Feature: Aim asteroids towards the ship when in pursuit mode.

Author: deanthecoder

G33kShell.Desktop/Console/Screensavers/AI/AiBrainBase.cs

@@ -9,10 +9,11 @@
 // 
 // THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND.
 using System;
-using System.Linq;
 using CSharp.Core.AI;
 using CSharp.Core.Extensions;
 using Newtonsoft.Json;
+// ReSharper disable once RedundantUsingDirective
+using System.Linq;
 
 namespace G33kShell.Desktop.Console.Screensavers.AI;
 

G33kShell.Desktop/Console/Screensavers/Asteroids/Asteroid.cs

@@ -13,7 +13,7 @@ public class Asteroid
     private readonly Random m_rand;
     private readonly int m_arenaWidth;
     private readonly int m_arenaHeight;
-    private readonly float m_direction;
+    private float m_direction;
     private readonly Vector2[] m_offsets;
     private static readonly int[] Radii = [2, 4, MaxRadius];
     private static readonly int[] SizeMetrics = [1, 2, 4];
@@ -131,4 +131,10 @@ public float DistanceTo(Vector2 shipPosition)
 
         return MathF.Sqrt(minDist);
     }
+
+    public void AimTowards(Vector2 target)
+    {
+        var direction = target - Position;
+        m_direction = MathF.Atan2(direction.Y, direction.X);
+    }
 }

G33kShell.Desktop/Console/Screensavers/Asteroids/Game.cs

@@ -40,7 +40,12 @@ public override double Rating
             if (m_thrustTicks == 0)
                 return 0.0; // Penalize non-thrusters.
 
-            var rating = 1.0 + Score * Score * HitRatio * Math.Min(m_gameTicks, 20 * 60) * TurnEquality * 0.00001;
+            var rating = 1.0 +
+                         Score * Score *
+                         HitRatio *
+                         Math.Min(m_gameTicks, 20 * 60) *
+                         TurnEquality
+                         * 0.00001;
             return rating * rating;
         }
     }
@@ -91,20 +96,23 @@ public override Game ResetGame()
         m_thrustTicks = 0;
         m_ticksSinceScore = 0;
 
-        EnsureMinimumAsteroidCount();
+        EnsureMinimumAsteroidCount(true);
 
         return this;
     }
 
-    private void EnsureMinimumAsteroidCount()
+    private void EnsureMinimumAsteroidCount(bool aimForShip)
     {
         while (Asteroids.FastSum(o => o.SizeMetric) < 12)
         {
             var pos = new Vector2(GameRand.NextFloat() * ArenaWidth, GameRand.NextFloat() * ArenaHeight);
             if (Vector2.Distance(pos, Ship.Position) < 25)
                 continue; // Too close to the ship.
 
-            Asteroids.Add(new Asteroid(pos, 0.1f, GameRand, ArenaWidth, ArenaHeight));
+            var asteroid = new Asteroid(pos, 0.1f, GameRand, ArenaWidth, ArenaHeight);
+            if (aimForShip)
+                asteroid.AimTowards(Ship.Position);
+            Asteroids.Add(asteroid);
         }
     }
 
@@ -117,7 +125,7 @@ public override void Tick()
         m_ticksSinceScore++;
 
         // Spawn asteroids.
-        EnsureMinimumAsteroidCount();
+        EnsureMinimumAsteroidCount(false);
 
         // Move ship.
         Ship.Move();
@@ -150,7 +158,7 @@ public override void Tick()
         // Check for bullet/asteroid collisions.
         if (Bullets.Count > 0)
         {
-            var bulletsToRemove = new List<Bullet>();
+            List<Bullet> bulletsToRemove = null;
             for (var index = 0; index < Bullets.Count; index++)
             {
                 var bullet = Bullets[index];
@@ -169,14 +177,18 @@ public override void Tick()
                     continue; // Bullet not hitting anything.
 
                 // Bullet hit an asteroid.
+                bulletsToRemove ??= new List<Bullet>();
                 bulletsToRemove.Add(bullet);
                 hitAsteroid.Explode(Asteroids);
                 Score++;
                 m_ticksSinceScore = 0;
             }
 
-            for (var i = 0; i < bulletsToRemove.Count; i++)
-                Bullets.Remove(bulletsToRemove[i]);
+            if (bulletsToRemove != null)
+            {
+                for (var i = 0; i < bulletsToRemove.Count; i++)
+                    Bullets.Remove(bulletsToRemove[i]);
+            }
         }
 
         // Check for ship/asteroid collisions.

G33kShell.Desktop/Console/Screensavers/Asteroids/GameState.cs

@@ -39,7 +39,7 @@ public void FillInputVector(double[] inputVector)
         inputVector[0] = 1.0;
 
         // Find nearest asteroid.
-        var asteroid = m_asteroids.Count == 0 ? null : m_asteroids.FastFindMin(o => Vector2.DistanceSquared(o.Position, m_ship.Position));
+        var asteroid = m_asteroids.Count == 0 ? null : m_asteroids.FastFindMin(o => GetDistanceToAsteroid(o, m_ship));
         if (asteroid != null)
         {
             var relativePos = asteroid.Position - m_ship.Position;
@@ -59,4 +59,7 @@ public void FillInputVector(double[] inputVector)
         inputVector[4] = relativeVelocity.Y.Clamp(-1.0f, 1.0f);
         inputVector[5] = (m_ship.Theta / Math.Tau).Clamp(-1.0f, 1.0f);
     }
+
+    private static float GetDistanceToAsteroid(Asteroid asteroid, Ship ship) =>
+        Vector2.DistanceSquared(asteroid.Position, ship.Position);
 }