Geometry brep

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Added pluggable `Brep` support with `compas.geometry.brep`.
+* Added Rhino `Brep` plugin in `compas_rhino.geometry.brep`.
+
 ### Changed
 
 ### Removed

docs/conf.py

@@ -192,7 +192,7 @@ def patched_parse(self):
     self._sections["keys"] = self._parse_keys_section
     self._sections["attributes"] = self._parse_attributes_section
     self._sections["class attributes"] = self._parse_class_attributes_section
-    self._sections["others attributes"] = self._parse_other_attributes_section
+    self._sections["other attributes"] = self._parse_other_attributes_section
     self._unpatched_parse()
 
 

docs/tutorial.rst

@@ -7,6 +7,7 @@ Tutorial
 
     tutorial/data
     tutorial/geometry
+    tutorial/brep
     tutorial/networks
     tutorial/meshes
     tutorial/volmeshes

docs/tutorial/brep.rst

@@ -0,0 +1,150 @@
+***********************
+Boundary Representation
+***********************
+
+.. rst-class:: lead
+
+Boundary representation (Brep) support is realized in COMPAS using its `plugin` system.
+The expected interface for Brep related classes is defined in the :mod:`compas.geometry.brep` module
+whereas the actual implementation is context dependent and implemented using plugins.
+
+.. currentmodule:: compas.geometry
+
+.. highlight:: python
+
+Brep Basics
+===========
+Brep is a data structure used to describe a shape by means of recording topological and geometrical information of the shape's boundaries.
+Some topological properties are associated with an underlying geometry, while others are purely topological.
+
+A Brep is comprised of the following:
+
+.. rst-class:: table table-bordered
+
+.. list-table::
+    :widths: auto
+    :header-rows: 1
+
+    * - Topology
+      - Geometry
+      - Description
+    * - Vertex
+      - 3D Point
+      - The most basic element of a Brep, geometrically described as a point in 3D space.
+    * - Edge
+      - 3D Curve
+      - An edge has a start vertex and an end vertex. The underlying 3D curve describes the geometry of the edge (Line, Circle etc.). Closed edges feature start_vertex == end_vertex.
+    * - Loop
+      - None
+      - A collection of trims which define the inner or outer boundary of a face.
+    * - Face
+      - Surface
+      - Defines the geometry of one of the shape's faces using a surface. Associated with at least one loop which describes the trimmed outer boundary of the surface. Inner loops are referred to as holes in the face.
+    * - Trim
+      - 2D Curve
+      - A 2D curve which trims a face. Trims are associated with a corresponding edge.
+
+
+Getting Started with COMPAS Brep
+================================
+
+To create an empty `Brep`
+
+.. code-block::
+
+    >>> from compas.geometry import Brep
+    >>> brep = Brep()
+
+
+Notice that the type of the actual instance created by `Brep()` will differ depending on the currently available backend.
+For example, when in Rhino
+
+.. code-block::
+
+    >>> type(brep)
+    compas_rhino.geometry.RhinoBrep
+
+Every backend is expected to implement some alternative constructors
+
+.. code-block::
+
+    >>> from compas.geometry import Box
+    >>> from compas.geometry import Brep
+    >>> ...
+    >>> box = Box.from_width_height_depth(5., 5., 5.)
+    >>> brep_box = Brep.from_box(box)
+
+
+`Brep` can also be instantiated from an instance of a backend native `Brep`
+
+.. code-block::
+
+    >>> import Rhino
+    >>> from compas.geometry import Brep
+    >>> ...
+    >>> Brep.from_brep(Rhino.Geometry.Brep())
+
+Brep operations
+===============
+
+Trimming a Brep in Grasshopper
+
+.. code-block::
+
+    from compas.geometry import Frame
+    from compas.geometry import Point
+    from compas.geometry import Brep
+
+    box = Box.from_width_height_depth(5, 5, 10)
+
+    brep = Brep.from_box(box)
+    cutting_plane = Frame(Point(0, 2.5, 0), [1, 0, 0], [0, 1, 1.5])
+
+    brep.trim(cutting_plane)
+
+|pic1| |pic2|
+
+.. |pic1| image:: files/box_w_plane.png
+   :width: 48%
+
+.. |pic2| image:: files/trimmed_box.png
+   :width: 48%
+
+
+Implementing a new backend
+==========================
+
+If you wish to create an additional backend to `Brep` in your package, this can be done using the plugin system of COMPAS.
+
+Create a Brep type in your package which inherits from :class:`compas.geometry.Brep` and override the `__new__` dundle as follows:
+
+.. code-block::
+
+    from compas.geometry import Brep
+
+    class OccBrep(Brep):
+
+        def __new__(cls, *args, **kwargs):
+            # This breaks the endless recursion when calling `compas.geometry.Brep()` and allows
+            # having Brep here as the parent class. Otherwise OccBrep() calls Brep.__new__()
+            # which calls OccBrep() and so on...
+            return object.__new__(cls, *args, **kwargs)
+
+Whenever instantiating `compas.geometry.Brep`, the actual instantiation is delegated to the available factory plugin
+
+.. code-block::
+
+    @plugin(category="factories", requires=["OCC"])
+    def new_brep(*args, **kwargs):
+        # Note: this is called inside Brep.__new__, thus Brep.__init__ will be ran by the interpreter
+        # upon returning from __new__. This means any fully initialized instance returned here will be overwritten!
+        return object.__new__(OccBrep, *args, **kwargs)
+
+Now, a call to `compas.geometry.Brep()` will result in an instance of `your.package.OccBrep`, given that the plugin is available and loaded.
+`OccBrep` encapsulates the native Brep object available by the underlying implementation. If necessary, it can be accessed using `occ_brep_instance.native_brep`.
+
+Implementing the `compas.data.Data` interface
+---------------------------------------------
+A powerful feature of this approach is to be able to serialize a Brep created in one backend and de-serialize it using another.
+For that, it is required that `your.package.OccBrep` implements the :class:`compas.data.Data` interface and follows the unified serialization protocol.
+

src/compas/data/schemas/brep.json

@@ -0,0 +1,13 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "brep.json",
+    "$compas": "1.16.0",
+    "type": "object",
+    "properties": {
+        "faces": {
+            "type": "array",
+            "minItems": 1,
+            "items": {}
+        }
+    }
+}

src/compas/geometry/__init__.py

@@ -74,6 +74,25 @@
     Torus
     Polyhedron
 
+Boundary Representation (Brep)
+------------------------------
+
+.. autosummary::
+    :toctree: generated/
+    :nosignatures:
+
+    Brep
+    BrepVertex
+    BrepEdge
+    BrepLoop
+    BrepFace
+
+    BrepType
+    BrepOrientation
+
+    BrepError
+    BrepInvalidError
+    BrepTrimmingError
 
 Transformations
 ===============
@@ -897,6 +916,21 @@
     NurbsSurface
 )
 
+from .brep import (
+    Brep,
+    BrepVertex,
+    BrepFace,
+    BrepLoop,
+    BrepEdge,
+
+    BrepType,
+    BrepOrientation,
+
+    BrepError,
+    BrepInvalidError,
+    BrepTrimmingError,
+)
+
 __all__ = [
     'close',
     'allclose',
@@ -1201,7 +1235,20 @@
     'NurbsCurve',
 
     'Surface',
-    'NurbsSurface'
+    'NurbsSurface',
+
+    "Brep",
+    "BrepLoop",
+    "BrepEdge",
+    "BrepVertex",
+    "BrepFace",
+
+    "BrepType",
+    "BrepOrientation",
+
+    "BrepError",
+    "BrepInvalidError",
+    "BrepTrimmingError",
 ]
 
 if not compas.IPY:

src/compas/geometry/brep/__init__.py

@@ -0,0 +1,39 @@
+from .brep import Brep
+from .brep import BrepOrientation
+from .brep import BrepType
+from .edge import BrepEdge
+from .loop import BrepLoop
+from .face import BrepFace
+from .vertex import BrepVertex
+
+
+class BrepError(Exception):
+    """Represents a generic error in the Brep context"""
+
+    pass
+
+
+class BrepInvalidError(BrepError):
+    """Raised when the process of re-constructing a Brep has resulted in an invalid Brep"""
+
+    pass
+
+
+class BrepTrimmingError(BrepError):
+    """Raised when a trimming operation has failed or had not result"""
+
+    pass
+
+
+__all__ = [
+    "Brep",
+    "BrepEdge",
+    "BrepLoop",
+    "BrepFace",
+    "BrepVertex",
+    "BrepOrientation",
+    "BrepType",
+    "BrepError",
+    "BrepInvalidError",
+    "BrepTrimmingError",
+]