Read provider entity SoA views in Unity

packages/org.gamecult.eve.unity-scene/Runtime/EveUnityEntitySoaView.cs

@@ -0,0 +1,102 @@
+using System;
+using System.Collections.Generic;
+using System.IO.MemoryMappedFiles;
+using System.Linq;
+using GameCult.Eve.Surface;
+using UnityEngine;
+
+#nullable enable
+
+namespace GameCult.Eve.UnityScene
+{
+    public sealed class EveUnityEntitySoaView : IDisposable
+    {
+        private readonly Dictionary<string, MemoryMappedViewAccessor> _buffers =
+            new Dictionary<string, MemoryMappedViewAccessor>(StringComparer.Ordinal);
+        private readonly Dictionary<string, EveEntitySoaColumn> _columns;
+
+        private EveUnityEntitySoaView(EveEntitySoaViewDocument document)
+        {
+            Document = document;
+            _columns = document.Columns.ToDictionary(column => column.Semantic, StringComparer.Ordinal);
+            foreach (var buffer in document.Buffers)
+            {
+                if (!string.Equals(buffer.Backend, "memory_mapped_file", StringComparison.Ordinal))
+                    throw new NotSupportedException($"EveUnity does not support entity SoA backend '{buffer.Backend}'.");
+                var mapped = MemoryMappedFile.OpenExisting(buffer.Location, MemoryMappedFileRights.Read);
+                _buffers.Add(buffer.BufferId, mapped.CreateViewAccessor(
+                    buffer.ByteOffset,
+                    buffer.ByteLength,
+                    MemoryMappedFileAccess.Read));
+                mapped.Dispose();
+            }
+        }
+
+        public EveEntitySoaViewDocument Document { get; }
+        public long Generation => Document.Generation;
+        public IReadOnlyList<EveEntityRenderGroup> RenderGroups => Document.RenderGroups;
+
+        public static EveUnityEntitySoaView Open(EveEntitySoaViewDocument document)
+        {
+            if (document == null) throw new ArgumentNullException(nameof(document));
+            if (!string.Equals(document.Schema, EveEntitySoaViewDocument.SchemaId, StringComparison.Ordinal))
+                throw new ArgumentException($"Expected {EveEntitySoaViewDocument.SchemaId}, got '{document.Schema}'.", nameof(document));
+            return new EveUnityEntitySoaView(document);
+        }
+
+        public bool TryReadVector3(string semantic, int index, out Vector3 value)
+        {
+            value = default;
+            if (!TryColumn(semantic, index, "float32", 12, out var column, out var accessor)) return false;
+            var offset = column.ByteOffset + (long)index * column.ElementStride;
+            value = new Vector3(accessor.ReadSingle(offset), accessor.ReadSingle(offset + 4), accessor.ReadSingle(offset + 8));
+            return true;
+        }
+
+        public bool TryReadFloat(string semantic, int index, out float value)
+        {
+            value = default;
+            if (!TryColumn(semantic, index, "float32", 4, out var column, out var accessor)) return false;
+            value = accessor.ReadSingle(column.ByteOffset + (long)index * column.ElementStride);
+            return true;
+        }
+
+        public bool TryReadInt32(string semantic, int index, out int value)
+        {
+            value = default;
+            if (!TryColumn(semantic, index, "int32", 4, out var column, out var accessor)) return false;
+            value = accessor.ReadInt32(column.ByteOffset + (long)index * column.ElementStride);
+            return true;
+        }
+
+        public bool TryReadByte(string semantic, int index, out byte value)
+        {
+            value = default;
+            if (!TryColumn(semantic, index, "uint8", 1, out var column, out var accessor)) return false;
+            value = accessor.ReadByte(column.ByteOffset + (long)index * column.ElementStride);
+            return true;
+        }
+
+        public void Dispose()
+        {
+            foreach (var accessor in _buffers.Values) accessor.Dispose();
+            _buffers.Clear();
+        }
+
+        private bool TryColumn(
+            string semantic,
+            int index,
+            string scalarType,
+            int minimumStride,
+            out EveEntitySoaColumn column,
+            out MemoryMappedViewAccessor accessor)
+        {
+            column = null!;
+            accessor = null!;
+            if (index < 0 || !_columns.TryGetValue(semantic ?? "", out column)) return false;
+            if (index >= column.ElementCount || column.ElementStride < minimumStride) return false;
+            if (!string.Equals(column.ScalarType, scalarType, StringComparison.Ordinal)) return false;
+            return _buffers.TryGetValue(column.BufferId, out accessor);
+        }
+    }
+}

packages/org.gamecult.eve.unity-scene/Runtime/EveUnityEntitySoaView.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 14693135dfca4740b967148a449cf182
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData:
+  assetBundleName:
+  assetBundleVariant:

packages/org.gamecult.eve.unity-scene/Tests/Editor/EveUnitySceneSurfaceLowererTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO.MemoryMappedFiles;
 using GameCult.Eve.Surface;
 using GameCult.Mesh;
 using NUnit.Framework;
@@ -11,6 +12,45 @@ namespace GameCult.Eve.UnityScene.Tests
 {
     public sealed class EveUnitySceneSurfaceLowererTests
     {
+        [Test]
+        public void EntitySoaViewReadsGenericSemanticColumnsFromAdvertisedBackend()
+        {
+            var location = $"eve-unity-soa-{Guid.NewGuid():N}";
+            using var mapped = MemoryMappedFile.CreateNew(location, 32);
+            using (var writer = mapped.CreateViewAccessor())
+            {
+                writer.Write(0, 4f);
+                writer.Write(4, 5f);
+                writer.Write(8, 6f);
+                writer.Write(12, 7f);
+                writer.Write(16, 8f);
+                writer.Write(20, 9f);
+                writer.Write(24, 41);
+                writer.Write(28, 42);
+            }
+            var document = new EveEntitySoaViewDocument
+            {
+                ProviderId = "provider",
+                ViewId = "pilot",
+                Generation = 7,
+                Backend = "memory_mapped_file",
+                Buffers = new[] { new EveEntitySoaBuffer { BufferId = "hot", Backend = "memory_mapped_file", Location = location, ByteLength = 32, Generation = 7 } },
+                Columns = new[]
+                {
+                    new EveEntitySoaColumn { ColumnId = "position", Semantic = "transform.position", BufferId = "hot", ScalarType = "float32", ElementStride = 12, ElementCount = 2 },
+                    new EveEntitySoaColumn { ColumnId = "entity-index", Semantic = "entity.index", BufferId = "hot", ScalarType = "int32", ByteOffset = 24, ElementStride = 4, ElementCount = 2 }
+                }
+            };
+
+            using var view = EveUnityEntitySoaView.Open(document);
+
+            Assert.That(view.TryReadVector3("transform.position", 1, out var position), Is.True);
+            Assert.That(position, Is.EqualTo(new Vector3(7f, 8f, 9f)));
+            Assert.That(view.TryReadInt32("entity.index", 0, out var entityIndex), Is.True);
+            Assert.That(entityIndex, Is.EqualTo(41));
+            Assert.That(view.Generation, Is.EqualTo(7));
+        }
+
         [Test]
         public void LowerCarriesProviderAdvertisedWorldBoundary()
         {