Incomplete experimental glTF exporter

src/build123d/__init__.py

@@ -20,6 +20,7 @@
 from build123d.topology import *
 from build123d.drafting import *
 from build123d.persistence import modify_copyreg
+from build123d.exporters3d import *
 
 from .version import version as __version__
 
@@ -207,4 +208,7 @@
     # Topology Exploration
     "topo_explore_connected_edges",
     "topo_explore_common_vertex",
+    # 3D Exporters
+    "export_step_alt",
+    "export_gltf",
 ]

src/build123d/exporters3d.py

@@ -30,20 +30,28 @@
 
 import OCP.TopAbs as ta
 from anytree import PreOrderIter
+from OCP.BRepMesh import BRepMesh_IncrementalMesh
+from OCP.BRepTools import BRepTools
 from OCP.IFSelect import IFSelect_ReturnStatus
 from OCP.IGESControl import IGESControl_Controller
 from OCP.Interface import Interface_Static
+from OCP.Message import Message_ProgressRange
+from OCP.RWGltf import RWGltf_CafWriter
 from OCP.STEPCAFControl import STEPCAFControl_Controller, STEPCAFControl_Writer
 from OCP.STEPControl import STEPControl_Controller, STEPControl_StepModelType
-from OCP.TCollection import TCollection_ExtendedString
+from OCP.TCollection import TCollection_ExtendedString, TCollection_AsciiString
+from OCP.TColStd import TColStd_IndexedDataMapOfStringString
 from OCP.TDataStd import TDataStd_Name
+from OCP.TDF import TDF_Label
 from OCP.TDocStd import TDocStd_Document
 from OCP.TopExp import TopExp_Explorer
 from OCP.XCAFApp import XCAFApp_Application
 from OCP.XCAFDoc import XCAFDoc_ColorType, XCAFDoc_DocumentTool
 from OCP.XSControl import XSControl_WorkSession
 
-from build123d import Compound, Curve, Part, Shape, Sketch, Unit
+from build123d.build_enums import Unit
+from build123d.geometry import Location
+from build123d.topology import Compound, Curve, Part, Shape, Sketch
 
 
 class PrecisionMode(Enum):
@@ -65,33 +73,27 @@ def __repr__(self):
         return f"<{self.__class__.__name__}.{self.name}>"
 
 
-def export_step_with_color_label(
-    to_export: Shape,
-    path: str,
-    unit: Unit = Unit.MM,
-    write_pcurves: bool = True,
-    precision_mode: PrecisionMode = PrecisionMode.AVERAGE,
-) -> bool:
-    """export_step
+def _create_xde(to_export: Shape, unit: Unit = Unit.MM) -> TDocStd_Document:
+    """create_xde
 
-    Export a build123d Shape or assembly with color and label attributes.
-    Note that if the color of a node in an assembly isn't set, it will be
-    assigned the color of its nearest ancestor.
+    An OpenCASCADE Technology (OCCT) XDE (eXtended Data Exchange) document is a
+    sophisticated framework designed for comprehensive CAD data management,
+    facilitating not just the geometric modeling of shapes but also the handling
+    of associated metadata, such as material properties, color, layering, and
+    annotations. This integrated environment supports the organization and
+    manipulation of complex assemblies and parts, enabling users to navigate,
+    edit, and query both the structure and attributes of CAD models. XDE's
+    architecture is particularly beneficial for applications requiring detailed
+    interoperability between different CAD systems, offering robust tools for
+    data exchange, visualization, and modification while preserving the integrity
+    and attributes of the CAD data across various stages of product development.
 
     Args:
         to_export (Shape): object or assembly
-        path (str): step file path
         unit (Unit, optional): shape units. Defaults to Unit.MM.
-        write_pcurves (bool, optional): write parametric curves to the STEP file.
-            Defaults to True.
-        precision_mode (bool, optional): geometric data precision.
-            Defaults to PrecisionMode.AVERAGE.
-
-    Raises:
-        RuntimeError: Unknown Compound type
 
     Returns:
-        bool: success
+        TDocStd_Document: XDE document
     """
     # Create the XCAF document
     doc = TDocStd_Document(TCollection_ExtendedString("XmlOcaf"))
@@ -117,6 +119,7 @@ def export_step_with_color_label(
     # Get the tools for handling shapes & colors section of the XCAF document.
     shape_tool = XCAFDoc_DocumentTool.ShapeTool_s(doc.Main())
     color_tool = XCAFDoc_DocumentTool.ColorTool_s(doc.Main())
+    # shape_tool.SetAutoNaming_s(True)
 
     # Add all the shapes in the b3d object either as a single object or assembly
     is_assembly = isinstance(to_export, Compound) and len(to_export.children) > 0
@@ -145,8 +148,7 @@ def export_step_with_color_label(
                 raise RuntimeError("Unknown Compound type")
 
             while explorer.More():
-                current_shape = explorer.Current()
-                sub_nodes.append(current_shape)
+                sub_nodes.append(explorer.Current())
                 explorer.Next()
 
             sub_node_labels = [
@@ -176,8 +178,44 @@ def export_step_with_color_label(
                 )
 
     shape_tool.UpdateAssemblies()
+
     # print(f"Is document valid: {XCAFDoc_DocumentTool.IsXCAFDocument_s(doc)}")
 
+    return doc
+
+
+def export_step_alt(
+    to_export: Shape,
+    path: str,
+    unit: Unit = Unit.MM,
+    write_pcurves: bool = True,
+    precision_mode: PrecisionMode = PrecisionMode.AVERAGE,
+) -> bool:
+    """export_step
+
+    Export a build123d Shape or assembly with color and label attributes.
+    Note that if the color of a node in an assembly isn't set, it will be
+    assigned the color of its nearest ancestor.
+
+    Args:
+        to_export (Shape): object or assembly
+        path (str): step file path
+        unit (Unit, optional): shape units. Defaults to Unit.MM.
+        write_pcurves (bool, optional): write parametric curves to the STEP file.
+            Defaults to True.
+        precision_mode (bool, optional): geometric data precision.
+            Defaults to PrecisionMode.AVERAGE.
+
+    Raises:
+        RuntimeError: Unknown Compound type
+
+    Returns:
+        bool: success
+    """
+
+    # Create the XCAF document
+    doc = _create_xde(to_export, unit)
+
     session = XSControl_WorkSession()
     writer = STEPCAFControl_Writer(session, False)
     writer.SetColorMode(True)
@@ -206,6 +244,89 @@ def export_step_with_color_label(
     Interface_Static.SetIVal_s("write.precision.mode", precision_mode.value)
     writer.Transfer(doc, STEPControl_StepModelType.STEPControl_AsIs)
 
-    status = writer.Write(path)
+    status = writer.Write(path) == IFSelect_ReturnStatus.IFSelect_RetDone
+
+    if not status:
+        raise RuntimeError("Failed to write glTF file")
+
+    return status
+
+
+def export_gltf(
+    to_export: Shape,
+    path: str,
+    unit: Unit = Unit.MM,
+    binary: bool = False,
+    linear_deflection: float = 0.001,
+    angular_deflection: float = 0.1,
+) -> bool:
+    """export_gltf
+
+    The glTF (GL Transmission Format) specification primarily focuses on the efficient
+    transmission and loading of 3D models as a compact, binary format that is directly
+    renderable by graphics APIs like WebGL, OpenGL, and Vulkan. It's designed to store
+    detailed 3D model data, including meshes (vertices, normals, textures, etc.),
+    animations, materials, and scene hierarchy, among other aspects.
+
+    Args:
+        to_export (Shape): object or assembly
+        path (str): glTF file path
+        unit (Unit, optional): shape units. Defaults to Unit.MM.
+        binary (bool, optional): output format. Defaults to False.
+        linear_deflection (float, optional): A linear deflection setting which limits
+            the distance between a curve and its tessellation. Setting this value too
+            low will result in large meshes that can consume computing resources. Setting
+            the value too high can result in meshes with a level of detail that is too
+            low. The default is a good starting point for a range of cases.
+            Defaults to 1e-3.
+        angular_deflection (float, optional): Angular deflection setting which limits
+            the angle between subsequent segments in a polyline. Defaults to 0.1.
+
+    Raises:
+        RuntimeError: Tessellation failed
+        RuntimeError: Failed to write glTF file
+
+    Returns:
+        bool: write status
+    """
+
+    # map from OCCT's right-handed +Z up coordinate system to glTF's right-handed +Y up coordinate system
+    # https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#coordinate-system-and-units
+    original_location = to_export.location
+    to_export.location *= Location((0, 0, 0), (1, 0, 0), -90)
+
+    # Tessellate the object(s)
+    mesh_tool = BRepMesh_IncrementalMesh(
+        to_export.wrapped, linear_deflection, True, angular_deflection, True
+    )
+    mesh_tool.Perform()
+
+    # Check Tessellation
+    node: Shape
+    for node in PreOrderIter(to_export):
+        explorer = TopExp_Explorer(node.wrapped, ta.TopAbs_FACE)
+        while explorer.More():
+            face = explorer.Current()
+            if not BRepTools.Triangulation_s(face, linear_deflection):
+                raise RuntimeError("Tessellation failed")
+            explorer.Next()
+
+    # Create the XCAF document
+    doc: TDocStd_Document = _create_xde(to_export, unit)
+
+    # Write the glTF file
+    writer = RWGltf_CafWriter(theFile=TCollection_AsciiString(path), theIsBinary=binary)
+    index_map = TColStd_IndexedDataMapOfStringString()
+    progress = Message_ProgressRange()
+    status = writer.Perform(doc, index_map, progress)
+
+    # Reset tessellation
+    BRepTools.Clean_s(to_export.wrapped)
+
+    # Reset original orientation
+    to_export.location = original_location
+
+    if not status:
+        raise RuntimeError("Failed to write glTF file")
 
-    return status == IFSelect_ReturnStatus.IFSelect_RetDone
+    return status