From dccab83a009dc175d269d478d58fb0a515c24240 Mon Sep 17 00:00:00 2001
From: Evan Hemsley <evan@moonside.games>
Date: Wed, 15 Jul 2020 18:31:49 -0700
Subject: [PATCH] random serve

---
 PongFE/Engines/DestroyEngine.cs        |  2 +-
 PongFE/Engines/Spawners/BallSpawner.cs | 10 ++++++++--
 PongFE/Extensions/Vector2Extensions.cs |  9 +++++++--
 PongFE/Messages/BallSpawnMessage.cs    |  7 +++----
 PongFE/PongFEGame.cs                   |  2 +-
 PongFE/Utility/MathHelper.cs           | 26 ++++++++++++++++++++++++++
 6 files changed, 46 insertions(+), 10 deletions(-)
 create mode 100644 PongFE/Utility/MathHelper.cs

diff --git a/PongFE/Engines/DestroyEngine.cs b/PongFE/Engines/DestroyEngine.cs
index cd92c49..6b34131 100644
--- a/PongFE/Engines/DestroyEngine.cs
+++ b/PongFE/Engines/DestroyEngine.cs
@@ -20,7 +20,7 @@ namespace PongFE.Engines
                     SendMessage(
                         new BallSpawnMessage(
                             new MoonTools.Structs.Position2D(640, 360),
-                            new System.Numerics.Vector2(-200, 100),
+                            300,
                             16,
                             16
                         ),
diff --git a/PongFE/Engines/Spawners/BallSpawner.cs b/PongFE/Engines/Spawners/BallSpawner.cs
index d53d132..bc38655 100644
--- a/PongFE/Engines/Spawners/BallSpawner.cs
+++ b/PongFE/Engines/Spawners/BallSpawner.cs
@@ -1,7 +1,9 @@
+using System.Numerics;
 using Encompass;
 using Microsoft.Xna.Framework.Graphics;
 using PongFE.Components;
 using PongFE.Messages;
+using PongFE.Extensions;
 
 namespace PongFE.Spawners
 {
@@ -17,10 +19,14 @@ namespace PongFE.Spawners
         protected override void Spawn(BallSpawnMessage message)
         {
             var ball = CreateEntity();
+
+            var direction = MathHelper.RandomDouble(-System.Math.PI / 4.0, System.Math.PI / 4.0);
+            var velocity = new Vector2(message.Speed * (MathHelper.CoinFlip() ? -1 : 1), 0).Rotate((float)direction);
+
             AddComponent(ball, new PositionComponent(message.Position));
-            AddComponent(ball, new VelocityComponent(message.Velocity));
+            AddComponent(ball, new VelocityComponent(velocity));
             AddComponent(ball, new CollisionComponent(new MoonTools.Bonk.Rectangle(0, 0, 16, 16)));
-            AddComponent(ball, new Texture2DComponent(WhitePixel, 0, new System.Numerics.Vector2(message.Width, message.Height)));
+            AddComponent(ball, new Texture2DComponent(WhitePixel, 0, new Vector2(message.Width, message.Height)));
             AddComponent(ball, new CanBeBouncedComponent());
             AddComponent(ball, new BounceResponseComponent());
             AddComponent(ball, new CanBeTrackedComponent());
diff --git a/PongFE/Extensions/Vector2Extensions.cs b/PongFE/Extensions/Vector2Extensions.cs
index bd4b7fa..1cbb3b2 100644
--- a/PongFE/Extensions/Vector2Extensions.cs
+++ b/PongFE/Extensions/Vector2Extensions.cs
@@ -1,12 +1,17 @@
-using MoonTools.Structs;
+using System.Numerics;
 
 namespace PongFE.Extensions
 {
     public static class Vector2Extensions
     {
-        public static Microsoft.Xna.Framework.Vector2 ToXNAVector(this System.Numerics.Vector2 vector)
+        public static Microsoft.Xna.Framework.Vector2 ToXNAVector(this Vector2 vector)
         {
             return new Microsoft.Xna.Framework.Vector2(vector.X, vector.Y);
         }
+
+        public static Vector2 Rotate(this Vector2 vector, float radians)
+        {
+            return Vector2.Transform(vector, Matrix3x2.CreateRotation(radians));
+        }
     }
 }
diff --git a/PongFE/Messages/BallSpawnMessage.cs b/PongFE/Messages/BallSpawnMessage.cs
index 3e18eea..24e1247 100644
--- a/PongFE/Messages/BallSpawnMessage.cs
+++ b/PongFE/Messages/BallSpawnMessage.cs
@@ -1,4 +1,3 @@
-using System.Numerics;
 using Encompass;
 using MoonTools.Structs;
 
@@ -7,14 +6,14 @@ namespace PongFE.Messages
     public struct BallSpawnMessage : IMessage
     {
         public Position2D Position { get; }
-        public Vector2 Velocity { get; }
+        public float Speed { get; }
         public int Width { get; }
         public int Height { get; }
 
-        public BallSpawnMessage(Position2D position, Vector2 velocity, int width, int height)
+        public BallSpawnMessage(Position2D position, float speed, int width, int height)
         {
             Position = position;
-            Velocity = velocity;
+            Speed = speed;
             Width = width;
             Height = height;
         }
diff --git a/PongFE/PongFEGame.cs b/PongFE/PongFEGame.cs
index 9dbb674..acf8e0a 100644
--- a/PongFE/PongFEGame.cs
+++ b/PongFE/PongFEGame.cs
@@ -80,7 +80,7 @@ namespace PongFE
             WorldBuilder.SendMessage(
                 new BallSpawnMessage(
                     new MoonTools.Structs.Position2D(640, 360),
-                    new System.Numerics.Vector2(-300, 200),
+                    300,
                     16,
                     16
                 )
diff --git a/PongFE/Utility/MathHelper.cs b/PongFE/Utility/MathHelper.cs
new file mode 100644
index 0000000..f8fba42
--- /dev/null
+++ b/PongFE/Utility/MathHelper.cs
@@ -0,0 +1,26 @@
+using System;
+
+public static class MathHelper
+{
+    private readonly static Random s_random = new Random();
+
+    public static double RandomDouble(double min, double max)
+    {
+        return (s_random.NextDouble() * (max - min)) + min;
+    }
+
+    public static float RandomFloat(float min, float max)
+    {
+        return (float)RandomDouble(min, max);
+    }
+
+    public static int Dice(int n)
+    {
+        return (int)Math.Floor(RandomDouble(0, n));
+    }
+
+    public static bool CoinFlip()
+    {
+        return Dice(2) == 0;
+    }
+}