Datum Plane orientation request

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Jee-Bee
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Re: Datum Plane orientation request

Postby Jee-Bee » Fri Aug 30, 2019 2:10 pm

Jee-Bee wrote:
Fri Aug 30, 2019 11:48 am
I agree on this topic with saso. A plane have an orientation and NO origin. During sketching i agree (Partly) with chris to show a (the) transposed (Part/ Body) Origin on the sketchplane (whatcould be a datum plane) but don't show anything regarding of orientation outside the sketch.
DeepSOIC wrote:
Fri Aug 30, 2019 1:35 pm
That is, change the default attachment mode of PartDesign Sketches to a new mode, that always projects the body origin to become sketch origin, and always reconstructs h/v axes directions, instead of inheriting those from the plane. I think that's a rather good way to go, too.
Thanks you descibe it better as what i did!!
chrisb
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Re: Datum Plane orientation request

Postby chrisb » Fri Aug 30, 2019 3:12 pm

Trying to get back to normal.
saso wrote:
Fri Aug 30, 2019 12:00 pm
as for distinguishing the planes from your example... what exactly do you mean?
I meant it in the sense asked for in the first post, or by RatonLaveur, ...
RatonLaveur wrote:
Tue Aug 20, 2019 3:31 pm
I never know which direction they are oriented until my sketch is mapped drawn and extruded.
... which is basically "what will happen if I use this DatumPlane". And, of course, I want to know before doing anything else because it would be double work - which we may agree is not desired - if it has to be changed.

If I map a sketch containing a circle to each of the planes shown above and pad them I get:
Snip macro screenshot-887199.png
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Snip macro screenshot-6bd92c.png
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Snip macro screenshot-79f0f0.png
Snip macro screenshot-79f0f0.png (6.16 KiB) Viewed 347 times
Which are clearly different. It would have been easy to anticipate if the DatumPlane had shown locally something like the global View->Axis cross:
Snip macro screenshot-3d3008.png
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Snip macro screenshot-440b21.png
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Snip macro screenshot-222fee.png
Snip macro screenshot-222fee.png (2.49 KiB) Viewed 347 times
DeepSOIC wrote:
Fri Aug 30, 2019 1:35 pm
An alternative way of tackling the problem is to get rid of every case where plane origin is used. That is, change the default attachment mode of PartDesign Sketches to a new mode, that always projects the body origin to become sketch origin, and always reconstructs h/v axes directions, instead of inheriting those from the plane. I think that's a rather good way to go, too.
That's closer to the common mathematical definition of a plane. However, looking at the models I have seen here and my own, in most cases the center of the DatumPlane (i.e. (0,0,0) of its placement) has a special meaning in the attached sketch. So it would mean double work to attach the plane and afterwards to get that point again. In some cases it would be extremely difficult, e.g. with inertia AttachmentModes. So I would prefer DeepSOIC's first proposal as shown in the last three images here.
Jee-Bee
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Re: Datum Plane orientation request

Postby Jee-Bee » Fri Aug 30, 2019 4:38 pm

I don't think we must want to add a LCS on the plane! In my opinion it is already weird that i am possible to translate a plane parallel (not in hight) :shock: .
I agree that there should be a method to distinguish the Positive and Negative side of the plane...
I can imagine:
- different color front and back
- Filled plane or single line
- ...
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DeepSOIC
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Re: Datum Plane orientation request

Postby DeepSOIC » Fri Aug 30, 2019 4:52 pm

So, for a potential developer (me, possibly), here's a list of things to do.
* add CS marker to datum planes, at least for the time it is being attached.
(that way, it will be easier to understand what roll,pitch and yaw do)
* (if possible) make datum plane's top and bottom look different.
* new attachment mode for sketches, to treat a plane as a plane.
* make the new attachment mode default for sketches made on datum planes.
* an option in preferences to change it back, for those who can't adapt to use LCS instead of a datum plane.
* make it easy to attach sketches to LCS object in PartDesign.
Does that sound good?
RatonLaveur
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Re: Datum Plane orientation request

Postby RatonLaveur » Fri Aug 30, 2019 5:35 pm

You're a machine. Except for #5 (where I really would adapt happily but again, I'm aware me is me and FreeCAD is we) all these points have strong impact in my book. Even a single one of them would already be great.
Jee-Bee
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Re: Datum Plane orientation request

Postby Jee-Bee » Fri Aug 30, 2019 5:36 pm

As result of this topic i am playing a bit around with with all datum types... Till now it annoys me more than i wanted :(
  • A orgin have no LCS(should be easy but...)
  • selecting a line/ axis as reference for a datum plane can ONLY normal to this reference I expect also trough
  • Creating a point on center of all 3 planes I get a infinite shape profided error.
  • why can a point rotate it don't have a shape
  • When attaching a plane to 3 points and i add a pitch around what point it is rotating...
that it so far

I would almost request te rethink all datum stuff
RatonLaveur
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Re: Datum Plane orientation request

Postby RatonLaveur » Fri Aug 30, 2019 5:56 pm

...yup....i tried to keep the scope of the discussion limited ;) let's be fair we ain't far from something awesome.
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Zolko
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Re: Datum Plane orientation request

Postby Zolko » Fri Aug 30, 2019 6:11 pm

DeepSOIC wrote:
Fri Aug 30, 2019 4:52 pm
* make it easy to attach sketches to LCS object in PartDesign.
This one yes, definitively yes. The others I don't really understand.
try the Assembly4 workbench for FreCAD v0.19
installable with Tools > Addon Manager, new version 0.7. Simple tutorial here
chrisb
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Re: Datum Plane orientation request

Postby chrisb » Fri Aug 30, 2019 9:43 pm

DeepSOIC wrote:
Fri Aug 30, 2019 4:52 pm
Does that sound good?
Yes. Depending on the number of users who want to use 3 and 4, these points and 5 it could be delayed and handled separately.
C_h_o_p_i_n
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Re: Datum Plane orientation request

Postby C_h_o_p_i_n » Sat Aug 31, 2019 11:44 am

Hey,

while I'm fairly new to freecad (playing / learning for about 4 Month) I was reading extensively to get a clue why and how thing are functioning.

In my understanding Datum objekts are (primarily/only) used to glue new sketches to a defined place in "space" - so Datum objects provide a reference/orientation anyway.

Taking this into account, I'm somewhat wondering why a datum Plane can not / should not act/behave as an (L)CS ?

... just to throw some thougts in ...

regards,
Stefan