BIM: refactor component area calculation into a helper class
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Furgo
@@ -961,99 +961,21 @@ class Component(ArchIFC.IfcProduct):
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def computeAreas(self,obj):
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"""Compute the area properties of the object's shape.
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Compute the vertical area, horizontal area, and perimeter length of
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the object's shape.
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This function calculates and assigns the following properties to the object:
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- **VerticalArea**: The total area of all vertical faces of the object.
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- **HorizontalArea**: The area of the object's projection onto the XY plane.
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- **PerimeterLength**: The perimeter of the horizontal area.
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The vertical area is the surface area of the faces perpendicular to the
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ground.
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The horizontal area is the area of the shape, when projected onto a
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hyperplane across the XY axes, IE: the area when viewed from a bird's
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eye view.
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The perimeter length is the length of the outside edges of this bird's
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eye view.
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Assign these values to the object's "VerticalArea", "HorizontalArea",
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and "PerimeterLength" properties.
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The function uses the `AreaCalculator` helper class to perform these calculations.
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Refer to that class for more details on the calculation.
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Parameters
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----------
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obj: <App::FeaturePython>
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The component object.
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obj : App::FeaturePython
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The component object whose area properties are to be computed.
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"""
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if (not obj.Shape) or obj.Shape.isNull() or (not obj.Shape.isValid()) or (not obj.Shape.Faces):
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obj.VerticalArea = 0
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obj.HorizontalArea = 0
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obj.PerimeterLength = 0
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return
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import Part
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import DraftGeomUtils
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fmax = params.get_param_arch("MaxComputeAreas")
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if len(obj.Shape.Faces) > fmax:
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obj.VerticalArea = 0
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obj.HorizontalArea = 0
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obj.PerimeterLength = 0
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return
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a = 0
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fset = []
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for i,f in enumerate(obj.Shape.Faces):
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try:
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ang = f.normalAt(0,0).getAngle(FreeCAD.Vector(0,0,1))
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except Part.OCCError:
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print("Debug: Error computing areas for ",obj.Label,": normalAt() Face ",i)
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obj.VerticalArea = 0
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obj.HorizontalArea = 0
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obj.PerimeterLength = 0
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return
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else:
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if ((ang > 1.57) and (ang < 1.571)):
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# Ignore non-planar vertical surfaces for area calculation
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# See https://github.com/FreeCAD/FreeCAD/issues/14687
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if f.Surface.isPlanar():
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a += f.Area
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else:
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fset.append(f)
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if a and hasattr(obj,"VerticalArea"):
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if obj.VerticalArea.Value != a:
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obj.VerticalArea = a
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if fset and hasattr(obj,"HorizontalArea"):
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pset = []
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for f in fset:
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try:
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import TechDraw
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pf = Part.makeFace(DraftGeomUtils.findWires(TechDraw.project(f,FreeCAD.Vector(0,0,1))[0].Edges), "Part::FaceMakerCheese")
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except Part.OCCError:
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# error in computing the areas. Better set them to zero than show a wrong value
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if obj.HorizontalArea.Value != 0:
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print("Debug: Error computing areas for ",obj.Label,": unable to project face: ",str([v.Point for v in f.Vertexes])," (face normal:",f.normalAt(0,0),")")
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obj.HorizontalArea = 0
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if hasattr(obj,"PerimeterLength"):
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if obj.PerimeterLength.Value != 0:
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obj.PerimeterLength = 0
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return
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else:
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pset.append(pf)
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if pset:
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self.flatarea = pset.pop()
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for f in pset:
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self.flatarea = self.flatarea.fuse(f)
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self.flatarea = self.flatarea.removeSplitter()
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if obj.HorizontalArea.Value != self.flatarea.Area:
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obj.HorizontalArea = self.flatarea.Area
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if hasattr(obj,"PerimeterLength") and (len(self.flatarea.Faces) == 1):
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edges_table = {}
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for e in self.flatarea.Edges:
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edges_table.setdefault(e.hashCode(),[]).append(e)
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border_edges = [pair[0] for pair in edges_table.values() if len(pair) == 1]
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obj.PerimeterLength = sum([e.Length for e in border_edges])
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calculator = AreaCalculator(obj)
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calculator.compute()
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def isStandardCase(self,obj):
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"""Determine if the component is a standard case of its IFC type.
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@@ -1189,6 +1111,180 @@ class Component(ArchIFC.IfcProduct):
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return True
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return False
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class AreaCalculator:
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"""Helper class to compute vertical area, horizontal area, and perimeter length.
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This class encapsulates the logic for calculating the following properties:
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- **VerticalArea**: The total area of all vertical faces of the object. See the
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`isFaceVertical` method for the criteria used to determine vertical faces.
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- **HorizontalArea**: The area of the object's projection onto the XY plane.
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- **PerimeterLength**: The perimeter of the horizontal area.
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The class provides methods to validate the object's shape, identify vertical and
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horizontal faces, and compute the required properties.
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"""
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def __init__(self, obj):
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self.obj = obj
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def isShapeInvalid(self):
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"""Check if the object's shape is invalid."""
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return (
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not self.obj.Shape
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or self.obj.Shape.isNull()
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or not self.obj.Shape.isValid()
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or not self.obj.Shape.Faces
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)
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def tooManyFaces(self):
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"""Check if the object's shape has too many faces to process."""
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return len(self.obj.Shape.Faces) > params.get_param_arch("MaxComputeAreas")
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def resetAreas(self):
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"""Reset the area properties of the object to zero. Generally called when
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there is an error.
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"""
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for prop in ["VerticalArea", "HorizontalArea", "PerimeterLength"]:
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setattr(self.obj, prop, 0)
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def isFaceVertical(self, face):
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"""Determine if a face is vertical.
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A face is considered vertical if:
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- Its normal vector forms an angle close to 90 degrees with the Z-axis.
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- The face is planar.
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Notes
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-----
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The check whether the face is planar means that roof-like (sloped) and domed
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faces alike will not be counted as vertical faces. It also means though, that
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vertically-extruded curved edges (for instance from a slab) will also be
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ignored. See also https://github.com/FreeCAD/FreeCAD/issues/14687.
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"""
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from Part import OCCError
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try:
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angle = face.normalAt(0, 0).getAngle(FreeCAD.Vector(0, 0, 1))
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return 1.57 < angle < 1.571 and face.Surface.isPlanar()
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except OCCError:
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FreeCAD.Console.PrintWarning(
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translate("Arch",
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f"Could not determine if a face from {self.obj.Label}"
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" is vertical: normalAt() failed\n")
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)
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return False
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def isFaceHorizontal(self, face):
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"""Determine if a face is horizontal.
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A face is considered horizontal if its normal vector is parallel to the Z-axis.
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"""
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from Part import OCCError
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try:
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angle = face.normalAt(0, 0).getAngle(FreeCAD.Vector(0, 0, 1))
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return angle <= 1.57 or angle >= 1.571
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except OCCError:
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FreeCAD.Console.PrintWarning(
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translate("Arch",
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f"Could not determine if a face from {self.obj.Label}"
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" is horizontal: normalAt() failed\n")
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)
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return False
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def compute(self):
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"""Compute the vertical area, horizontal area, and perimeter length.
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This method performs the following steps:
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1. Identifies the object's vertical and horizontal faces.
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2. Computes the total vertical area by adding areas of all vertical faces.
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3. Projects horizontal faces onto the XY plane and computes their total horizontal area.
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4. Computes the perimeter length of the horizontal area.
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The computed values are assigned to the object's properties:
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- VerticalArea
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- HorizontalArea
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- PerimeterLength
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"""
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if self.isShapeInvalid() or self.tooManyFaces():
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self.resetAreas()
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return
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verticalArea = 0
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horizontalFaces = []
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# Compute vertical area and collect horizontal faces
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for face in self.obj.Shape.Faces:
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if self.isFaceVertical(face):
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verticalArea += face.Area
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elif self.isFaceHorizontal(face):
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horizontalFaces.append(face)
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# Update vertical area
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if verticalArea and hasattr(self.obj, "VerticalArea"):
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if self.obj.VerticalArea.Value != verticalArea:
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self.obj.VerticalArea = verticalArea
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# Compute horizontal area and perimeter length
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if horizontalFaces and hasattr(self.obj, "HorizontalArea"):
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self._computeHorizontalAreaAndPerimeter(horizontalFaces)
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def _computeHorizontalAreaAndPerimeter(self, horizontalFaces):
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"""Compute the horizontal area and perimeter length.
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Projects the given horizontal faces onto the XY plane, fuses them,
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and calculates:
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- The total horizontal area.
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- The perimeter length of the fused horizontal area.
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Parameters
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----------
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horizontalFaces : list of Part.Face
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The horizontal faces to process.
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Notes
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-----
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The operation of projecting faces is done with the `Part::FaceMakerCheese`
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facemaker algorithm, so that holes in the faces are taken into account for
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the area calculation.
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"""
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import Part
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from DraftGeomUtils import findWires
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from TechDraw import project
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projectedFaces = []
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for face in horizontalFaces:
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try:
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projectedEdges = project(face, FreeCAD.Vector(0, 0, 1))[0].Edges
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wires = findWires(projectedEdges)
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projectedFace = Part.makeFace(wires, "Part::FaceMakerCheese")
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projectedFaces.append(projectedFace)
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except Part.OCCError:
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FreeCAD.Console.PrintWarning(
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translate(
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"Arch",
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f"Error computing areas for {self.obj.Label}: unable to project or "
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f"make face with normal {face.normalAt(0, 0)}. "
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"Area values will be reset to 0.\n"
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)
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)
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self.resetAreas()
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return
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if projectedFaces:
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fusedFace = projectedFaces.pop()
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for face in projectedFaces:
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fusedFace = fusedFace.fuse(face)
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fusedFace = fusedFace.removeSplitter()
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if self.obj.HorizontalArea.Value != fusedFace.Area:
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self.obj.HorizontalArea = fusedFace.Area
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if hasattr(self.obj, "PerimeterLength") and len(fusedFace.Faces) == 1:
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edgeTable = {}
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for edge in fusedFace.Edges:
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edgeTable.setdefault(edge.hashCode(), []).append(edge)
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borderEdges = [edges[0] for edges in edgeTable.values() if len(edges) == 1]
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perimeterLength = sum(edge.Length for edge in borderEdges)
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if self.obj.PerimeterLength.Value != perimeterLength:
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self.obj.PerimeterLength = perimeterLength
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class ViewProviderComponent:
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"""A default View Provider for Component objects.
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