Blender FreeCAD importer stub

io_import_fcstd.py

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#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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# ##### END GPL LICENSE BLOCK #####

bl_info = {
    "name": "FreeCAD Importer",
    "category": "Import-Export",
    "author": "Yorik van Havre",
    "version": (5, 0, 0),
    "blender": (2, 80, 0),
    "location": "File > Import > FreeCAD",
    "description": "Imports a .FCStd file from FreeCAD",
    "warning": "This addon needs FreeCAD installed on your system."
               " Only Part- and Mesh-based objects supported at the moment.",
}

# DESCRIPTION

# This script imports FreeCAD .FCStd files into Blender. This is a work in
# progress, so not all geometry elements of FreeCAD might be suported at
# this point. The development of this addon happens on the FreeCAD forum
# at https://forum.freecadweb.org (no thread yet, please
# create one ;) !)

# WARNING

# This addon requires FreeCAD to be installed on your system.
# A word of warning, your version of FreeCAD must be compiled
# with the same version of python as Blender. The first two
# numbers of the python version must be the same. For example,
# if Blender is using Pyhon 3.7.2, your version of FreeCAD must
# use Python 3.7 too (the third number after 3.7
#
# Once you have a Python3 version of FreeCAD installed, the FreeCAD
# Python module must be known to Blender. There are several ways to obtain
# this:
#
# 1) Set the correct path to FreeCAD.so (or FreeCAD.pyd on windows) in
#    the Addons preferences in user settings, there is a setting for
#    that under the addon panel
#
# 2) Copy or symlink FreeCAD.so (or FreeCAD.pyd on windows) to one of the
#    directories from the list you get when doing this in a Python console:
#
#    import sys; print(sys.path)
#
#    On Debian/Ubuntu and most Linux systems, an easy way to do this is is
#    to symlink FreeCAD.so to your local (user) python modules folder:
#
#    ln -s /path/to/FreeCAD.so /home/YOURUSERNAME/.local/lib/python3.6/site-packages
#
#    (make sure to use the same python version your blender is using instead
#    of 3.6)
#
# 3) A more brutal way if the others fail is to uncomment the following line
#    and set the correct path to where your FreeCAD.so or FreeCAD.pyd resides:
#
#    import sys; sys.path.append("/path/to/FreeCAD.so")
#
# A simple way to test if everything is OK is to enter the following line
# in the Python console of Blender. If no error message appears,
# everything is fine:
#
#    import FreeCAD

# TODO

# support clones + hires
# support texts, dimensions, etc (non-part/mesh objects)

# HISTORY

# v1.0.0 - 12 june 2018 - initial release - basically working
# v2.0.0 - 21 june 2018 - option to turn cycles mat on/off, per-face material support,
#                         use of polygons when possible, shared materials
# v3.0.0 - 06 february 2019 - ported to Blender 2.80
# v4.0.0 - 07 february 2019 - API changes + support of transparency
# v5.0.0 - 13 august 2019 - small fixes and better info messages if things go wrong



import sys, bpy, xml.sax, zipfile, os

from bpy_extras.node_shader_utils import PrincipledBSDFWrapper

TRIANGULATE = False # set to True to triangulate all faces (will loose multimaterial info)

class FreeCAD_xml_handler(xml.sax.ContentHandler):

    """A XML handler to process the FreeCAD GUI xml data"""

    # this creates a dictionary where each key is a FC object name,
    # and each value is a dictionary of property:value pairs

    def __init__(self):

        self.guidata = {}
        self.current = None
        self.properties = {}
        self.currentprop = None
        self.currentval = None

    # Call when an element starts

    def startElement(self, tag, attributes):

        if tag == "ViewProvider":
            self.current = attributes["name"]
        elif tag == "Property":
            name = attributes["name"]
            if name in ["Visibility","ShapeColor","Transparency","DiffuseColor"]:
                self.currentprop = name
        elif tag == "Bool":
            if attributes["value"] == "true":
                self.currentval = True
            else:
                self.currentval = False
        elif tag == "PropertyColor":
            c = int(attributes["value"])
            r = float((c>>24)&0xFF)/255.0
            g = float((c>>16)&0xFF)/255.0
            b = float((c>>8)&0xFF)/255.0
            self.currentval = (r,g,b)
        elif tag == "Integer":
            self.currentval = int(attributes["value"])
        elif tag == "Float":
            self.currentval = float(attributes["value"])
        elif tag == "ColorList":
            self.currentval = attributes["file"]

    # Call when an elements ends

    def endElement(self, tag):

        if tag == "ViewProvider":
            if self.current and self.properties:
                self.guidata[self.current] = self.properties
                self.current = None
                self.properties = {}
        elif tag == "Property":
            if self.currentprop and (self.currentval != None):
                self.properties[self.currentprop] = self.currentval
                self.currentprop = None
                self.currentval = None


def import_fcstd(filename,
                 update=True,
                 placement=True,
                 tessellation=1.0,
                 skiphidden=True,
                 scale=1.0,
                 sharemats=True,
                 report=None):

    """Reads a FreeCAD .FCStd file and creates Blender objects"""

    try:
        # append the FreeCAD path specified in addon preferences
        user_preferences = bpy.context.preferences
        addon_prefs = user_preferences.addons[__name__].preferences
        path = addon_prefs.filepath
        if path:
            if os.path.isfile(path):
                path = os.path.dirname(path)
            print("Configured FreeCAD path:",path)
            sys.path.append(path)
        else:
            print("FreeCAD path is not configured in preferences")
        import FreeCAD
    except:
        print("Unable to import the FreeCAD Python module. Make sure it is installed on your system")
        print("and compiled with Python3 (same version as Blender).")
        print("It must also be found by Python, you might need to set its path in this Addon preferences")
        print("(User preferences->Addons->expand this addon).")
        if report:
            report({'ERROR'},"Unable to import the FreeCAD Python module. Check Addon preferences.")
        return {'CANCELLED'}
    # check if we have a GUI document
    guidata = {}
    zdoc = zipfile.ZipFile(filename)
    if zdoc:
        if "GuiDocument.xml" in zdoc.namelist():
            gf = zdoc.open("GuiDocument.xml")
            guidata = gf.read()
            gf.close()
            Handler = FreeCAD_xml_handler()
            xml.sax.parseString(guidata, Handler)
            guidata = Handler.guidata
            for key,properties in guidata.items():
                # open each diffusecolor files and retrieve values
                # first 4 bytes are the array length, then each group of 4 bytes is abgr
                if "DiffuseColor" in properties:
                    #print ("opening:",guidata[key]["DiffuseColor"])
                    fkey = guidata[key]["DiffuseColor"]
                    if fkey in zdoc.namelist():
                        df = zdoc.open(fkey)
                        buf = df.read()
                        #print (buf," length ",len(buf))
                        df.close()
                        cols = []
                        for i in range(1,int(len(buf)/4)):
                            cols.append((buf[i*4+3],buf[i*4+2],buf[i*4+1],buf[i*4]))
                        guidata[key]["DiffuseColor"] = cols
                    else:
                        print("Wrong DiffuseColor file for object ",key)
                        del guidata[key]["DiffuseColor"]
        zdoc.close()
        #print ("guidata:",guidata)
    doc = FreeCAD.open(filename)
    docname = doc.Name
    if not doc:
        print("Unable to open the given FreeCAD file")
        if report:
            report({'ERROR'},"Unable to open the given FreeCAD file")
        return {'CANCELLED'}
    #print ("Transferring",len(doc.Objects),"objects to Blender")

    # import some FreeCAD modules needed below. After "import FreeCAD" these modules become available
    import Part

    def hascurves(shape):

        for e in shape.Edges:
            if not isinstance(e.Curve,(Part.Line,Part.LineSegment)):
                return True
        return False

    matdatabase = {} # to store reusable materials
    
    fcstd_collection = bpy.data.collections.new("FreeCAD import")
    bpy.context.scene.collection.children.link(fcstd_collection)

    for obj in doc.Objects:
        #print("Importing",obj.Label)
        if skiphidden:
            if obj.Name in guidata:
                if "Visibility" in guidata[obj.Name]:
                    if guidata[obj.Name]["Visibility"] == False:
                        #print(obj.Label,"is invisible. Skipping.")
                        continue

        verts = []
        edges = []
        faces = []
        matindex = [] # face to material relationship
        plac = None
        faceedges = [] # a placeholder to store edges that belong to a face
        name = "Unnamed"

        if obj.isDerivedFrom("Part::Feature"):
            # create mesh from shape
            shape = obj.Shape
            if placement:
                placement = obj.Placement
                shape = obj.Shape.copy()
                shape.Placement = placement.inverse().multiply(shape.Placement)
            if shape.Faces:
                if TRIANGULATE:
                    # triangulate and make faces
                    rawdata = shape.tessellate(tessellation)
                    for v in rawdata[0]:
                        verts.append([v.x,v.y,v.z])
                    for f in rawdata[1]:
                        faces.append(f)
                    for face in shape.Faces:
                        for e in face.Edges:
                            faceedges.append(e.hashCode())
                else:
                    # write FreeCAD faces as polygons when possible
                    for face in shape.Faces:
                        if (len(face.Wires) > 1) or (not isinstance(face.Surface,Part.Plane)) or hascurves(face):
                            # face has holes or is curved, so we need to triangulate it
                            rawdata = face.tessellate(tessellation)
                            for v in rawdata[0]:
                                vl = [v.x,v.y,v.z]
                                if not vl in verts:
                                    verts.append(vl)
                            for f in rawdata[1]:
                                nf = []
                                for vi in f:
                                    nv = rawdata[0][vi]
                                    nf.append(verts.index([nv.x,nv.y,nv.z]))
                                faces.append(nf)
                            matindex.append(len(rawdata[1]))
                        else:
                            f = []
                            ov = face.OuterWire.OrderedVertexes
                            for v in ov:
                                vl = [v.X,v.Y,v.Z]
                                if not vl in verts:
                                    verts.append(vl)
                                f.append(verts.index(vl))
                            # FreeCAD doesn't care about verts order. Make sure our loop goes clockwise
                            c = face.CenterOfMass
                            v1 = ov[0].Point.sub(c)
                            v2 = ov[1].Point.sub(c)
                            n = face.normalAt(0,0)
                            if (v1.cross(v2)).getAngle(n) > 1.57:
                                f.reverse() # inverting verts order if the direction is couterclockwise
                            faces.append(f)
                            matindex.append(1)
                        for e in face.Edges:
                            faceedges.append(e.hashCode())
            for edge in shape.Edges:
                # Treat remaining edges (that are not in faces)
                if not (edge.hashCode() in faceedges):
                    if hascurves(edge):
                        dv = edge.discretize(9) #TODO use tessellation value
                        for i in range(len(dv)-1):
                            dv1 = [dv[i].x,dv[i].y,dv[i].z]
                            dv2 = [dv[i+1].x,dv[i+1].y,dv[i+1].z]
                            if not dv1 in verts:
                                verts.append(dv1)
                            if not dv2 in verts:
                                verts.append(dv2)
                            edges.append([verts.index(dv1),verts.index(dv2)])
                    else:
                        e = []
                        for vert in edge.Vertexes:
                            # TODO discretize non-linear edges
                            v = [vert.X,vert.Y,vert.Z]
                            if not v in verts:
                                verts.append(v)
                            e.append(verts.index(v))
                        edges.append(e)

        elif obj.isDerivedFrom("Mesh::Feature"):
            # convert freecad mesh to blender mesh
            mesh = obj.Mesh
            if placement:
                placement = obj.Placement
                mesh = obj.Mesh.copy() # in meshes, this zeroes the placement
            t = mesh.Topology
            verts = [[v.x,v.y,v.z] for v in t[0]]
            faces = t[1]

        if verts and (faces or edges):
            # create or update object with mesh and material data
            bobj = None
            bmat = None
            if update:
                # locate existing object (mesh with same name)
                for o in bpy.data.objects:
                    if o.data.name == obj.Name:
                        bobj = o
                        print("Replacing existing object:",obj.Label)
            bmesh = bpy.data.meshes.new(name=obj.Name)
            bmesh.from_pydata(verts, edges, faces)
            bmesh.update()
            if bobj:
                # update only the mesh of existing object. Don't touch materials
                bobj.data = bmesh
            else:
                # create new object
                bobj = bpy.data.objects.new(obj.Label, bmesh)
                if placement:
                    #print ("placement:",placement)
                    bobj.location = placement.Base.multiply(scale)
                    m = bobj.rotation_mode
                    bobj.rotation_mode = 'QUATERNION'
                    if placement.Rotation.Angle:
                        # FreeCAD Quaternion is XYZW while Blender is WXYZ
                        q = (placement.Rotation.Q[3],)+placement.Rotation.Q[:3]
                        bobj.rotation_quaternion = (q)
                        bobj.rotation_mode = m
                    bobj.scale = (scale,scale,scale)
                if obj.Name in guidata:
                    if matindex and ("DiffuseColor" in guidata[obj.Name]) and (len(matindex) == len(guidata[obj.Name]["DiffuseColor"])):
                        # we have per-face materials. Create new mats and attribute faces to them
                        fi = 0
                        objmats = []
                        for i in range(len(matindex)):
                            # DiffuseColor stores int values, Blender use floats
                            rgba = tuple([float(x)/255.0 for x in guidata[obj.Name]["DiffuseColor"][i]])
                            # FreeCAD stores transparency, not alpha
                            alpha = 1.0
                            if rgba[3] > 0:
                                alpha = 1.0-rgba[3]
                            rgba = rgba[:3]+(alpha,)
                            bmat = None
                            if sharemats:
                                if rgba in matdatabase:
                                    bmat = matdatabase[rgba]
                                    if not rgba in objmats:
                                        objmats.append(rgba)
                                        bobj.data.materials.append(bmat)
                            if not bmat:
                                if rgba in objmats:
                                    bmat = bobj.data.materials[objmats.index(rgba)]
                            if not bmat:
                                bmat = bpy.data.materials.new(name=obj.Name+str(len(objmats)))
                                bmat.use_nodes = True
                                principled = PrincipledBSDFWrapper(bmat, is_readonly=False)
                                principled.base_color = rgba[:3]
                                if alpha < 1.0:
                                    bmat.diffuse_color = rgba
                                    principled.alpha = alpha
                                    bmat.blend_method = "BLEND"
                                objmats.append(rgba)
                                bobj.data.materials.append(bmat)
                                if sharemats:
                                    matdatabase[rgba] = bmat
                            for fj in range(matindex[i]):
                                bobj.data.polygons[fi+fj].material_index = objmats.index(rgba)
                            fi += matindex[i]
                    else:
                        # one material for the whole object
                        alpha = 1.0
                        rgb = (0.5,0.5,0.5)
                        if "Transparency" in guidata[obj.Name]:
                            if guidata[obj.Name]["Transparency"] > 0:
                                alpha = (100-guidata[obj.Name]["Transparency"])/100.0
                        if "ShapeColor" in guidata[obj.Name]:
                            rgb = guidata[obj.Name]["ShapeColor"]
                        rgba = rgb+(alpha,)
                        bmat = None
                        if sharemats:
                            if rgba in matdatabase:
                                bmat = matdatabase[rgba]
                            else:
                                #print("not found in db:",rgba,"in",matdatabase)
                                pass
                        if not bmat:
                            bmat = bpy.data.materials.new(name=obj.Name)
                            # no more internal engine!
                            # bmat.diffuse_color = rgb
                            # bmat.alpha = alpha
                            #if enablenodes:
                            bmat.use_nodes = True
                            principled = PrincipledBSDFWrapper(bmat, is_readonly=False)
                            principled.base_color = rgb
                            if alpha < 1.0:
                                bmat.diffuse_color = rgba
                            if sharemats:
                                matdatabase[rgba] = bmat
                        bobj.data.materials.append(bmat)

            fcstd_collection.objects.link(bobj)
            #bpy.context.scene.objects.active = obj
            #obj.select = True

    FreeCAD.closeDocument(docname)

    # why is this here? I don't remember. It doesn't seem to work anymore anyway...
    #for area in bpy.context.screen.areas:
    #    if area.type == 'VIEW_3D':
    #        for region in area.regions:
    #            if region.type == 'WINDOW':
    #                override = {'area': area, 'region': region, 'edit_object': bpy.context.edit_object}
    #                bpy.ops.view3d.view_all(override)

    print("Import finished without errors")
    return {'FINISHED'}



#==============================================================================
# Blender Operator class
#==============================================================================


class IMPORT_OT_FreeCAD(bpy.types.Operator):

    """Imports the contents of a FreeCAD .FCStd file"""

    bl_idname = 'import_fcstd.import_freecad'
    bl_label = 'Import FreeCAD FCStd file'
    bl_options = {'REGISTER', 'UNDO'}

    # ImportHelper mixin class uses this
    filename_ext = ".fcstd"

    # Properties assigned by the file selection window.

    directory : bpy.props.StringProperty(maxlen=1024, subtype='FILE_PATH', options={'HIDDEN', 'SKIP_SAVE'})
    files : bpy.props.CollectionProperty(type=bpy.types.OperatorFileListElement, options={'HIDDEN', 'SKIP_SAVE'})
    option_skiphidden : bpy.props.BoolProperty(name="Skip hidden objects", default=True,
        description="Only import objects that where visible in FreeCAD"
    )
    option_update : bpy.props.BoolProperty(name="Update existing objects", default=True,
        description="Keep objects with same names in current scene and their materials, only replace the geometry"
    )
    option_placement : bpy.props.BoolProperty(name="Use Placements", default=True,
        description="Set Blender pivot points to the FreeCAD placements"
    )
    option_tessellation : bpy.props.FloatProperty(name="Tessellation value", default=1.0,
        description="The tessellation value to apply when triangulating shapes"
    )
    option_scale : bpy.props.FloatProperty(name="Scaling value", default=0.001,
        description="A scaling value to apply to imported objects. Default value of 0.001 means one Blender unit = 1 meter"
    )
    option_sharemats : bpy.props.BoolProperty(name="Share similar materials", default=True,
        description="Objects with same color/transparency will use the same material"
    )

    # invoke is called when the user picks our Import menu entry.

    def invoke(self, context, event):
        context.window_manager.fileselect_add(self)
        return {'RUNNING_MODAL'}
    
    # execute is called when the user is done using the modal file-select window.

    def execute(self, context):

        dir = self.directory
        for file in self.files:
            filestr = str(file.name)
            if filestr.lower().endswith(".fcstd"):
                return import_fcstd(filename=dir+filestr,
                                    update=self.option_update,
                                    placement=self.option_placement,
                                    tessellation=self.option_tessellation,
                                    skiphidden=self.option_skiphidden,
                                    scale=self.option_scale,
                                    sharemats=self.option_sharemats,
                                    report=self.report)
        return {'FINISHED'}


class IMPORT_OT_FreeCAD_Preferences(bpy.types.AddonPreferences):


    """A preferences settings dialog to set the path to the FreeCAD module"""

    bl_idname = __name__

    filepath : bpy.props.StringProperty(
            name="Path to FreeCAD.so (Mac/Linux) or FreeCAD.pyd (Windows)",
            subtype='FILE_PATH',
            )

    def draw(self, context):
        layout = self.layout
        layout.label(text="FreeCAD must be installed on your system, and its path set below. Make sure both FreeCAD and Blender use the same Python version (check their Python console)")
        layout.prop(self, "filepath")


#==============================================================================
# Register plugin with Blender
#==============================================================================

classes = (
    IMPORT_OT_FreeCAD,
    IMPORT_OT_FreeCAD_Preferences,
    )

# needed if you want to add into a dynamic menu

def menu_func_import(self, context):

    self.layout.operator(IMPORT_OT_FreeCAD.bl_idname, text="FreeCAD (.FCStd)")


def register():

    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)
    bpy.types.TOPBAR_MT_file_import.append(menu_func_import)


def unregister():

    from bpy.utils import unregister_class
    for cls in reversed(classes):
        unregister_class(cls)
    bpy.types.TOPBAR_MT_file_import.remove(menu_func_import)


if __name__ == "__main__":
    register()

if you like to have a full blender plugin - based on exactly this code here -
have a look at
https://github.com/s-light/io_import_fcstd

Thanks @s-light ! Are you going to try to get it in the official Blender addons list?

oh good question..
i would like it in there! of course!

first i think i have to update it to the current version..
and second is the big issue of how to get to the FreeCAD library module...
(s-light/io_import_fcstd#11)

currently i have no project where i need it -
so my time is very limited on this 🙈

No worries! Maybe someone else will help with that at some point!

Indeed working with AppImages/Snaps/Flatpacks is often a headache when dealing with Python modules... They are basically designed to NOT do what we want: Allow external apps to interact with them :)

If it's not possible to work with a "live" version of the app/snap/flat, something dirty that could be done maybe, is "unzip" it inside some folder and import FreeCAD.so from there...

yeah - that is exactly what i also found: a hacky way but could work:
s-light/io_import_fcstd#11 (comment)

• unsquashfs “snap name”
• myappimage --appimage-extract

no idea what you mean with live - as fare as i know - at least one of the formats get mounted to some special runtime directory -
so if it is running i could search for this and use the libs from there...