How do you detect a Polygon?

TIG

@thomthom said:

@jim said:

Can't just check if 2 adjacent edges are soft? Circles are, polys are not, right?

Guess not.

You'd think so, so did I and TIG, but that's not the case.

Thinking of it - it makes sense that they don't as that would render extruded circles invisible.

Smooth/soft edges that are profiles stay visible...

Jim

Right, it's the connecting edges of an extrusion that are softened, not the perimeter of the polygon/circle.

thomthom

Only the edges that forms the outline of the geometry from the current view.

Look at it from an angle where it doesn't take part of the outline and it's hidden.

TIG

When you Smooth/Soften the Polygon's Edge its Face merges with the already Smoothed/Softened side Faces in the extrusion to give a single 'Surface' - as reported in the Entity Info Box. This 'Surface' Selects and Highlights as one thing... unless Hidden Geometry is 'on', then the separate Faces that make up that 'Surface' are individually Selectable/Highlighted. Presumably the [assumed] Face::is_surface? method that Entity Info uses, simply looks to see if some of the Face's Edges are Smooth/Soft and have extra Faces attached ?

thomthom

I added a feature request on this topic.

snicolo

Ok,
a quick and dirty way is to use

Sketchup.active_model.selection.count

if it returns 24 (default segments' number in a circle) it is a circle

if it returns anything else it is a polygon

This way does not work if you have 24 segments polygons or if you have changed the circle default segments number.

I am still trying to figure out a better way.

thomthom

Circles can be converted to Polygons - so that won't do either. Detecting circle is easy - checking the start and end angle if it's 360degrees or more. (SU weirdness - circles some times comes out with an total angle of 720 degrees...)

Personally I often change the default segment count. And I also get lots of circles from DWGs.

TIG

My new method ArcCurve.is_loop? tells you if it's an open ended Arc, or looped as a Polygon or Circle, ==no_loose_ends.
The other methods ArcCurve.is_circle? and ArcCurve.is_polygon? return true if it is...
A clunky fix but it works...

thomthom

FYI: the Google response to this:

@unknownuser said:

Hi Thomas,

I’ve traced this through the code, and I’m sad to report that there is nothing exposed in the API that allows you to (quickly) tell the difference between circles and polys. Internally, we store a flag so that says which tool created the curve object. I’ve logged a feature request to expose this in the API.

Until then, the only thing I can suggest is to make a hidden copy of the curve, extrude it, then see if the edges of the resulting faces are smooth. I haven’t tried this yet to see if it works successfully though.

Matt

thomthom

FYI: since SU 7.1M1 you can detect polygons using Curve.is_polygon?

TIG: that code snippet of yours will now conflict with the new API method.

TIG

@thomthom said:

FYI: since SU 7.1M1 you can detect polygons using Curve.is_polygon?

TIG: that code snippet of yours will now conflict with the new API method.

I know BUT not pre v7.1M1... using needing to detect a Polygon need both - with aversion test to load ?

thomthom

I use this: Sketchup::Curve.method_defined?(:is_polygon?)

But this is why I prefer not to extend the native classes. If someone has implemented the old code - it will still conflict unless that code is updated.

Instead I make methods where I also send the object I want to test. def MyLib.is_polygon?(curve) Completely future-safe.

TIG

Here's my three methods
(I've improved .is_loop? to trap any of the arc's vertices that have other edges that are not forming part of that arc !)...

ArcCurve.is_loop? returns true=Circle or Polygon: false=Arc
ArcCurve.is_circle? returns true=Circle: false=Arc or Polygon
ArcCurve.is_polygon? returns true=Polygon: false=Arc or Circle*** THIS Method is built-in from SUp v7.1M1

v1.2 has test to see if v7.1M1 built-in method if not makes is_polygon?
Other methods also trapped so as not to overwrite built-in methods...***

Usage: if not edge.curve.is_loop? then... ### it's an Arc...

They work, but are a clunky temporary fix...***

ArcCurveTests.rb

TIG

Updated all of the tests so only load is not built in methods... http://forums.sketchucation.com/viewtopic.php?p=188743#p188743