Add "ghost" bullets & networking

scene/Player.tscn

@@ -68,10 +68,11 @@ texture = ExtResource( 7 )
 offset = Vector2( 8, 0 )
 script = ExtResource( 8 )
 Knockback = 50.0
-Spread = 3.0
+Spread = 1.5
 SpreadIncrease = 1.0
 RecoilMin = 3.0
 RecoilMax = 5.0
+BulletSpeed = 1200
 
 [node name="Tip" type="Node2D" parent="Items/Revolver"]
 position = Vector2( 15, -2.5 )
@@ -87,10 +88,13 @@ script = ExtResource( 8 )
 EffectiveRange = 240
 MaximumRange = 360
 Knockback = 135.0
-Spread = 14.0
-SpreadIncrease = 20.0
+Spread = 8.0
+SpreadIncrease = 10.0
 RecoilMin = 6.0
 RecoilMax = 12.0
+BulletSpeed = 1000
+BulletsPetShot = 8
+BulletOpacity = 0.1
 
 [node name="Tip" type="Node2D" parent="Items/Shotgun"]
 position = Vector2( 22, -1.5 )
@@ -109,6 +113,8 @@ Knockback = 100.0
 SpreadIncrease = 2.0
 RecoilMin = 8.0
 RecoilMax = 8.0
+BulletSpeed = 4000
+BulletOpacity = 0.4
 
 [node name="Tip" type="Node2D" parent="Items/Rifle"]
 position = Vector2( 24, -1.5 )
@@ -122,8 +128,8 @@ texture = ExtResource( 12 )
 offset = Vector2( 8, 0 )
 script = ExtResource( 8 )
 Knockback = 30.0
-Spread = 1.0
-SpreadIncrease = 1.2
+Spread = 0.6
+SpreadIncrease = 0.8
 RecoilMin = 1.0
 RecoilMax = 2.5
 

src/Items/Weapon.cs

@@ -13,6 +13,10 @@ public class Weapon : Sprite
     [Export] public float RecoilMin { get; set; } = 0.0F;
     [Export] public float RecoilMax { get; set; } = 0.0F;
 
+    [Export] public int BulletSpeed { get; set; } = 2000;
+    [Export] public int BulletsPetShot { get; set; } = 1;
+    [Export] public float BulletOpacity { get; set; } = 0.2F;
+
 
     public Cursor Cursor { get; private set; }
     public Player Player { get; private set; }
@@ -34,14 +38,45 @@ public class Weapon : Sprite
         if (!(Player is LocalPlayer localPlayer)) return;
 
         if (ev.IsActionPressed("interact_primary")) {
+            var seed = unchecked((int)GD.Randi());
+            ShootInternal(AimDirection, Scale.y > 0, seed);
+            RpcId(1, nameof(Shoot), AimDirection, Scale.y > 0, seed);
+            localPlayer.Velocity -= Mathf.Polar2Cartesian(Knockback, Rotation);
+        }
+    }
+
+    [Remote]
+    private void Shoot(float aimDirection, bool toRight, int seed)
+    {
+        if (this.GetGame() is Server) {
+            if (Player.NetworkID != GetTree().GetRpcSenderId()) return;
+            // TODO: Verify input.
+            Rpc(nameof(Shoot), aimDirection, toRight, seed);
+        } else if (Player is LocalPlayer) return;
+        ShootInternal(aimDirection, toRight, seed);
+    }
+    private void ShootInternal(float aimDirection, bool toRight, int seed)
+    {
+        if (this.GetGame() is Client)
             GetNodeOrNull<AudioStreamPlayer2D>("Fire")?.Play();
-            // TODO: Spawn bullet or something.
-            // TODO: Tell server (and other clients) we shot.
-            _currentSpreadInc += Mathf.Deg2Rad(SpreadIncrease);
-            _currentRecoil    += Mathf.Deg2Rad((float)GD.RandRange(RecoilMin, RecoilMax));
 
-            localPlayer.Velocity -= Mathf.Polar2Cartesian(Knockback, Rotation);
+        var random = new Random(seed);
+        var angle = aimDirection - _currentRecoil * (toRight ? 1 : -1);
+
+        var tip = GetNode<Node2D>("Tip").Position;
+        if (!toRight) tip.y *= -1;
+        tip = tip.Rotated(angle);
+
+        for (var i = 0; i < BulletsPetShot; i++) {
+            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, BulletSpeed, color);
+            this.GetWorld().AddChild(bullet);
         }
+
+        _currentSpreadInc += Mathf.Deg2Rad(SpreadIncrease);
+        _currentRecoil    += Mathf.Deg2Rad(random.NextFloat(RecoilMin, RecoilMax));
     }
 
     public override void _Process(float delta)

src/Objects/Bullet.cs

@@ -0,0 +1,72 @@
+using System;
+using Godot;
+
+public class Bullet : Node2D
+{
+    private static readonly TimeSpan TRAIL_DURATION = TimeSpan.FromSeconds(0.6);
+
+    public Vector2 Direction { get; }
+    public int EffectiveRange { get; }
+    public int MaximumRange { get; }
+    public int Speed { get; }
+    public Color Color { get; }
+
+    private readonly Vector2 _startPosition;
+    private TimeSpan _age;
+    private float _distance;
+
+    public Bullet(Vector2 position, Vector2 direction,
+        int effectiveRange, int maximumRange, int speed, Color color)
+    {
+        _startPosition = Position = position;
+        Direction      = direction;
+        EffectiveRange = effectiveRange;
+        MaximumRange   = maximumRange;
+        Speed = speed;
+        Color = color;
+    }
+
+    public override void _Ready()
+        { if (this.GetGame() is Server) Visible = false; }
+
+    public override void _Process(float delta)
+    {
+        _age += TimeSpan.FromSeconds(delta);
+
+        if (_distance < MaximumRange) {
+            _distance = Mathf.Min(MaximumRange, Speed * (float)_age.TotalSeconds);
+            Position = _startPosition + Direction * _distance;
+            Update();
+        }
+
+        if (_age > TRAIL_DURATION) {
+            Modulate = new Color(Modulate, Modulate.a - delta * 2);
+            if (Modulate.a <= 0) this.RemoveFromParent();
+        }
+    }
+
+    public override void _Draw()
+    {
+        var numPoints = 2
+            + ((_distance > 16) ? 1 : 0)
+            + ((_distance > EffectiveRange) ? 1 : 0);
+        var points = new Vector2[numPoints];
+        var colors = new Color[numPoints];
+
+        if (_distance > 16)
+            colors[0] = new Color(Color, Color.a * Mathf.Min(1.0F, 1.0F - (_distance - EffectiveRange) / (MaximumRange - EffectiveRange)));
+
+        if (_distance > EffectiveRange) {
+            points[1] = Direction * -(_distance - EffectiveRange);
+            colors[1] = Color;
+        }
+
+        points[points.Length - 2] = Direction * -Mathf.Max(0.0F, _distance - 16);
+        points[points.Length - 1] = Direction * -_distance;
+
+        colors[colors.Length - 2] = Color;
+        colors[colors.Length - 1] = new Color(Color, 0.0F);
+
+        DrawPolylineColors(points, colors, 1.5F, true);
+    }
+}

src/Utility/Extensions.cs

@@ -1,3 +1,4 @@
+using System;
 using Godot;
 
 public static class Extensions
@@ -24,6 +25,19 @@ public static class Extensions
         node.GetParent().RemoveChild(node);
         node.QueueFree();
     }
+
+    public static float NextFloat(this Random random)
+        => (float)random.NextDouble();
+    public static float NextFloat(this Random random, float min, float max)
+        => min + NextFloat(random) * (max - min);
+
+    public static float NextGaussian(this Random random, float stdDev = 1.0F, float mean = 0.0F)
+    {
+        var u1 = 1.0F - random.NextFloat();
+        var u2 = 1.0F - random.NextFloat();
+        var normal = Mathf.Sqrt(-2.0F * Mathf.Log(u1)) * Mathf.Sin(2.0F * Mathf.Pi * u2);
+        return  mean + stdDev * normal;
+    }
 }
 
 public interface IInitializable