How is a line a curve?
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Hi,
I use TIG's Extrude Tools extensively and when i need to create meshes with straight rails i use the , then divide this, and finally use Rick's Weld plugin.
This works fine for me everytime but i don't know why a segmented line is a curve? As i do it anytime i need to make meshes it seems i should at least know why?
Can someone point me in a direction to find out? Or am i doing something wrong already?
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There are only really two types of basic geometry in SketchUp.
A 'Face' and what bounds it - an 'Edge'.
An 'Edge' doesn't need a 'Face', but a 'Face' needs 'Edges' [at least 3 in a loop]
Edges can be 'associated' together to form 'Curves', but a 'Curve' is just a collection of 'Edges' - so they'll Select all together etc. It might have been better, to call them 'PolyLines' but when SketchUp started off someone chose the name 'Curve'...
These 'Curves' can exist in 2D or 3D - clearly only 2D 'coplanar' ones could have a Face.
There are also special sub-types of 2D 'Curves' - called 'Arcs' which have regular 'Edge' size [called 'Segments'], a radius, a center etc but these are open ended, and when they loop so that they have no ends they are called 'Circles' [or 'Polygons' which are similar to 'Circles' but these don't make smoothed forms when extruded in 3D].
Note how 'Faces' can also get associated together - into 'Surfaces' - the differences here become noticeable with hidden geometry on/off...EEby.. Tools:
So that users can easily select a collection of 'edges' as the path for making meshes etc I decided that I'd limit it to them selecting a few curves [some tools like EEbyEdges let you use plain edges etc inside two selected groups - but this was a way to allow discontinuous edge selection and the group replaces the curve as the 'container' of these edges...]. By picking just curves the tools can tell when the next curve is coming etc...
A curve is any collection of continuously joined edges in a single 'string' - RickW's Weld tool allows you to pick edges or other curves and 'weld' them into one new 'curve' - even in 3D [native curves from basic SUp are all 2D]. Also the Bezier tool makes special collections of edges connected in curves that happen to have special mathematical properties and forms.
If you want a straight connection as a rail then using the new EEbyLoft with just the 1 section specified will suffice. However, if you want a straight rail but with several 'segments' to it, so that the mesh is more subdivided, then use Divide on one piece of Edge and immediately Weld it to a 'straight' Curve...Hope this helps...
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I understand now why you have named your plugs Extrude "Edges" xxxxx
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@unknownuser said:
What do you want that will be?
Sometimes Frenchy you crack me up and make say 'Huh?' at the same time???
@tig said:
EEby.. Tools:
If you want a straight connection as a rail then using the new EEbyLoft with just the 1 section specified will suffice. However, if you want a straight rail but with several 'segments' to it, so that the mesh is more subdivided, then use Divide on one piece of Edge and immediately Weld it to a 'straight' Curve...
TIG,
your response explained and enlightened alot
But the above quote made me think about it along time before i had a 'D'oh' moment ( i think
)
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EEbyLoft [and some other EEby.. tools] takes the most divided curve [i.e. with most edges] as it's base for redividing other curves to match.
When you added more subdivisions to the central curve's 'straight' part it then has 2 extra edges, so the final mesh reflected that...
Get 'Entity Info' on each of the Curves in each version and you'll see the maximum edges count is more in one than the other [13 vs 15] - you can see the extra splitting of some edges in the first arced shape to even up the vertices... -
I never noticed that effect before and leads me to this....
So how does your plugin decide where these extra faces need to go?
Or as a user should it be a case of monitoring more closely your geometry before running the plugin?
My last query...
Is it possible to merge EEbyL with EEbyR, so i could select numerous profiles then 2 rails?
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It uses my own algorithm - it works out the maximum number of edges in the curves and then looks at each selected curve in turn, if its number of edges is different it works out by how many and then how many times the edges need subdividing to match the maximum, it also works out if not all of the edges need subdividing and apportions the division as evenly as possible across the segments.
In the case you showed 12 and 15 have 3 as a common denominator so you get three of the 12-segment curves' edges divided in half - which ones are determined by rules so they are as evenly spaced as possible...
In that case it can't be 'central'...
That's why it's suggested you use equal segmentation or at least simple multiples - that way the divisions are evenly spaced - large prime numbers for curves' segmentation work but can cause unevenness ! e.g. 7 & 13 - whereas 7 & 14 work fine...
I have no plans to merge these two tools - my brain aches already... 
Try doing sets of rails/profiles with EEbyRails in turn - you have to do a little work here ! -
Thanks for all the info TIG, my approach to your Toolset has now changed completely.
Keep up the great work
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