Work In Progress: Expose OCCT 7.2.0 about pythonocc-generator

[rainman110]

@tpaviot I think I know, why the downcasting is not working anymore.

Under the hood, swig manages all references to objects via their handles. When downcasting one object to another type, we were exploiting the inheritance chain of the handles. For example Handle(Geom_BSplineCurve) is inherited from Handle(Geom_Curve). Swig uses the inheritance type information to check, what handle types are allowed for the downcasting arguments.

In OCCT 7, handles are standalone classes that don't use inheritance. Still, Geom_BSplineCurve is inherited from Geom_Curve, but their handles aren't. This is the reason, why swig does not accept anything else for downcasting other than Handle_Standard_Transients!

We need to make swig aware of the underlying inheritance chain of the non-handle objects. I suppose, we ca use the typecheck typemaps of swig somehow.

[tpaviot]

@rainman110 No, it's this line:

typedef opencascade::handle <Standard_Transient> Handle_Standard_Transient;

If I remove it, everything goes right. It appeared after a change to generate_wrapper.py

I really have difficulties to work with SWIG warnings. They're not documented, not easy to know what to do to avoid them.

[trelau]

awesome work. moving forward do you intend to keep OCE up-to-date or are you planning on just using the OCCT releases?

[jf---]

A screenshot including an AIS_Manipulator

WOW! That's wonderful! So eager to delve into the generalized fused goodness!

[rainman110]

Wow... Great progress! Congratulations for this achievement.

@tpaviot I'll have a look at the handle wrapper and try to fix downcasting. I suppose, we just need some small adaptations.

[tpaviot]

@trelau I plan to keep OCE up to date

Thank you @rainman110 maybe you should read the migration guide that contains information about handles https://dev.opencascade.org/doc/overview/html/occt_dev_guides__upgrade.html#upgrade_700

[rainman110]

I think a narrowed down the problem and have a potential fix.

@tpaviot I cannot completely build you branch 7.x. There are still a couple of errors ( i am building on windows). So, can you already build it completely with your generated files?

[tpaviot]

@rainman110 I only tested on Linux so far, still did not try on Windows. Usually, Windows comes with its bunch of compilation errors, and I have to remove failing classes/methods from the Modules.py file. There are much less differences between Linux and osx

[rainman110]

@tpaviot I found one of the main culprits! In Standard.i you define

/* rttiext only ojects wrapped as handles */
%define Handle_Standard_Persistent Handle(Standard_Persistent)
%enddef
typedef Standard_Persistent Standard_Transient;
/* end rttiext only declaration */

This breaks the whole inheritance chain, such that Standard_Transient becomes defacto unknown for all deriving classes. This on the other hand breaks DownCasting.

I really suggest turning the swig warnings on for development since then it is much more clear, what is going on. With the default settings, all these valuable informations are hidden.

[rainman110]

@tpaviot Really? Everything works?

Then, windows is still an issue. Here we have the problem, that Handle(Something) is a different class than Handle_Something and swig won't convert between them right now. This is a visual c only thing and intended by the occt devs (see standard_handle.hxx). I am still looking into this.

[tpaviot]

ok I see, indeed Handle(Class) and Handle_* are different for msvc

[jf---]

I really have difficulties to work with SWIG warnings. They're not documented, not easy to know what to do to avoid them

Would it be straightfwd that the warnings bubble up depending on a environment variable?

[adam-urbanczyk]

@tpaviot great work! Can't wait to try it out.

[tpaviot]

@rainman110 I updated both the generator and the wrapper, in a simpler way. There's no need to modify the OccHandle.i script anymore, and Downcasting works as expected (on Linux)

[rainman110]

@tpaviot Great! Well done.

I'll see, what I can do for Windows. Unfortunately, It might take a while until I find the time.

[rainman110]

@tpaviot Can you please commit the changed code to pythonocc-core to branch wip/occt7x-support?

[tpaviot]

@rainman110 I already did it. I use to push -force to this branch. fetch your local copy and reset the wip/occtx-support to origin/wip/occt7x-support to have latest changes.

[rainman110]

@tpaviot Ah okay... did not see that!

[Trophime]

Any update on this?

[tpaviot]

Outdated. pythonocc-core now targets opencascade 7.4.0