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Comment by engr | Hacker News Reader

I have been working on a .net wrapper for opencascade (https://github.com/veggielane/EngrCAD) but opencascade interop from .net is a pain. I also fell in and out of love with SDF, as most CAM tools need BREP.

I agree with people in this thread, the world needs more CAD kernels. I also think that we need a language agnostic markup language to represent the BREP.

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Out of curiosity, why did you fall out of love with SDF?

Also curious why BREP is represented through a language rather than e.g. a tree or graph (or maybe this is just a language shortcut, and the idea is that the language is used to specify BREP objects?)

I want my data to be compatible with existing CAM tools so I can get parts machined.

I like BREP via language, it allows great flexibility and ability to query geometry at run time, e.g. Find all vertical edges to apply radius.

>> I also think that we need a language agnostic markup language to represent the BREP.

I agree with that, but some serious decisions have to be made or it will end up a mess like STEP.

Yeah, agreed. Would be cool to have multiple CAD kernels using the same markup language, then you can easily version control and use it for interchange.

In what way do you consider STEP to be a mess?

ISO 10303-21 is annoying to read and write, with an awful lot of stuff not used by CAD tools

Don't read or write it then, use software that will do it for you.

I don't know of anything that isn't useful in ISO 10303-21.

Couldn't one build a SDF-native CAM tool? That should be even a better fit than B-reps, no?

SDF for CAM would be a great approach, but quite a big beast to attempt

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