add cellular automata generator

2026-04-26 04:20:06 +02:00
parent 7f0869ffa4
commit b2a406ca2b
17 changed files with 937 additions and 1 deletions
--- a/addons/ca_level_generator/CaGenerator.cs
+++ b/addons/ca_level_generator/CaGenerator.cs
@@ -0,0 +1,131 @@
+using System;
+
+namespace Mr.BrickAdventures.Tools.CaLevelGenerator;
+
+public static class CaGenerator
+{
+    public static bool[,] Generate(CaGeneratorSettings s)
+    {
+        var rng = new Random(s.Seed);
+        return s.Mode switch
+        {
+            CaMode.Cave     => GenerateCave(s, rng),
+            CaMode.Platform => GeneratePlatform(s, rng),
+            CaMode.Terrain  => GenerateTerrain(s, rng),
+            _               => GenerateCave(s, rng),
+        };
+    }
+
+    public static bool[,] Smooth(bool[,] grid) => SmoothPass(grid, 5);
+
+    // ── Cave ──────────────────────────────────────────────────────────────
+    private static bool[,] GenerateCave(CaGeneratorSettings s, Random rng)
+    {
+        var grid = RandomFill(s.Width, s.Height, s.FillDensity, rng);
+        if (s.BorderWalls) EnforceBorder(grid);
+        for (int i = 0; i < s.SmoothingPasses; i++)
+        {
+            grid = SmoothPass(grid, 5);
+            if (s.BorderWalls) EnforceBorder(grid);
+        }
+        return grid;
+    }
+
+    // ── Platform ──────────────────────────────────────────────────────────
+    private static bool[,] GeneratePlatform(CaGeneratorSettings s, Random rng)
+    {
+        int w = s.Width, h = s.Height;
+        var grid = new bool[w, h];
+
+        for (int x = 0; x < w; x++)
+        {
+            grid[x, h - 1] = true;
+            grid[x, h - 2] = true;
+
+            for (int y = 0; y < h - 2; y++)
+            {
+                // Density linearly increases from 10% at top to 60% at bottom,
+                // scaled by user's FillDensity relative to default 0.48.
+                float t = (float)y / (h - 3);
+                float rowDensity = (0.1f + t * 0.5f) * (s.FillDensity / 0.48f);
+                grid[x, y] = rng.NextDouble() < rowDensity;
+            }
+        }
+
+        for (int i = 0; i < s.SmoothingPasses; i++)
+        {
+            // Threshold 4 (not 5): horizontal platform groups survive, isolated
+            // vertical pixels collapse into flat platforms.
+            grid = SmoothPass(grid, 4);
+            for (int x = 0; x < w; x++) { grid[x, h - 1] = true; grid[x, h - 2] = true; }
+        }
+
+        return grid;
+    }
+
+    // ── Terrain ───────────────────────────────────────────────────────────
+    private static bool[,] GenerateTerrain(CaGeneratorSettings s, Random rng)
+    {
+        int w = s.Width, h = s.Height;
+        var grid = new bool[w, h];
+
+        // Start terrain surface at ~60% from bottom (40% from top)
+        int surfaceRow = (int)(h * 0.4f);
+
+        for (int x = 0; x < w; x++)
+        {
+            int delta = rng.Next(-2, 3);
+            surfaceRow = Math.Clamp(surfaceRow + delta, h / 6, h - 2);
+
+            for (int y = surfaceRow; y < h; y++)
+                grid[x, y] = true;
+        }
+
+        for (int i = 0; i < s.SmoothingPasses; i++)
+            grid = SmoothPass(grid, 5);
+
+        return grid;
+    }
+
+    // ── Shared helpers ────────────────────────────────────────────────
+    private static bool[,] RandomFill(int w, int h, float density, Random rng)
+    {
+        var grid = new bool[w, h];
+        for (int x = 0; x < w; x++)
+            for (int y = 0; y < h; y++)
+                grid[x, y] = rng.NextDouble() < density;
+        return grid;
+    }
+
+    private static bool[,] SmoothPass(bool[,] grid, int threshold)
+    {
+        int w = grid.GetLength(0), h = grid.GetLength(1);
+        var next = new bool[w, h];
+        for (int x = 0; x < w; x++)
+            for (int y = 0; y < h; y++)
+                next[x, y] = CountSolidNeighbors(grid, x, y) >= threshold;
+        return next;
+    }
+
+    private static int CountSolidNeighbors(bool[,] grid, int cx, int cy)
+    {
+        int w = grid.GetLength(0), h = grid.GetLength(1), count = 0;
+        for (int dx = -1; dx <= 1; dx++)
+            for (int dy = -1; dy <= 1; dy++)
+            {
+                if (dx == 0 && dy == 0) continue;
+                int nx = cx + dx, ny = cy + dy;
+                // Out-of-bounds counts as solid (closes cave edges naturally)
+                if (nx < 0 || nx >= w || ny < 0 || ny >= h) count++;
+                else if (grid[nx, ny]) count++;
+            }
+        return count;
+    }
+
+    private static void EnforceBorder(bool[,] grid)
+    {
+        int w = grid.GetLength(0), h = grid.GetLength(1);
+        for (int x = 0; x < w; x++) { grid[x, 0] = true; grid[x, h - 1] = true; }
+        for (int y = 0; y < h; y++) { grid[0, y] = true; grid[w - 1, y] = true; }
+    }
+}