Gents, Just want to express my support regarding these activities! Great, great work!
2009/7/5 Thomas Paviot <tpav...@gmail.com>: > Hi all, > > Based on the SalomeGEOM library, which was included a few weeks ago in > pythonOCC (see the subversion trunk), a pure python prametric framework is > currently being (actively) developped. > > This parametric framework is based on four main classes: > - the Parameter class: creation of parameters, > - the Facotry class: creation of geometry based on the parameters, > - the Rule class: enable to attach one or more rules to a Parameter. The > rule consists of a function that returns a boolean: True if the rule is > validated, false otherwise, > - the Relation class: create relations between parameters. This class is > based on sympy (http://code.google.com/p/sympy/), a Python library for > symbolic mathematics. > > Then, each time a parameter is changed (which can be done from a ipython > -wthread interactive console): > - the new values of parameters are computed according to the different > Relations that have been set up, > - the Rules are checked. > > It's not finished yet, and the result has not yet been uploaded to the > subversion trunk, but it should be done in a few days (weeks?), once the API > is stable (it's still moving almost every day). It's mostly based on python > descriptors (http://users.rcn.com/python/download/Descriptor.htm), with an > intensive use of callbacks and operator overloading. Of course, thanks to > the magic of Python, this framework is currently only 500 lines of > pythoncode. > > Although it's not available yet, here is a small sample I made, called the > 'gears' sample. The diameter of the gears and the relative position are > driven by two parameters: the velocity ratio (r) and the distance between > axis (a). Every change in those parameters modifies the geometry in > consequence, if the rules are validated. The syntax could change in the > future, but the architecture is defined and should be stable. > > The work that still have to be done: > - simplify the API (there's still a possible confusion with the handle of > parameters by strings "p.X" or attributes p.X), > - check the stability of the API, in case, for instance, of cyclic > references between parameters, > - and, in a mid term, link this framework with solvers (constraint > programming, evolutionary computing etc.) in order to find solutions to > engineering problems as defined by the (Rules,Relations). > > Of course, I'll let you know about the future developments of this project. > > Best Regards, > > Thomas > > ##Copyright 2009 Thomas Paviot (tpav...@gmail.com) > ## > ##This file is part of pythonOCC. > ## > ##pythonOCC 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 3 of the License, or > ##(at your option) any later version. > ## > ##pythonOCC 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 pythonOCC. If not, see <http://www.gnu.org/licenses/>. > > # A sample that shows how to generate the gear geometry according > # to knowledge > > from Context import Context > import Parametric > from Parametric import Parameters, symb, Relation > import Factory > import Presentation > from math import pi > from sympy import * > > # > # Initialization > # > my_context = Context() > my_context.Init() > my_presentation = Presentation.Presentation(my_context) > p = Parameters(my_context) > p.register_callback(my_presentation.update) #tells that viewer should be > updated after each parameter modification > my_factory = Factory.Factory(my_context) > > # > # Define the first gear (actually modelized by a cylinder) > # > > # location of the first gear > p.X1 = 0.0 > p.Y1 = 0.0 > p.Z1 = 0.0 > my_pnt1 = my_factory.PointXYZ(p.X1,p.Y1,p.Z1,"Pnt1") > # Direction of the gear > p.DX1 = 0.0 > p.DY1 = 0.0 > p.DZ1 = 1.0 > my_vec1 = my_factory.VectorDXDYDZ(p.DX1,p.DY1,p.DZ1,"Vec1") > # Parameters of the cylinder > p.R1 = 50.0 #radius > p.H1 = 20.0 #height > p.Angle1 = 0.0 > gear1 = > my_factory.CylinderPntVecRH(my_pnt1,my_vec1,p.R1,p.H1,p.Angle1,"Gear1") > > # > # Define the second gear (actually also modelized by a cylinder) > # > > # location of the second gear > p.X2 = 100 > p.Y2 = 0.0 > p.Z2 = 0.0 > my_pnt2 = my_factory.PointXYZ(p.X2,p.Y2,p.Z2,"Pnt2") > # Direction of the second gear > p.DX2 = 0.0 > p.DY2 = 0.0 > p.DZ2 = 1.0 > my_vec2 = my_factory.VectorDXDYDZ(p.DX2,p.DY2,p.DZ2,"Vec2") > # Parameters of the second cylinder > p.R2 = 70.0 #radius > p.H2 = 20.0 #height > p.Angle2 = 0.0 > gear2 = > my_factory.CylinderPntVecRH(my_pnt2,my_vec2,p.R2,p.H2,p.Angle2,"Gear2") > > # Displays gears > my_presentation.register_object(gear1) > my_presentation.register_object(gear2,color=1) > > # Define the parameters that drive the design of the gears > p.m = 2 #the gear modulus > p.a= 100 # the distance between gears axis > # Other parameters of the gears that it's good to know about > p.Z1 = 1 #unknown for the moment, the parameter is just created > p.Z2 = 1 # number of teeth, unknown for the moment > p.r = 0.5 # The speed ratio > > def DefineRules(): > # The number of teeth must be greater than 0 and also be an integer > def CheckZ(Z): > return (int(Z)/Z==1.0 and Z>0) > R1 = Parametric.Rule(p,"Z1",CheckZ) > R2 = Parametric.Rule(p,"Z2",CheckZ) > # The modulus cannot take any value #notice that this list is not > exhaustive. > def Checkm(m): > return m in [0.06,0.08,0.1,1,1.25,1.5,2,2.5,3] > R3 = Parametric.Rule(p,"m",Checkm) > > def DefineRelations(): > # The three relations are: > # * d1 = 2a/(1+r) so R1=a/(1+r) (Rel1) > # * d2 = 2ar(1+r) so R2 = ar/(1+r) (Rel2) > # * p.X2 = p.X1 + p.a (Rel3) > # define a sympy relation based on one parameter > r = symb(p.r) > a = symb(p.a) > X1 = symb(p.X1) > Rel1 = a/(1+r) > Rel2 = a*r/(1+r) > Rel3 = X1 + a > Relation(p,"R1",Rel1) > Relation(p,"R2",Rel2) > Relation(p,"X2",Rel3) > > DefineRules() > DefineRelations() > > > _______________________________________________ > Pythonocc-users mailing list > Pythonocc-users@gna.org > https://mail.gna.org/listinfo/pythonocc-users > > _______________________________________________ Pythonocc-users mailing list Pythonocc-users@gna.org https://mail.gna.org/listinfo/pythonocc-users
