feat: add WorldGenerator filling vertical chunk stacks

VoxelEngine.Tests/WorldGen/WorldGeneratorTests.cs

@@ -0,0 +1,70 @@
+using OpenTK.Mathematics;
+using VoxelEngine.World.Blocks;
+using VoxelEngine.World.Chunk;
+using VoxelEngine.World.WorldGen;
+using Xunit;
+
+namespace VoxelEngine.Tests.WorldGen;
+
+public class WorldGeneratorTests
+{
+    private static BlockRegistry Blocks => new();
+
+    [Fact]
+    public void BlockAt_AboveTerrainAndSea_IsAir()
+    {
+        var blocks = Blocks;
+        var biomes = new BiomeRegistry(1, blocks);
+        ushort id = WorldGenerator.BlockAt(80, surfaceHeight: 70, biomes.Plains, blocks);
+        Assert.Equal(blocks.Air.Id, id); // 80 > 70 and 80 > SeaLevel(64)
+    }
+
+    [Fact]
+    public void BlockAt_AboveTerrainBelowSea_IsWater()
+    {
+        var blocks = Blocks;
+        var biomes = new BiomeRegistry(1, blocks);
+        ushort id = WorldGenerator.BlockAt(60, surfaceHeight: 50, biomes.Plains, blocks);
+        Assert.Equal(blocks.Water.Id, id); // 60 > 50 but 60 <= SeaLevel(64)
+    }
+
+    [Fact]
+    public void BlockAt_Surface_IsBiomeTop()
+    {
+        var blocks = Blocks;
+        var biomes = new BiomeRegistry(1, blocks);
+        ushort id = WorldGenerator.BlockAt(70, surfaceHeight: 70, biomes.Desert, blocks);
+        Assert.Equal(blocks.Sand.Id, id);
+    }
+
+    [Fact]
+    public void BlockAt_FillerBand_IsBiomeFiller()
+    {
+        var blocks = Blocks;
+        var biomes = new BiomeRegistry(1, blocks);
+        ushort id = WorldGenerator.BlockAt(68, surfaceHeight: 70, biomes.Plains, blocks);
+        Assert.Equal(blocks.Dirt.Id, id); // within 3 of surface
+    }
+
+    [Fact]
+    public void BlockAt_Deep_IsStone()
+    {
+        var blocks = Blocks;
+        var biomes = new BiomeRegistry(1, blocks);
+        ushort id = WorldGenerator.BlockAt(40, surfaceHeight: 70, biomes.Plains, blocks);
+        Assert.Equal(blocks.Stone.Id, id);
+    }
+
+    [Fact]
+    public void Generate_IsDeterministic()
+    {
+        var gen1 = new WorldGenerator(99, Blocks);
+        var gen2 = new WorldGenerator(99, Blocks);
+        Chunk a = gen1.Generate(new Vector3i(0, 4, 0));
+        Chunk b = gen2.Generate(new Vector3i(0, 4, 0));
+        for (int x = 0; x < Chunk.Size; x++)
+        for (int y = 0; y < Chunk.Size; y++)
+        for (int z = 0; z < Chunk.Size; z++)
+            Assert.Equal(a[x, y, z], b[x, y, z]);
+    }
+}