add support for single shader per geometry

src/wkb2gltf.core.tests/GlbCreatorTests.cs

@@ -194,6 +194,38 @@ public void CreateGlbWithDegeneratedTriangleShouldNotGiveException()
         Assert.That(bytes, Is.EqualTo(null));
     }
 
+    [Test]
+    public void CreateGlbWithSingleColorShader()
+    {
+        // arrange
+        var wkt = "MULTIPOLYGON Z (((133836.921875 463013.96875 -2.280999898910522,133842.046875 463004.65625 -2.280999898910522,133833.359375 462999.84375 -2.280999898910522,133831.21875 462998.65625 -2.280999898910522,133830.484375 463000 -2.280999898910522,133826.078125 463008.03125 -2.280999898910522,133828.03125 463009.09375 -2.280999898910522,133836.921875 463013.96875 -2.280999898910522)),((133833.359375 462999.84375 2.655999898910522,133833.359375 462999.84375 -2.280999898910522,133842.046875 463004.65625 -2.280999898910522,133842.046875 463004.65625 -0.250999987125397,133833.359375 462999.84375 2.655999898910522)),((133831.21875 462998.65625 0.360000014305115,133831.21875 462998.65625 -2.280999898910522,133833.359375 462999.84375 -2.280999898910522,133833.359375 462999.84375 2.655999898910522,133833.359375 462999.84375 2.776999950408936,133831.21875 462998.65625 0.360000014305115)),((133828.03125 463009.09375 2.638000011444092,133828.03125 463009.09375 2.555000066757202,133830.1875 463005.34375 2.644999980926514,133828.03125 463009.09375 2.638000011444092)),((133833.359375 462999.84375 2.776999950408936,133833.359375 462999.84375 2.655999898910522,133830.1875 463005.34375 2.644999980926514,133833.359375 462999.84375 2.776999950408936)),((133836.921875 463013.96875 -0.331999987363815,133836.921875 463013.96875 -2.280999898910522,133828.03125 463009.09375 -2.280999898910522,133828.03125 463009.09375 2.555000066757202,133828.03125 463009.09375 2.638000011444092,133836.921875 463013.96875 -0.331999987363815)),((133830.484375 463000 0.358999997377396,133830.484375 463000 -2.280999898910522,133831.21875 462998.65625 -2.280999898910522,133831.21875 462998.65625 0.360000014305115,133830.484375 463000 0.358999997377396)),((133842.046875 463004.65625 -0.250999987125397,133842.046875 463004.65625 -2.280999898910522,133836.921875 463013.96875 -2.280999898910522,133836.921875 463013.96875 -0.331999987363815,133842.046875 463004.65625 -0.250999987125397)),((133826.078125 463008.03125 0.354000002145767,133826.078125 463008.03125 -2.280999898910522,133830.484375 463000 -2.280999898910522,133830.484375 463000 0.358999997377396,133826.078125 463008.03125 0.354000002145767)),((133828.03125 463009.09375 2.555000066757202,133828.03125 463009.09375 -2.280999898910522,133826.078125 463008.03125 -2.280999898910522,133826.078125 463008.03125 0.354000002145767,133828.03125 463009.09375 2.555000066757202)),((133842.046875 463004.65625 -0.250999987125397,133836.921875 463013.96875 -0.331999987363815,133828.03125 463009.09375 2.638000011444092,133830.1875 463005.34375 2.644999980926514,133833.359375 462999.84375 2.655999898910522,133842.046875 463004.65625 -0.250999987125397)),((133828.03125 463009.09375 2.555000066757202,133826.078125 463008.03125 0.354000002145767,133830.484375 463000 0.358999997377396,133831.21875 462998.65625 0.360000014305115,133833.359375 462999.84375 2.776999950408936,133830.1875 463005.34375 2.644999980926514,133828.03125 463009.09375 2.555000066757202)))";
+        var g = Geometry.Deserialize<WktSerializer>(wkt);
+        var multipolygon = ((MultiPolygon)g);
+        var shaderColors = new ShaderColors();
+        var metallicRoughness = new PbrMetallicRoughnessColors();
+
+        // use 1 basecolor
+        var random = new Random();
+        var baseColors = new List<string>();
+        var color = string.Format("#{0:X6}", random.Next(0x1000000));
+        baseColors.Add(color);
+
+        metallicRoughness.BaseColors = baseColors;
+
+        shaderColors.PbrMetallicRoughnessColors = metallicRoughness;
+
+        // act
+        var triangles = GeometryProcessor.GetTriangles(multipolygon, 100, new double[] { 0, 0, 0 }, shaderColors);
+        var bytes = GlbCreator.GetGlb(new List<List<Triangle>>() { triangles });
+        var fileName = Path.Combine(TestContext.CurrentContext.WorkDirectory, "ams_building_multiple_colors.glb");
+        File.WriteAllBytes(fileName, bytes);
+
+        var model = ModelRoot.Load(fileName);
+
+        Assert.That(model.LogicalMeshes[0].Primitives.Count, Is.EqualTo(1));
+    }
+
+
     [Test]
     public void CreateGlbWithShader()
     {

src/wkb2gltf.core/ShaderColors.cs

@@ -57,13 +57,19 @@ public void Validate(int expectedGeometries)
 
     private void Check(List<string> colors, int expectedGeometries, string error, List<string> errors)
     {
-        if (colors != null && colors.Count != expectedGeometries) {
+        // check the amount of colors is not null, one or the same as the geometries or 1
+        if (colors != null && colors.Count != expectedGeometries && colors.Count!= 1) {
             errors.Add(error);
         }
     }
 
     private string GetItem(List<string> items, int i)
     {
+        // if there is only one item, always return the first
+        // use for having 1 shader per geometry
+        if(items!=null && items.Count == 1) {
+            i = 0;
+        }
         return items != null ? items[i] : null;
     }
 }

styling.md

@@ -16,7 +16,7 @@ Metallic factor: 0, Roughness factor: 0.5019608 (128/255)
 
 - Alpha: 0 (hardcoded)
 
-Alternative option is to specify a shader per triangle in the ShadersColumn.
+Alternative option is to specify a shader using the ShadersColumn.
 
 Shaderscolumn is a column of type json. In this json document the shaders are defined like PbrMetallicRoughness and
 PbrSpecularGlossiness. Note: PbrSpecularGlossiness is deprecated by Khronos, so advise is to use PbrMetallicRoughness.
@@ -39,9 +39,27 @@ The json must have the following structure:
 }
 ```
 
-The amount of colors in the lists must correspond to the number of triangles in the geometry, otherwise an exception is thrown.
+The amount of colors in the lists 
 
-Warning: The input geometries must be triangulated for this to work. Otherwise pg2b3dm will triangulate the geometries and the number of triangles will be unknown.
+- must correspond to the number of triangles in the geometry;
+
+- or be 1, in which case the same color is used for all triangles in the geometry;
+
+Example:
+
+```
+update delaware_buildings set simple_shader = 
+'{
+    "PbrMetallicRoughness": {
+        "BaseColors": ["#ff0000"]
+    }
+}';
+```
+
+- otherwise an exception is thrown.
+
+
+Warning: When using a shader per triangle, the input geometries must be triangulated for this to work. Otherwise pg2b3dm will triangulate the geometries and the number of triangles will be unknown.
 
 ## Sql