This project contains the implementation of 3D Tiles support for SharpGLTF.
The following extensions are supported:
- CESIUM_primitive_outline
- EXT_Mesh_Features
Samples: https://github.com/CesiumGS/3d-tiles-samples/blob/main/glTF/EXT_mesh_features
- EXT_Instance_Features
Specs: https://github.com/CesiumGS/glTF/tree/3d-tiles-next/extensions/2.0/Vendor/EXT_instance_features
Samples: https://github.com/CesiumGS/3d-tiles-samples/tree/main/glTF/GpuInstancesMetadata
- Ext_Structural_Metadata
Samples: https://github.com/CesiumGS/3d-tiles-samples/tree/main/glTF/EXT_structural_metadata
Not supported: External schema and min/max/scale/offset properties for StructuralMetadataClassProperty and PropertyAttributeProperty
The unit test project contains a set of glTF files that are used to test the implementation of the extensions. The glTF files are obtained from https://github.com/CesiumGS/3d-tiles-validator/tree/main/specs/data/gltfExtensions.
See the unit test project for examples of how to write glTF files with the extensions.
The unit tests writes glTF files like the samples from https://github.com/CesiumGS/3d-tiles-samples/tree/main/glTF
For reading glTF files with 3D Tiles extensions the files should be valid according to a validator. The validator is available at https://github.com/CesiumGS/3d-tiles-validator
When writing glTF files with 3D Tiles extensions the resulting files should be valid according to the validator.
Tiles3DExtensions.RegisterExtensions();
var model = ModelRoot.Load("sample.gltf");
var structuralMetadataExtension = model.GetExtension<EXTStructuralMetadataRoot>();
var meshFeaturesExtension = model.LogicalMeshes[0].Primitives[0].GetExtension<MeshExtMeshFeatures>();In the following sample a glTF with 1 triangle is created. The triangle contains metadata with a name column. The name column is set to "this is featureId0". The triangle is assigned featureId 0.
Tiles3DExtensions.RegisterExtensions();
int featureId = 0;
var material = MaterialBuilder.CreateDefault().WithDoubleSide(true);
var mesh = new MeshBuilder<VertexPositionNormal, VertexWithFeatureId, VertexEmpty>("mesh");
var prim = mesh.UsePrimitive(material);
var vt0 = VertexBuilder.GetVertexWithFeatureId(new Vector3(0, 0, 0), new Vector3(0, 0, 1), featureId);
var vt1 = VertexBuilder.GetVertexWithFeatureId(new Vector3(1, 0, 0), new Vector3(0, 0, 1), featureId);
var vt2 = VertexBuilder.GetVertexWithFeatureId(new Vector3(0, 1, 0), new Vector3(0, 0, 1), featureId);
prim.AddTriangle(vt0, vt1, vt2);
var scene = new SceneBuilder();
scene.AddRigidMesh(mesh, Matrix4x4.Identity);
var model = scene.ToGltf2();
var rootMetadata = model.UseStructuralMetadata();
var schema = rootMetadata.UseEmbeddedSchema("schema_001");
var schemaClass = schema.UseClassMetadata("triangles");
var nameProperty = schemaClass
.UseProperty("name")
.WithStringType();
var propertyTable = schemaClass
.AddPropertyTable(1);
propertyTable
.UseProperty(nameProperty)
.SetValues("this is featureId0");
foreach (var primitive in model.LogicalMeshes[0].Primitives)
{
var featureIdAttribute = new FeatureIDBuilder(1, 0, propertyTable);
primitive.AddMeshFeatureIds(featureIdAttribute);
}
model.SaveGLTF(@"sample.gltf");3D Tiles specific parts in the resulting glTF:
"extensions": {
"EXT_structural_metadata": {
"propertyTables": [
{
"class": "triangles",
"count": 1,
"properties": {
"name": {
"stringOffsets": 3,
"values": 2
}
}
}
],
"schema": {
"classes": {
"triangles": {
"properties": {
"name": {
"type": "STRING"
}
}
}
},
"id": "schema_001"
}
}
},
"extensionsUsed": [
"EXT_structural_metadata",
"EXT_mesh_features"
],
"meshes": [
{
"name": "mesh",
"primitives": [
{
"extensions": {
"EXT_mesh_features": {
"featureIds": [
{
"attribute": 0,
"featureCount": 1,
"propertyTable": 0
}
]
}
},
"attributes": {
"POSITION": 0,
"NORMAL": 1,
"_FEATURE_ID_0": 2
},
"indices": 3,
"material": 0
}
]
}
],
Sample loaded in Cesium:
In the following sample a glTF with 2 triangles is created. For visualizing the triangles a texture of a building is used.
A second texture is used containing metadata for storing the metadata values:
-
R channel: Inside temperature
-
G channel: Outside temperature
-
B channel: Humidity
Using a shader in the client application the metadata values can be visualized.
Tiles3DExtensions.RegisterExtensions();
var img0 = "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";
var imageBytes0 = Convert.FromBase64String(img0);
var imageBuilder0 = ImageBuilder.From(imageBytes0);
var img1 = "iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAABLUlEQVR42mVSSxbDIAh0GzUxKZrmCF3n/oerIx9pupgHIswAGtblE7bIKN0vqSOyXSOjPLAtktv9sCFxmcXj7EgsFj8zN00yYxrBZZJBRYk2LdC4WCDUfAdab7bpDm1lCyBW+7lpDnyNS34gcTQRltTPbAeEdFjcSQ0X9EOhGPYjhgLA7xh3kjxEEpMj1qQj7iAzAYoPELzYtuwK02M06WywAFDfX1MdJEoOtSZ7Allz1mYmWZDNL0pNF6ezu9jsQJUcNK7qzbWvMdSYQ8Jo7KKK8/uo4dxreHe0/HgF2/IqBen/za+Di69Sf8cZz5jmk+hcuhdd2tWLz8IE5MbFnRWT+yyU5vZJRtAOqlvq6MDeOrstu0UidsoO0Ak9xGwE+67+34salNEBSCxX7Bexg0rbq6TFvwAAAABJRU5ErkJggg==";
var imageBytes1 = Convert.FromBase64String(img1);
var imageBuilder1 = ImageBuilder.From(imageBytes1);
var material = MaterialBuilder
.CreateDefault()
.WithMetallicRoughnessShader()
.WithBaseColor(imageBuilder0, new Vector4(1, 1, 1, 1))
.WithDoubleSide(true)
.WithAlpha(Materials.AlphaMode.OPAQUE)
.WithMetallicRoughness(0, 1)
.WithMetallicRoughness(imageBuilder1);
var mesh = VBTexture1.CreateCompatibleMesh("mesh");
var prim = mesh.UsePrimitive(material);
prim.AddTriangle(
new VBTexture1(new VertexPosition(0, 0, 0), new Vector2(0, 1)),
new VBTexture1(new VertexPosition(1, 0, 0), new Vector2(1, 1)),
new VBTexture1(new VertexPosition(0, 1, 0), new Vector2(0, 0)));
prim.AddTriangle(
new VBTexture1(new VertexPosition(1, 0, 0), new Vector2(1, 1)),
new VBTexture1(new VertexPosition(1, 1, 0), new Vector2(1, 0)),
new VBTexture1(new VertexPosition(0, 1, 0), new Vector2(0, 0)));
var scene = new SceneBuilder();
scene.AddRigidMesh(mesh, Matrix4x4.Identity);
var model = scene.ToGltf2();
// --------------------------------------------------------------
var rootMetadata = model.UseStructuralMetadata();
var schema = rootMetadata.UseEmbeddedSchema("SimplePropertyTextureSchema");
// define schema
var exampleMetadataClass = schema
.UseClassMetadata("buildingComponents")
.WithName("Building properties");
exampleMetadataClass
.UseProperty("insideTemperature")
.WithName("Inside temperature")
.WithUInt8Type();
exampleMetadataClass
.UseProperty("outsideTemperature")
.WithName("Outside temperature")
.WithUInt8Type();
exampleMetadataClass
.UseProperty("insulation")
.WithName("Insulation Thickness")
.WithUInt8Type()
.WithNormalized(true);
// define texture property
var buildingPropertyTexture = exampleMetadataClass.AddPropertyTexture();
buildingPropertyTexture.CreateProperty("insideTemperature", model.LogicalTextures[1], new int[] { 0 });
buildingPropertyTexture.CreateProperty("outsideTemperature", model.LogicalTextures[1], new int[] { 1 });
buildingPropertyTexture.CreateProperty("insulation", model.LogicalTextures[1], new int[] { 2 });
// assign to primitive
var primitive = model.LogicalMeshes[0].Primitives[0];
primitive.AddPropertyTexture(buildingPropertyTexture);
model.SaveGLTF(@"sample.gltf");3D Tiles specific parts in the resulting glTF:
"extensions": {
"EXT_structural_metadata": {
"propertyTextures": [
{
"class": "buildingComponents",
"properties": {
"insideTemperature": {
"index": 1,
"channels": [
0
]
},
"outsideTemperature": {
"index": 1,
"channels": [
1
]
},
"insulation": {
"index": 1,
"channels": [
2
]
}
}
}
],
"schema": {
"classes": {
"buildingComponents": {
"name": "Building properties",
"properties": {
"insideTemperature": {
"componentType": "UINT8",
"name": "Inside temperature",
"type": "SCALAR"
},
"outsideTemperature": {
"componentType": "UINT8",
"name": "Outside temperature",
"type": "SCALAR"
},
"insulation": {
"componentType": "UINT8",
"name": "Insulation Thickness",
"normalized": true,
"type": "SCALAR"
}
}
}
},
"id": "SimplePropertyTextureSchema"
}
}
},
"meshes": [
{
"name": "mesh",
"primitives": [
{
"extensions": {
"EXT_structural_metadata": {
"propertyTextures": [
0
]
}
},
"attributes": {
"POSITION": 0,
"TEXCOORD_0": 1
},
"indices": 2,
"material": 0
}
]
}
],
Shader code for visualizing the metadata:
// Create a custom (fragment) shader that accesses the metadata value with the
// given property name, normalizes it to a value in [0,1] based on the given
// source range, and uses that value as the brightness for the fragment.
function createShader(propertyName, sourceMin, sourceMax) {
const shader = new Cesium.CustomShader({
fragmentShaderText: `
void fragmentMain(FragmentInput fsInput, inout czm_modelMaterial material)
{
float value = float(fsInput.metadata.${propertyName});
float range = float(${sourceMax}) - float(${sourceMin});
float brightness = (value - float(${sourceMin})) / range;
material.diffuse = vec3(brightness);
}
`,
});
return shader;
}
tileset.customShader = createShader("insideTemperature", 0.0, 255.0);
Sample loaded in Cesium:
