Sketcher tutorial

A place to share learning material: written tutorials, videos, etc.
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Aug 12, 2018 9:47 pm

bejant wrote:
Sat Aug 11, 2018 5:16 am
chrisb wrote:
Fri Aug 10, 2018 9:00 am
Not finished yet, now it will have to wait another week.
No worries (IDWID, as we say) but for feedback I'll argue that you don't need to complete it before allowing others to review your work. I see that it is massive and I'd like to have a look (via upload or PM) and I understand that the document is still evolving.
I have to create the pdf at home as I had troubles with my first uploaded version. Currently I'm on a houseboat on vacations for a week with poor internet access. Well, among others, that was on purpose.
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
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NormandC
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Re: Sketcher tutorial

Postby NormandC » Sun Aug 12, 2018 9:55 pm

bejant wrote:
Sat Aug 11, 2018 5:16 am
IDWID, as we say
Thanks. The world really needed yet another obscure acronym :D (for anyone who's wondering: it's done when it's done ;) )

chrisb wrote:
Sun Aug 12, 2018 9:47 pm
Currently I'm on a houseboat on vacations for a week
Oh, nice. Enjoy it!
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Aug 12, 2018 10:01 pm

NormandC wrote:
Sun Aug 12, 2018 9:55 pm
Oh, nice. Enjoy it!
Thanks, I do!
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
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easyw-fc
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Re: Sketcher tutorial

Postby easyw-fc » Mon Aug 13, 2018 6:46 pm

+1 from me! Enjoy :D
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bejant
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Re: Sketcher tutorial

Postby bejant » Tue Aug 14, 2018 2:17 pm

chrisb wrote:
Sun Aug 12, 2018 9:47 pm
Currently I'm on a houseboat on vacations for a week
No hurry; enjoy your vacation!

NormandC wrote:
Sun Aug 12, 2018 9:55 pm
Thanks. The world really needed yet another obscure acronym :D
What? It's not so obscure around here :lol:
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sat Aug 18, 2018 9:32 pm

Thanks for all the good wishes, they have helped: Fantastic weather, family still united :lol: ...

Now I'm back to the playground and have a new version of my work about Sketcher. I have replaced the file in the first post. I had to compress it to get below the size limit. Please tell me if you prefer to have it on an external service instead.

sketcher.pdf.7z
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Aug 19, 2018 8:06 am

I was glad that I had finally finished the constraints part (so far), that I forgot some questions I would like to see considered:
  • When talking about perpendicular or tangent constraints I use all of a sudden new notions: what is usually called a line now becomes a line segment and a line is something of infinite length. I guess the experts can understand what I mean, but I'm not sure if I express myself clear enough to newbies. In german we have a different word for an infinite straight line ("Gerade"), is there an english equivalent?
  • for perpendicular and tangent constraint: I started with the lowest number of DOF consumed. Should I reverse the order and start with the point/point variants as they are more frequently used?
  • Since I hardly use it I'm looking for usecases with block constraints.
  • I am thinking about restructruring the document. The section "Constraints" would be divided in two subsections: "Geometric Constraints" with coincidence...block and "Dimensional Constraints" with horizontal distance...angle as subsections. What do you think? It would create an imbalance between the Geometric Elements part and the Constraints. Perhaps I should restructure the Elements as well with "Basic Elements" line, arc circle, point,... and "Compound Elements" polyline, rectangle, polygon, slot. Opinions?
  • Does it need an example for the lock constraint? It can be viewed as speedup of creating horizontal and vertical constraints.
  • I'm still looking for a very simple explanation why the length constraint consumes 1 DOF
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.
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bejant
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Re: Sketcher tutorial

Postby bejant » Sun Aug 19, 2018 11:45 am

chrisb wrote:
Sun Aug 19, 2018 8:06 am
In german we have a different word for an infinite straight line ("Gerade"), is there an english equivalent?
In geometry a Line extends infinitely in either direction; if there is one endpoint it is a Ray, if there are two endpoints it is a Line Segment.

Outside the context of of geometry (and outside mathematics in general) people usually simply say "line" when they are actually referring to a "line segment". As an example: "I drew some lines on the blackboard". People might say they drew "curved lines" (which in the context of geometry don't exist) but we usually understand that they are referring to arcs.

chrisb wrote:
Sun Aug 19, 2018 8:06 am
Since I hardly use it I'm looking for usecases with block constraints.
I thought it was for Constraining B-Splines. After adjusting the curve to your liking by dragging the control points by eye, the control points could be set by using the Block Constraint.

chrisb wrote:
Sun Aug 19, 2018 8:06 am
I'm still looking for a very simple explanation why the length constraint consumes 1 DOF
Maybe picture length as a Radius?
20180819b.png
20180819b.png (19.39 KiB) Viewed 996 times

20180819a.png
20180819a.png (20.56 KiB) Viewed 996 times

20180819c.png
20180819c.png (21.33 KiB) Viewed 996 times

Thanks for the update; I'll have to read through it before I post back here.
GeneFC
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Re: Sketcher tutorial

Postby GeneFC » Sun Aug 19, 2018 2:06 pm

chrisb wrote:
Sun Aug 19, 2018 8:06 am
I'm still looking for a very simple explanation why the length constraint consumes 1 DOF
Think of a simple line segment with two independent endpoint locations. We usually think in terms of cartesian coordinates, so each endpoint has an x-coordinate and a y-coordinate. Total of 4 DOF.

Now switch your thinking to polar coordinates. The line segment coordinates are (x,y) for one endpoint and (distance, angle) for the other endpoint. Still 4 DOF. Fix the distance with a constraint and there are now 3 DOF.

QED.

This may be too complex for your tutorial, but it may lead you to a create a simpler explanation.

Gene
chrisb
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Re: Sketcher tutorial

Postby chrisb » Sun Aug 19, 2018 2:10 pm

Thanks Gene and Bejant. I will create my explanation for 1-DOF-Length around the line example. I have done so with horizontal and vertical distance and I hope it will be understandable.
A Sketcher Lecture with in-depth information is available in English, auf deutsch, en français, en español.