feat(app): render static meshes from Holtburg LandBlockInfo

src/AcDream.App/Rendering/StaticMeshRenderer.cs

@@ -0,0 +1,134 @@
+// src/AcDream.App/Rendering/StaticMeshRenderer.cs
+using System.Numerics;
+using AcDream.Core.Meshing;
+using AcDream.Core.Terrain;
+using AcDream.Core.World;
+using Silk.NET.OpenGL;
+
+namespace AcDream.App.Rendering;
+
+public sealed unsafe class StaticMeshRenderer : IDisposable
+{
+    private readonly GL _gl;
+    private readonly Shader _shader;
+    private readonly TextureCache _textures;
+
+    // One GPU bundle per unique GfxObj id. Each GfxObj can have multiple sub-meshes.
+    private readonly Dictionary<uint, List<SubMeshGpu>> _gpuByGfxObj = new();
+
+    public StaticMeshRenderer(GL gl, Shader shader, TextureCache textures)
+    {
+        _gl = gl;
+        _shader = shader;
+        _textures = textures;
+    }
+
+    public void EnsureUploaded(uint gfxObjId, IReadOnlyList<GfxObjSubMesh> subMeshes)
+    {
+        if (_gpuByGfxObj.ContainsKey(gfxObjId))
+            return;
+
+        var list = new List<SubMeshGpu>(subMeshes.Count);
+        foreach (var sm in subMeshes)
+            list.Add(UploadSubMesh(sm));
+        _gpuByGfxObj[gfxObjId] = list;
+    }
+
+    private SubMeshGpu UploadSubMesh(GfxObjSubMesh sm)
+    {
+        uint vao = _gl.GenVertexArray();
+        _gl.BindVertexArray(vao);
+
+        uint vbo = _gl.GenBuffer();
+        _gl.BindBuffer(BufferTargetARB.ArrayBuffer, vbo);
+        fixed (void* p = sm.Vertices)
+            _gl.BufferData(BufferTargetARB.ArrayBuffer,
+                (nuint)(sm.Vertices.Length * sizeof(Vertex)), p, BufferUsageARB.StaticDraw);
+
+        uint ebo = _gl.GenBuffer();
+        _gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, ebo);
+        fixed (void* p = sm.Indices)
+            _gl.BufferData(BufferTargetARB.ElementArrayBuffer,
+                (nuint)(sm.Indices.Length * sizeof(uint)), p, BufferUsageARB.StaticDraw);
+
+        uint stride = (uint)sizeof(Vertex);
+        _gl.EnableVertexAttribArray(0);
+        _gl.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, stride, (void*)0);
+        _gl.EnableVertexAttribArray(1);
+        _gl.VertexAttribPointer(1, 3, VertexAttribPointerType.Float, false, stride, (void*)(3 * sizeof(float)));
+        _gl.EnableVertexAttribArray(2);
+        _gl.VertexAttribPointer(2, 2, VertexAttribPointerType.Float, false, stride, (void*)(6 * sizeof(float)));
+
+        _gl.BindVertexArray(0);
+
+        return new SubMeshGpu
+        {
+            Vao = vao,
+            Vbo = vbo,
+            Ebo = ebo,
+            IndexCount = sm.Indices.Length,
+            SurfaceId = sm.SurfaceId,
+        };
+    }
+
+    public void Draw(OrbitCamera camera, IEnumerable<WorldEntity> entities)
+    {
+        _shader.Use();
+        _shader.SetMatrix4("uView", camera.View);
+        _shader.SetMatrix4("uProjection", camera.Projection);
+
+        foreach (var entity in entities)
+        {
+            if (entity.MeshRefs.Count == 0)
+                continue;
+
+            foreach (var meshRef in entity.MeshRefs)
+            {
+                if (!_gpuByGfxObj.TryGetValue(meshRef.GfxObjId, out var subMeshes))
+                    continue;
+
+                // model = entity root transform * per-part transform
+                var entityRoot =
+                    Matrix4x4.CreateFromQuaternion(entity.Rotation) *
+                    Matrix4x4.CreateTranslation(entity.Position);
+                var model = meshRef.PartTransform * entityRoot;
+
+                _shader.SetMatrix4("uModel", model);
+
+                foreach (var sub in subMeshes)
+                {
+                    uint tex = _textures.GetOrUpload(sub.SurfaceId);
+                    _gl.ActiveTexture(TextureUnit.Texture0);
+                    _gl.BindTexture(TextureTarget.Texture2D, tex);
+
+                    _gl.BindVertexArray(sub.Vao);
+                    _gl.DrawElements(PrimitiveType.Triangles, (uint)sub.IndexCount, DrawElementsType.UnsignedInt, (void*)0);
+                }
+            }
+        }
+        _gl.BindVertexArray(0);
+    }
+
+    public void Dispose()
+    {
+        foreach (var subs in _gpuByGfxObj.Values)
+        {
+            foreach (var sub in subs)
+            {
+                _gl.DeleteBuffer(sub.Vbo);
+                _gl.DeleteBuffer(sub.Ebo);
+                _gl.DeleteVertexArray(sub.Vao);
+            }
+        }
+        _gpuByGfxObj.Clear();
+    }
+
+    private sealed class SubMeshGpu
+    {
+        public uint Vao;
+        public uint Vbo;
+        public uint Ebo;
+        public int IndexCount;
+        public uint SurfaceId;
+    }
+}