Support Point Cloud Data (.pcd) for 3D spatial

1. Only support PCD files with PointXYZ format.
2. Not supported for Color or Intensity formats.

QuickLook.Plugin/QuickLook.Plugin.HelixViewer/HelixPanel.Import.cs

@@ -17,6 +17,8 @@
 
 using Assimp;
 using HelixToolkit.Wpf;
+using PcdSharp.IO;
+using PcdSharp.Struct;
 using System;
 using System.IO;
 using System.Linq;
@@ -54,6 +56,86 @@ public partial class HelixPanel
                     modelVisual.Content = model;
                 }
             }
+            if (importerType == ImporterType.Extended_PCD)
+            {
+                // Only support PCD files with PointXYZ format
+                // Not supported for Color or Intensity formats
+                var xyzCloud = PCDReader.Read<PointXYZ>(_path);
+
+                // Create a single geometry for all points to improve performance
+                var pointCloudGeometry = new MeshGeometry3D();
+                var positions = new Point3DCollection();
+                var triangleIndices = new Int32Collection();
+
+                // Create material for points
+                var pointMaterial = new DiffuseMaterial(new SolidColorBrush(Color.FromRgb(0x60, 0x80, 0xFF)));
+
+                // Adaptive point size based on total number of points
+                var totalPoints = xyzCloud.Points.Count;
+                var pointSize = totalPoints > 10000 ? 0.05d : totalPoints > 1000 ? 0.1d : 0.2d;
+
+                // Limit points for performance (show every Nth point if too many)
+                var step = Math.Max(1, totalPoints / 50000); // Limit to ~50k points max
+
+                var vertexIndex = 0;
+                for (int i = 0; i < xyzCloud.Points.Count; i += step)
+                {
+                    var point = xyzCloud.Points[i];
+
+                    // Create a small cube for each point
+                    var halfSize = pointSize / 2;
+
+                    // Add 8 vertices for the cube
+                    var baseIndex = vertexIndex;
+
+                    // Front face vertices
+                    positions.Add(new Point3D(point.X - halfSize, point.Y - halfSize, point.Z + halfSize));
+                    positions.Add(new Point3D(point.X + halfSize, point.Y - halfSize, point.Z + halfSize));
+                    positions.Add(new Point3D(point.X + halfSize, point.Y + halfSize, point.Z + halfSize));
+                    positions.Add(new Point3D(point.X - halfSize, point.Y + halfSize, point.Z + halfSize));
+
+                    // Back face vertices
+                    positions.Add(new Point3D(point.X - halfSize, point.Y - halfSize, point.Z - halfSize));
+                    positions.Add(new Point3D(point.X + halfSize, point.Y - halfSize, point.Z - halfSize));
+                    positions.Add(new Point3D(point.X + halfSize, point.Y + halfSize, point.Z - halfSize));
+                    positions.Add(new Point3D(point.X - halfSize, point.Y + halfSize, point.Z - halfSize));
+
+                    // Add triangle indices for the cube (12 triangles, 36 indices)
+                    // Front face
+                    triangleIndices.Add(baseIndex + 0); triangleIndices.Add(baseIndex + 1); triangleIndices.Add(baseIndex + 2);
+                    triangleIndices.Add(baseIndex + 0); triangleIndices.Add(baseIndex + 2); triangleIndices.Add(baseIndex + 3);
+                    // Back face
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 6); triangleIndices.Add(baseIndex + 5);
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 7); triangleIndices.Add(baseIndex + 6);
+                    // Left face
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 0); triangleIndices.Add(baseIndex + 3);
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 3); triangleIndices.Add(baseIndex + 7);
+                    // Right face
+                    triangleIndices.Add(baseIndex + 1); triangleIndices.Add(baseIndex + 5); triangleIndices.Add(baseIndex + 6);
+                    triangleIndices.Add(baseIndex + 1); triangleIndices.Add(baseIndex + 6); triangleIndices.Add(baseIndex + 2);
+                    // Top face
+                    triangleIndices.Add(baseIndex + 3); triangleIndices.Add(baseIndex + 2); triangleIndices.Add(baseIndex + 6);
+                    triangleIndices.Add(baseIndex + 3); triangleIndices.Add(baseIndex + 6); triangleIndices.Add(baseIndex + 7);
+                    // Bottom face
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 5); triangleIndices.Add(baseIndex + 1);
+                    triangleIndices.Add(baseIndex + 4); triangleIndices.Add(baseIndex + 1); triangleIndices.Add(baseIndex + 0);
+
+                    vertexIndex += 8;
+                }
+
+                pointCloudGeometry.Positions = positions;
+                pointCloudGeometry.TriangleIndices = triangleIndices;
+
+                // Create the model
+                var pointCloudModel = new GeometryModel3D
+                {
+                    Geometry = pointCloudGeometry,
+                    Material = pointMaterial,
+                    BackMaterial = pointMaterial
+                };
+
+                modelVisual.Content = pointCloudModel;
+            }
             else
             {
                 var modelImporter = new ModelImporter();
@@ -90,6 +172,7 @@ file static class Importer
             ".stl" or ".obj" or ".3ds" or ".lwo" or ".ply" => ImporterType.Default,
             ".fbx" or ".3mf" or ".glb" or ".gltf" or ".dae" or ".dxf" => ImporterType.Extended,
             ".pmx" => ImporterType.Extended_MMD,
+            ".pcd" => ImporterType.Extended_PCD,
             _ => ImporterType.Unknown,
         };
     }
@@ -97,8 +180,28 @@ file static class Importer
 
 file enum ImporterType
 {
+    /// <summary>
+    /// Reserved or unspecified import type
+    /// </summary>
     Unknown,
+
+    /// <summary>
+    /// Default importer supported by HelixToolkit
+    /// </summary>
     Default,
+
+    /// <summary>
+    /// Extended importer supported by Assimp
+    /// </summary>
     Extended,
+
+    /// <summary>
+    /// Extended MMD (MikuMikuDance) importer
+    /// </summary>
     Extended_MMD,
+
+    /// <summary>
+    /// Extended PCD (Point Cloud Data) importer for 3D spatial data
+    /// </summary>
+    Extended_PCD,
 }

QuickLook.Plugin/QuickLook.Plugin.HelixViewer/Plugin.cs

@@ -31,17 +31,20 @@ public class Plugin : IViewer
     /// </summary>
     private static readonly HashSet<string> WellKnownExtensions = new(
     [
-        // Default
+        // Default supported by HelixToolkit
         ".stl", ".obj", ".3ds", ".lwo", ".ply",
 
-        // Extended
+        // Extended supported by Assimp
         ".fbx", ".3mf", ".blend", ".glb", ".gltf", ".dae",
 #if S_DXF
         ".dxf",
 #endif
 
-        // Extended_MMD
+        // TBD: MMD (MikuMikuDance)
         //".pmx",
+
+        // PCD (Point Cloud Data)
+        ".pcd",
     ]);
 
     private HelixPanel _hp;

QuickLook.Plugin/QuickLook.Plugin.HelixViewer/QuickLook.Plugin.HelixViewer.csproj

@@ -55,6 +55,7 @@
         <PackageReference Include="HelixToolkit" Version="2.27.0" />
         <PackageReference Include="HelixToolkit.Wpf" Version="2.27.0" />
         <PackageReference Include="AssimpNet" Version="5.0.0-beta1" />
+        <PackageReference Include="PcdSharp" Version="1.0.1" />
     </ItemGroup>
 
     <ItemGroup>