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by idleproc
1511 days ago
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I used CAD software back in the late 90's called Spirit. The floating point calcs were infuriating. You could draw a bunch of lines with exact length and offset them by exact distances and trim them and they'd all end up x.01mm etc. when you measured or dimmed them. Hah, people used to say. We've always used drawing boards, that kind of accuarcy isn't important. But I'd argue that it was. For my own sanity. Sadly, a standard UK brick is 215 x 102.5 x 65mm. Are bricks manufactured to a tolerance of 0.5mm? Can a builder measure to 0.5mm? No. But when you're digital, and you have a large building, small errors start to accumulate. Next thing is you have the builder on the phone saying the overall length of your building on opposite sides don't match, which one is correct? |
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Thankfully it seems that at least with 2D drawings and AutoCAD the worst side effect these days is that under certain circumstances hardware acceleration causes curves/curve segments to be displayed slightly offset. Strangely (but also luckily) enough it never happens when using just AutoCAD, but only when our road/railway design add-in is active (which displays all its output inside the AutoCAD drawing itself) [1], and it doesn't affect points picked via object snapping, i.e. it's really only the display that's affected.
Our friends in structural engineering or architecture on the other hand do indeed use local coordinate systems for their 3D models, though I can't say whether that practice is absolutely universal
[1] Edit: And also in the layout view, but thankfully definitively not in regular model space, where you'd be actually editing things.