Notes about Coordinate systems

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chrisb
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Re: Notes about Coordinate systems

Post by chrisb »

manos wrote: Sat Jul 02, 2022 10:22 pm Part WB and Draft WB are considered obsolete any more.
Is this just your personal opinion? To not start such discussion, say what you want to say explicitely, e.g. that for PartDesign users the global coordinate system is used only for placing the bodies.
The phrase should be "We can view the (Local) Coordinate system of the Body: Tree view ->Body->Origin and hitting Space."
As it is a bit more complicated just say "We can view the (Local) Coordinate system of the Body by making Body->Origin visible"
The phrase should be "Sketches have their own Coordinate system too" . We can see it when editing the Sketch.
I don't think that there is a possibility to see the coordinate system of a sketch.
The phrase should be "Objects with shape have their own Coordinate System"
Not true, all PartDesign features have a shape but no coordinate system.
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manos
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Re: Notes about Coordinate systems

Post by manos »

chrisb wrote: Sat Jul 02, 2022 11:38 pm
manos wrote: Sat Jul 02, 2022 10:22 pm
The phrase should be "Sketches have their own Coordinate system too" . We can see it when editing the Sketch.
I don't think that there is a possibility to see the coordinate system of a sketch.
When we edit the Sketch at Sketcher WB or at PartDesign we see the X and Y axis (and Z is vertical to them). Aren't they the 3 axis of the Sketch ?
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Re: Notes about Coordinate systems

Post by chrisb »

I forgot: Although I can handle various document formats, I think here a simple ASCII-format would be best. It is directly visible here in the forum, it can bear all information needed, and it can be handled by everyone on every system.
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manos
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Re: Notes about Coordinate systems

Post by manos »

adrianinsaval wrote: Sat Jul 02, 2022 8:12 pm
mfro wrote: Sat Jul 02, 2022 3:54 pm In FreeCAD, this is exactly the same: the "Position"-attribute tells everybody where your property (= Body) is located in global coordinates (just like your phone does navigating you home).
Not at all, an object's placement property is always relative to it's parent coordinate system, all of this is very complex and as chrisb says it's really necessary to talk about placement and attachment to truly understand these subjects.
.....
@adrianinsaval,mfro Your informations pertain to every case of Attachment and Placement usage or just for one WB e.g. Part Design WB?
In general Properties of Attachment and Placement objects are the same in all cases ?
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Re: Notes about Coordinate systems

Post by manos »

adrianinsaval wrote: Sat Jul 02, 2022 8:12 pm
As for the document format, I just find it annoying having to download a file and open a full blown office text processor just to read/edit some plain text. That's why I pasted the text directly in the forum.
Your opinion is reasonable adrianinsaval.
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Re: Notes about Coordinate systems

Post by manos »

adrianinsaval wrote: Fri Jul 01, 2022 5:46 pm Also you haven't adressed any of this:
sketches and any object with a shape do have an internal axis system, but they aren't visible, this is only relevant when editing their attachment. What's important to understand is that you can have many levels of nested coordinate system, for example you can have a sketch attached to a LCS inside a body inside a Part inside a Part, that's 6 levels of nested CS if we count the global CS, each is defined relative to it's parent through their placement + attachment offset (when it exists).
I agree with them.
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onekk
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Re: Notes about Coordinate systems

Post by onekk »

manos wrote: Sat Jul 02, 2022 10:22 pm Part WB and Draft WB are considered obsolete any more.
With this sentence you will show that you don't know the very basic truth about FC.

FC is build upon two "main" pieces of code:

1) OCCT or the "modelling engine", that is the "core" orf FC
2) Coin3D (Pivy) that is the "visualization engine" of FC

Part WB is the "coupling" between FC and OCCT, saying that is obsolete in this case is not only "not correct" but an insanity.

Draft WB is supplying most of the "tools" used when dealing with 2D geometries as example in Arch WB (one of the other "pillars" of FC).

Part Design WB is somewhat seen as the "modern way" to model with FC. but is built upon "Part WB" as it use OCCT, adding some complexity and abstraction over the simple "modelling engine" calls, it contains some "high level" operations that could be used to simplify some work with FC.

But with each level of complexity you add also some "restrictions" and other things, that could complicate things.

Plus most of the WB do something similar to this:

Code: Select all

import FreeCAD
import FreeCADGui

import Part

from Draft import <something>

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Carlo D.
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Re: Notes about Coordinate systems

Post by manos »

chrisb wrote: Sat Jul 02, 2022 11:38 pm
manos wrote: Sat Jul 02, 2022 10:22 pm Part WB and Draft WB are considered obsolete any more.
Is this just your personal opinion?
No it is not . It is just the outcome of mess up of terms, misjudgement of data, facts and text.
Mea culpa.
Last edited by manos on Sun Jul 03, 2022 4:01 pm, edited 1 time in total.
manos
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Re: Notes about Coordinate systems

Post by manos »

onekk wrote: Sun Jul 03, 2022 10:12 am
manos wrote: Sat Jul 02, 2022 10:22 pm Part WB and Draft WB are considered obsolete any more.
With this sentence you will show that you don't know the very basic truth about FC.

Carlo D.
Or simply that a mess up of terms has occured followed by misjudgement of data, facts and text.
Mea culpa.
manos
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Re: Notes about Coordinate systems

Post by manos »

chrisb wrote: Sat Jul 02, 2022 11:59 pm I forgot: Although I can handle various document formats, I think here a simple ASCII-format would be best. It is directly visible here in the forum, it can bear all information needed, and it can be handled by everyone on every system.
OK, OK Text file from now on .
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