Bug? Length Snapping not working on edges?

Hi Everyone… doing another another covid lockdown exercise and struck this unexpected snapping action…

I am studying an interesting apartment in San Paulo (Archidaily link = Gallery of Ubá Residential Building / Jacobsen Arquitetura - 27 )
and tracing a floor plan to build and approximate 3d model.
The floor plan is a jpg texture applied to the outline of the ground slab and using the rectangle tool to create walls and room spaces with my length grid set to a convenient 50mm.

Everything is going as planned but I noticed that if the free end of my rectangle is not near any entities it respects the length snapping but as soon as I want to link to an existing wall [edge] the snapping function is disabled …

Very frustrating as the process is so quick if snapping distance was retained -

maybe SU needs a grid snap rather than a length snap?

Just noticed I lose snapping also when I inference an existing edge

Screenshot 2021-08-27 102422

Am I missing a modifier key to force length snapping in all cases?

Of course there are workarounds but the current action is certainly not intuitive

I would say that the current consensus is: Forget about length snapping. It is more a nuisance than anything useful.

Turn off length sampling.
Are those points really aligned by axis? Your image may not be exactly straight. Turn on crosshairs in preferences to see alignments better.

Well I know that is the common wisdom regarding length snapping and I would prefer there was a user definable snapping grid available but apart from this frustration I don’t have any problem quickly getting incremental setout based on my snap distance using this process and my question still stands is this a bug in distance snapping when referencing an existing edge ???

Perhaps Colin can explain the technical reason for this seeming anomaly in distance snapping ?

everything is on axis, though that is not the issue, one of the advantages of using the rectangle tool

I think I understand better now… Sorry, no answer, since I cannot duplicate your results. Seems to work for me–and besides I use 2019 on Mac. Maybe it IS a NEW bug.

Thanks for the feedback… as it seems not a problem on the Mac maybe it is or maybe we have different SU workflows or settings… will investigate further…

I must learn how to create those nifty little gif videos :slight_smile:

OK , managed to figure out “ShareX” screen capture to share this clip that summarised the failure of length snapping when inference locks to an edge… Pressing the ALT key does not disable the inferencing when creating a rectangle…
length snap

No modifier key seems to disable the interference of inferencing edges when you prefere length snapping to work.

The only way I somehow seem to manage to get rid of dragging the inference along with the second corner (corner to be) is to model in parallel projection in top view. Try if that would work on your floor plan.

I DO see this using the rectangle tool. The length snapping drops out (in both directions) when contacting an edge. This is similar to other software, but in other software you can choose to turn off the object snapping.

Drawing only with edges, the length snapping is maintained. Only you can’t draw between two edges and have the edge tool ignore the object snap to get the even increments.

Moreover length snapping is not “grid” snapping, which is much more useful in rectilinear layouts. So in your example, showing the global locations, I don’t think that endpoints would be constrained at specific global increments, except with very careful input, which is only partly helped by length snapping.