fix #451: stabilize portal seam rendering

src/AcDream.App/Rendering/ParticleRenderer.cs

@@ -47,6 +47,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         public readonly uint ColorArgb;
         public readonly AcDream.App.Rendering.Gpu.GpuTextureSlot TextureSlot;
         public readonly float DistanceSq;
+        public readonly uint ClipSlot;
 
         public ParticleInstance(
             Vector3 position,
@@ -54,7 +55,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             Vector3 axisY,
             uint colorArgb,
             AcDream.App.Rendering.Gpu.GpuTextureSlot textureSlot,
-            float distanceSq)
+            float distanceSq,
+            uint clipSlot)
         {
             Position = position;
             AxisX = axisX;
@@ -62,6 +64,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             ColorArgb = colorArgb;
             TextureSlot = textureSlot;
             DistanceSq = distanceSq;
+            ClipSlot = clipSlot;
         }
     }
 
@@ -80,6 +83,16 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         public Vector4 AxisY;
         public Vector4 Color;
         public uint TextureIndex;
+        public uint ClipSlot;
+    }
+
+    /// <summary>Vertex-instance ABI shared with particle_mesh.vert.</summary>
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct MeshParticleGpuInstance
+    {
+        public Matrix4x4 Model;
+        public Vector4 Color;
+        public uint ClipSlot;
     }
 
     private readonly struct MeshParticleInstance
@@ -87,12 +100,18 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         public readonly Matrix4x4 Model;
         public readonly uint ColorArgb;
         public readonly float DistanceSq;
+        public readonly uint ClipSlot;
 
-        public MeshParticleInstance(Matrix4x4 model, uint colorArgb, float distanceSq)
+        public MeshParticleInstance(
+            Matrix4x4 model,
+            uint colorArgb,
+            float distanceSq,
+            uint clipSlot)
         {
             Model = model;
             ColorArgb = colorArgb;
             DistanceSq = distanceSq;
+            ClipSlot = clipSlot;
         }
     }
 
@@ -124,7 +143,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
     internal (int SetCount, long CapacityBytes) DynamicBufferDiagnostics => (0, 0);
 
     private BillboardGpuInstance[] _instanceScratch = new BillboardGpuInstance[256];
-    private float[] _meshInstanceScratch = new float[256 * 20];
+    private MeshParticleGpuInstance[] _meshInstanceScratch = new MeshParticleGpuInstance[256];
 
     // MP-Alloc (2026-07-05): Draw() is called up to ~11 times per frame
     // (sky pre/post, scene, per-visible-cell, dynamics, unattached passes),
@@ -203,7 +222,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             cameraRight,
             cameraUp,
             emitterFilter,
-            scopedEmitters: null);
+            scopedEmitters: null,
+            clipSlot: 0);
         FinishDraw(camera, renderPass);
     }
 
@@ -213,7 +233,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         ParticleRenderPass renderPass,
         IReadOnlySet<uint> attachedOwnerIds,
         bool includeUnattached = false,
-        IReadOnlySet<uint>? excludedAttachedOwnerIds = null)
+        IReadOnlySet<uint>? excludedAttachedOwnerIds = null,
+        uint clipSlot = 0)
     {
         if (camera is null)
             return;
@@ -233,7 +254,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             cameraRight,
             cameraUp,
             emitterFilter: null,
-            _scopedEmitterScratch);
+            _scopedEmitterScratch,
+            clipSlot);
         FinishDraw(camera, renderPass);
     }
 
@@ -332,7 +354,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         Vector3 cameraRight,
         Vector3 cameraUp,
         Func<AcDream.Core.Vfx.ParticleEmitter, bool>? emitterFilter,
-        IReadOnlyList<RuntimeParticleEmitter>? scopedEmitters)
+        IReadOnlyList<RuntimeParticleEmitter>? scopedEmitters,
+        uint clipSlot)
     {
         var draws = _drawListScratch;
         draws.Clear();
@@ -348,6 +371,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
                     cameraWorldPos,
                     cameraRight,
                     cameraUp,
+                    clipSlot,
                     ref sequence);
             }
             return;
@@ -356,7 +380,13 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         foreach (RuntimeParticleEmitter emitter in _particles.EnumerateRenderableEmitters(renderPass))
         {
             if (emitterFilter is null || emitterFilter(emitter))
-                AppendEmitterDraws(emitter, cameraWorldPos, cameraRight, cameraUp, ref sequence);
+                AppendEmitterDraws(
+                    emitter,
+                    cameraWorldPos,
+                    cameraRight,
+                    cameraUp,
+                    clipSlot,
+                    ref sequence);
         }
     }
 
@@ -365,6 +395,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         Vector3 cameraWorldPos,
         Vector3 cameraRight,
         Vector3 cameraUp,
+        uint clipSlot,
         ref int sequence)
     {
         List<ParticleDraw> draws = _drawListScratch;
@@ -385,7 +416,13 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             uint gfxObjId = em.Desc.HwGfxObjId != 0 ? em.Desc.HwGfxObjId : em.Desc.GfxObjId;
             if (gfxObjId != 0
                 && ResolveGeometryKind(gfxObjId) == RetailParticleGeometryKind.FullMesh
-                && TryAppendMeshDraws(em, p, gfxObjId, cameraWorldPos, ref sequence))
+                && TryAppendMeshDraws(
+                    em,
+                    p,
+                    gfxObjId,
+                    cameraWorldPos,
+                    clipSlot,
+                    ref sequence))
             {
                 continue;
             }
@@ -483,7 +520,8 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
                     axisY,
                     p.ColorArgb,
                     gfxInfo.TextureSlot,
-                    distSq)));
+                    distSq,
+                    clipSlot)));
             _submissionScratch.Add(new ParticleSubmission(
                 ParticleSubmissionKind.Billboard,
                 drawIndex,
@@ -497,6 +535,7 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
         Particle particle,
         uint gfxObjId,
         Vector3 cameraWorldPosition,
+        uint clipSlot,
         ref int sequence)
     {
         if (_meshAdapter is null || !MeshParticlesAvailable)
@@ -520,7 +559,11 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             model,
             cameraWorldPosition);
         float distanceSq = viewerDistance * viewerDistance;
-        var instance = new MeshParticleInstance(model, particle.ColorArgb, distanceSq);
+        var instance = new MeshParticleInstance(
+            model,
+            particle.ColorArgb,
+            distanceSq,
+            clipSlot);
 
         for (int batchIndex = 0; batchIndex < renderData.Batches.Count; batchIndex++)
         {
@@ -581,35 +624,24 @@ public sealed unsafe partial class ParticleRenderer : IDisposable
             TextureIndex = particle.TextureSlot.IsAssigned
                 ? particle.TextureSlot.Index
                 : NoTextureSlot,
+            ClipSlot = particle.ClipSlot,
         };
     }
 
     private static void WriteMeshGpuInstance(
-        float[] destination,
-        int offset,
+        ref MeshParticleGpuInstance destination,
         MeshParticleInstance instance)
     {
-        Matrix4x4 model = instance.Model;
-        destination[offset + 0] = model.M11;
-        destination[offset + 1] = model.M12;
-        destination[offset + 2] = model.M13;
-        destination[offset + 3] = model.M14;
-        destination[offset + 4] = model.M21;
-        destination[offset + 5] = model.M22;
-        destination[offset + 6] = model.M23;
-        destination[offset + 7] = model.M24;
-        destination[offset + 8] = model.M31;
-        destination[offset + 9] = model.M32;
-        destination[offset + 10] = model.M33;
-        destination[offset + 11] = model.M34;
-        destination[offset + 12] = model.M41;
-        destination[offset + 13] = model.M42;
-        destination[offset + 14] = model.M43;
-        destination[offset + 15] = model.M44;
-        destination[offset + 16] = ((instance.ColorArgb >> 16) & 0xFF) / 255f;
-        destination[offset + 17] = ((instance.ColorArgb >> 8) & 0xFF) / 255f;
-        destination[offset + 18] = (instance.ColorArgb & 0xFF) / 255f;
-        destination[offset + 19] = ((instance.ColorArgb >> 24) & 0xFF) / 255f;
+        destination = new MeshParticleGpuInstance
+        {
+            Model = instance.Model,
+            Color = new Vector4(
+                ((instance.ColorArgb >> 16) & 0xFF) / 255f,
+                ((instance.ColorArgb >> 8) & 0xFF) / 255f,
+                (instance.ColorArgb & 0xFF) / 255f,
+                ((instance.ColorArgb >> 24) & 0xFF) / 255f),
+            ClipSlot = instance.ClipSlot,
+        };
     }
 
     private TranslucencyKind ResolveMeshBlend(ObjectRenderBatch batch)