+                RpcId(NetworkID, nameof(LocalPlayer.ResetPosition), Vector2.Zero);
+                Rset("modulate", Colors.White);
+                Health        = 1.0F;
+                _respawnDelay = 0.0F;
+                // TODO: Add invulnerability timer? Or some other way to prevent "void" damage
+                //       after server considers player respawned, but it hasn't teleported yet.
+            }
+
+            if (_previousHealth != Health) {
+                RsetId(NetworkID, nameof(Health), Health);
+                if (Health < _previousHealth) _regenDelay = 0.0F;
+                if ((Health <= 0) && (_previousHealth > 0))
+                    Rset("modulate", new Color(0.35F, 0.35F, 0.35F, 0.8F));
+                _previousHealth = Health;
+            }
+        }
     }
 
 
diff --git a/src/World.cs b/src/World.cs
index 0f1610a..088ee18 100644
--- a/src/World.cs
+++ b/src/World.cs
@@ -13,6 +13,8 @@ public class World : Node
     public PackedScene BlockScene { get; private set; }
     public PackedScene PlayerScene { get; private set; }
     public PackedScene LocalPlayerScene { get; private set; }
+    private static readonly PackedScene HIT_DECAL = GD.Load<PackedScene>("res://scene/HitDecal.tscn");
+    // TODO: Make all of these static and readonly, hardcode the values..?
 
     public override void _Ready()
     {
@@ -64,6 +66,14 @@ public class World : Node
             this.GetClient().FireLocalPlayerSpawned(localPlayer);
     }
 
+    [Puppet]
+    public void SpawnHit(NodePath spritePath, Vector2 hitPosition, Color color)
+    {
+        var hit    = HIT_DECAL.Init<HitDecal>();
+        var sprite = this.GetWorld().GetNode<Sprite>(spritePath);
+        hit.Add(sprite, hitPosition, color);
+    }
+
     [PuppetSync]
     public void Despawn(NodePath path)
     {