add gltf export sample

src/pg2b3dm.slnx

@@ -22,4 +22,7 @@
   <Project Path="pg2b3dm/pg2b3dm.csproj" />
   <Project Path="wkb2gltf.core.tests/wkb2gltf.tests.csproj" />
   <Project Path="wkb2gltf.core/wkb2gltf.csproj" />
+  <Folder Name="/samples/">
+    <Project Path="samples/GltfExport/GltfExport.csproj" />
+  </Folder>
 </Solution>

src/samples/GltfExport/GltfExport.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <AssemblyName>gltfexport</AssemblyName>
+    <RootNamespace>GltfExport</RootNamespace>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CommandLineParser" Version="2.9.1" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.4" />
+    <PackageReference Include="Npgsql" Version="10.0.2" />
+    <PackageReference Include="Wkx" Version="0.5.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\wkb2gltf.core\wkb2gltf.csproj" />
+  </ItemGroup>
+
+</Project>

src/samples/GltfExport/Options.cs

@@ -0,0 +1,40 @@
+using CommandLine;
+using SharpGLTF.Materials;
+
+namespace GltfExport;
+
+public class Options
+{
+    [Option("connection", Required = true, HelpText = "Database connection string.")]
+    public string Connection { get; set; } = string.Empty;
+
+    [Option('o', "output", Required = false, Default = "output", HelpText = "Output directory.")]
+    public string Output { get; set; } = "output";
+
+    [Option('t', "table", Required = true, HelpText = "Database table, include database schema if needed.")]
+    public string Table { get; set; } = string.Empty;
+
+    [Option('c', "column", Required = false, Default = "geom", HelpText = "Geometry column.")]
+    public string GeometryColumn { get; set; } = "geom";
+
+    [Option("shaderscolumn", Required = false, Default = "", HelpText = "Shaders column.")]
+    public string ShadersColumn { get; set; } = string.Empty;
+
+    [Option("idcolumn", Required = false, Default = "id", HelpText = "Id column.")]
+    public string IdColumn { get; set; } = "id";
+
+    [Option("default_color", Required = false, Default = "#FFFFFF", HelpText = "Default color, in RGB(A) order.")]
+    public string DefaultColor { get; set; } = "#FFFFFF";
+
+    [Option("default_metallic_roughness", Required = false, Default = "#008000", HelpText = "Default metallic roughness.")]
+    public string DefaultMetallicRoughness { get; set; } = "#008000";
+
+    [Option("double_sided", Required = false, Default = true, HelpText = "Default double sided.")]
+    public bool DoubleSided { get; set; } = true;
+
+    [Option("default_alpha_mode", Required = false, Default = AlphaMode.OPAQUE, HelpText = "Default glTF material AlphaMode. Other values: BLEND and MASK. Defines how the alpha value is interpreted.")]
+    public AlphaMode DefaultAlphaMode { get; set; } = AlphaMode.OPAQUE;
+
+    [Option("alpha_cutoff", Required = false, Default = 0.5f, HelpText = "Default glTF material AlphaCutoff (used with MASK alpha mode).")]
+    public float AlphaCutoff { get; set; } = 0.5f;
+}

src/samples/GltfExport/Program.cs

@@ -0,0 +1,124 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using CommandLine;
+using Newtonsoft.Json;
+using Npgsql;
+using SharpGLTF.Materials;
+using Wkb2Gltf;
+using Wkx;
+using WkbTriangle = Wkb2Gltf.Triangle;
+
+namespace GltfExport;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        var version = Assembly.GetEntryAssembly()?.GetName().Version;
+        Console.WriteLine($"Tool: GltfExport {version}");
+
+        Parser.Default.ParseArguments<Options>(args).WithParsed(o =>
+        {
+            Console.WriteLine($"Table: {o.Table}");
+            Console.WriteLine($"Geometry column: {o.GeometryColumn}");
+            Console.WriteLine($"Id column: {o.IdColumn}");
+            Console.WriteLine($"Shaders column: {(string.IsNullOrEmpty(o.ShadersColumn) ? "-" : o.ShadersColumn)}");
+            Console.WriteLine($"Output directory: {o.Output}");
+            Console.WriteLine($"Default color: {o.DefaultColor}");
+            Console.WriteLine($"Default metallic roughness: {o.DefaultMetallicRoughness}");
+            Console.WriteLine($"Double sided: {o.DoubleSided}");
+            Console.WriteLine($"Default alpha mode: {o.DefaultAlphaMode}");
+            Console.WriteLine($"Alpha cutoff: {o.AlphaCutoff}");
+
+            Directory.CreateDirectory(o.Output);
+
+            var sql = BuildQuery(o.Table, o.GeometryColumn, o.IdColumn, o.ShadersColumn);
+
+            using var conn = new NpgsqlConnection(o.Connection);
+            conn.Open();
+
+            var cmd = new NpgsqlCommand(sql, conn);
+            var reader = cmd.ExecuteReader();
+
+            var written = 0;
+            var skipped = 0;
+
+            while (reader.Read())
+            {
+                var id = reader.GetFieldValue<object>(0).ToString()!;
+                var safeId = SanitizeFileName(id);
+
+                byte[]? glbBytes = null;
+                try
+                {
+                    var stream = reader.GetStream(1);
+                    var geometry = Geometry.Deserialize<WkbSerializer>(stream);
+
+                    ShaderColors? shaderColors = null;
+                    if (!string.IsNullOrEmpty(o.ShadersColumn))
+                    {
+                        var json = reader.IsDBNull(2) ? null : reader.GetString(2);
+                        if (json != null)
+                        {
+                            shaderColors = JsonConvert.DeserializeObject<ShaderColors>(json);
+                        }
+                    }
+
+                    var record = new GeometryRecord(0) { Geometry = geometry, Shader = shaderColors };
+                    var triangles = record.GetTriangles(translation: null);
+
+                    glbBytes = GlbCreator.GetGlb(
+                        triangles: new List<List<WkbTriangle>> { triangles },
+                        createGltf: true,
+                        defaultColor: o.DefaultColor,
+                        defaultMetallicRoughness: o.DefaultMetallicRoughness,
+                        defaultDoubleSided: o.DoubleSided,
+                        defaultAlphaMode: o.DefaultAlphaMode,
+                        alphaCutoff: o.AlphaCutoff
+                    );
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"Warning: skipping id '{id}': {ex.Message}");
+                    skipped++;
+                    continue;
+                }
+
+                if (glbBytes == null)
+                {
+                    Console.WriteLine($"Warning: skipping id '{id}': no geometry produced.");
+                    skipped++;
+                    continue;
+                }
+
+                var outputFile = Path.Combine(o.Output, $"{safeId}.glb");
+                File.WriteAllBytes(outputFile, glbBytes);
+                written++;
+            }
+
+            reader.Close();
+            conn.Close();
+
+            Console.WriteLine($"Done. Written: {written}, Skipped: {skipped}.");
+        });
+    }
+
+    private static string BuildQuery(string table, string geomColumn, string idColumn, string shadersColumn)
+    {
+        var select = $"SELECT {idColumn}::text, ST_AsBinary({geomColumn})";
+        if (!string.IsNullOrEmpty(shadersColumn))
+        {
+            select += $", {shadersColumn}";
+        }
+        return $"{select} FROM {table}";
+    }
+
+    private static string SanitizeFileName(string name)
+    {
+        var invalid = Path.GetInvalidFileNameChars();
+        return string.Concat(name.Select(c => invalid.Contains(c) ? '_' : c));
+    }
+}

src/samples/GltfExport/README.md

@@ -0,0 +1,58 @@
+# GltfExport
+
+A .NET 8.0 console tool that exports PostGIS geometries as individual glTF 2.0 (`.glb`) files — one file per row, named `{id}.glb`.
+
+Geometry coordinates are used **as-is** (no translation or reprojection is applied).
+
+## Requirements
+
+- .NET 8.0 SDK
+- A PostgreSQL database with PostGIS extension
+- A table containing a geometry column and an id column
+
+## Usage
+
+```bash
+gltfexport --connection "Host=localhost;Database=mydb;Username=myuser;Password=mypassword" \
+           -t myschema.mytable \
+           -o ./output
+```
+
+## Parameters
+
+| Parameter | Short | Required | Default | Description |
+|---|---|---|---|---|
+| `--connection` | | Yes | | PostgreSQL connection string |
+| `--table` | `-t` | Yes | | Database table (include schema if needed, e.g. `public.buildings`) |
+| `--output` | `-o` | No | `output` | Output directory for `.glb` files |
+| `--column` | `-c` | No | `geom` | Geometry column |
+| `--idcolumn` | | No | `id` | Id column — used as the output filename |
+| `--shaderscolumn` | | No | *(empty)* | Shaders column (JSON with PBR material colors) |
+| `--default_color` | | No | `#FFFFFF` | Default color in RGB(A) order |
+| `--default_metallic_roughness` | | No | `#008000` | Default metallic roughness |
+| `--double_sided` | | No | `true` | Double-sided rendering |
+| `--default_alpha_mode` | | No | `OPAQUE` | glTF AlphaMode: `OPAQUE`, `BLEND`, or `MASK` |
+| `--alpha_cutoff` | | No | `0.5` | Alpha cutoff value (used with `MASK` alpha mode) |
+| `--help` | | | | Display help |
+| `--version` | | | | Display version information |
+
+## Output
+
+Each row in the table produces one `.glb` file in the output directory, named after the value in the id column (invalid filename characters are replaced with `_`).
+
+## Example
+
+Given a table `public.buildings` with columns `gid` (integer), `geom` (geometry), and `shader` (json):
+
+```bash
+gltfexport \
+  --connection "Host=localhost;Database=citydb;Username=postgres" \
+  -t public.buildings \
+  -c geom \
+  --idcolumn gid \
+  --shaderscolumn shader \
+  --default_color "#CCCCCC" \
+  -o ./glb_output
+```
+
+This produces files like `./glb_output/1.glb`, `./glb_output/2.glb`, etc.