Re: [Pythoncad-developer] Draw in oo mode

[Paolo Z. <zam...@gm...>]

Hi Gertwin,
        
        The design is not a puzzle surfaces.
        Design is an overlap of surfaces.
        
        >You need to have a kind of way to
        > describe the surface.
        
        A closed path is one and only one surface.
        I have attached a svg file with examples.
        
        I do not know GEOS.
        PyCairo is good!. Draw surfaces one above the other
        
        > Besides only surfaces, a cad drawing must contain simple
        linear
        > entities, for instance lines can make up a sewerage system, by
        binding
        > properties to this line like diameter and material it becomes
        an
        > (linear) object.
        
        If not a path then it is annotation (axsis, dimension,...)
        
        I thought the following classes:
        
        class sketch(): factory of path
               .
               .
               self._entities=[] # serialized in DB
               .
               .
               def get_path(self)
               .
               .
               return path #continually recalculated
        
        
        class path():
               .
               .
               self._entities=[] # referece in DB
               .
               def get_entity(self,n)
               .
               .
               return path #continually recalculated
        
        
        class Function():
               .
               .
               self._input_paths=[] # referece in DB
               .
               .
               def get_output_paths(self)
               .
               .
               return paths #continually recalculated
        
               def set_position(self,path,n)
               def set_rotation(self,patth,n,a)
               def translate(self,x,y)
               def rotate(a)
        
        
        class Projection():
               .
               .
               self._Functions=[] # references in DB
        
               def set_position(self,path,n)
               def set_rotation(self,patth,n,a)
               def translate(self,x,y)
               def rotate(a)
               .
               .
        
        class Drawing():
               .
               .
               self._projections=[] # references in DB
               self._annotations=[] # references in DB
        
               def get_image(self) #continually recalculated
        
        Regards,
        Paolo
        
        

Il giorno lun, 17/05/2010 alle 21.37 +0200, Gertwin Groen ha scritto:
> Hi Paolo,
> 
> I think your ideas about surfaces are interesting.
> This is how I see this subject, correct me if I am wrong.
> 
> As you said the boundary of the surfaces are made up from simple
> linear entities or circles, ellipses.
> We need functions to create and manipulate simple linear boundary entities.
> 
> A single boundary entity can serve as edge between 2 surfaces, moving
> this single entity modifies 2 surfaces.
> Because entities can act as a boundary between multiple surfaces,
> these boundary entities itself can not identify the surface object.
> For instance a single line entity can act as the boundary between the
> street and a building, this line can not say anything about the
> surfaces to the left and right. You need to have a kind of way to
> describe the surface.
> 
> On the other way not all linear entities can act as an boundary for surfaces.
> If you have an floor with an table, the table must not result in an
> island on the floor.
> So the boundary of the table is not used for the floor.
> 
> I think all the actions on surfaces (or polygons) that you describes
> are handled by the GEOS (http://trac.osgeo.org/geos/) project.
> See the methods of the GEOMETRY object:
> http://download.osgeo.org/geos/doxygen/classgeos_1_1geom_1_1Geometry.html.
> 
> I agree with you that we need a good set of functions to describe
> surface objects.
> Matteo and I had some discussion about this a while ago.
> 
> Besides only surfaces, a cad drawing must contain simple linear
> entities, for instance lines can make up a sewerage system, by binding
> properties to this line like diameter and material it becomes an
> (linear) object.
> 
> Regards,
> Gertwin
> 
> 
> 2010/5/15 Paolo Zambetti <zam...@gm...>:
> >
> > Hi developers,
> >
> > Let read the follow idea!
> >
> > Some days ago I bring my chief a draw, and he told me: “next time it’s
> > better if you bring me a white paper with some random lines on it, so I
> > can fix them on it!”. All times I mind about a list of entities in a
> > document I ask myself: Now who does fix them?
> >
> > All you know everything about the difference between procedural
> > programming and object oriented programming. And no matter, it is most
> > useful the second one. Then, why we draw in procedural mode instead of
> > oo mode?
> >
> > Geometric entities in a draw are the same as the lines in a printed
> > program. Even less complex ones. In fact if I change the order in a
> > printed code line in a program the program won’t even start, instead if
> > I change the order of the entities in a draw nothing wrong happens. The
> > entities in a drow are free from semantics and structure!
> >
> > All of us think about 3D drawings as special ones because of are visual
> > and recognizable. But 3D drawing is special because the designer build
> > and handle objects, and the computer software manage them easily.
> >
> > If you want to do it in 3D you don’t need to do it. You can build,
> > handle and manage objects even in 2D environment. The geometric entities
> > are 1D objects in a 2D environment.
> >
> > The objects we can handle are 2D surfaces in a 2D environment. The
> > surface is the result of a 1D entity closed frame. I mean “frame” as a
> > chain of entities: the end point of an entity is the starting point of
> > the next entity.
> >
> > In a surface you can describe an inside or an outside, a filled side or
> > an empty side. And you can have a function applied to the surface. You
> > can have a hole on a surface. Even you can hide a surface on others and
> > sketch the shadow on it. You can link two surfaces, intersect, add or
> > subtract each others.
> >
> > The final result of all these functions is the projection (view) of the
> > physical object, and you can relate it with other projection of the same
> > object.
> >
> > The projections are positioned on the sheet and dimensioned. You can’t
> > handle 1D entities outside a surface because if you do it you would
> > create a non sense. The designer just have to mind about draw surfaces
> > instead of draw random entities.
> >
> > You can do even more
> >
> > Each function own the tree of functions who generate it. You can
> > generate a function and figure again it’s projection. You can even
> > change the input surfaces of the functions and figure again it’s
> > projections. The surfaces  patterns may be parametric, I change one
> > parameter and figure again the relative projection.
> >
> > One projection may be set in relation to the others. In this way if you
> > move or change the projection even the son projections move or changes.
> >
> > It’s a new world!
> >
> > Why do we go on as usual and manage a simple list of entities?
> >
> >
> >
> > Best regards..
> >
> > Paolo Zambetti
> >
> >
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