Freeze/Thaw vs. Hide/Show

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Jeffrey
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Joined: Wed Mar 22, 2023 10:57 pm
Location: Rayville, Missouri

Freeze/Thaw vs. Hide/Show

Post by Jeffrey » Thu Apr 06, 2023 7:43 pm

As a newbie struggling to set up some new drawings I discovered a feature I don't understand as to when/where/why it is used. I've got 50 years experience with old-fashioned pencil-paper drafting but I started using CAD and QCAD about 3 weeks ago.

In the Layer List I see we can "freeze" a layer as opposed to "hide" a layer. To make this easier to play with I set:
Application Preferences > Widgets > Layer List > Show frozen column

I froze some layers but could see no difference with hiding them. I was mystified and intrigued (a side track from getting the drawings done, but it is important to understand the program features).

I searched for understanding and found in the QCAD Reference Manual a note under Toggle Frozen Status:
"Note that block references on frozen layers are not shown while block references on layers that are off are still shown (provided that they contain any entities on layers which are on and not frozen)."

In playing with this in my drawing that has a number of layers and block references I continued to be mystified (I could see no difference between freezing or hiding). The QCAD Book says nothing about it. I searched the forum and found this:

https://qcad.org/rsforum/viewtopic.php?f=32&t=6123
User gntech: 'What is the difference between a "frozen" layer and a "hidden" layer? And when and how do I utilize the frozen layer functionality?'
Admin andrew: 'Block references on hidden layers are still shown, block references on frozen layers not (even if they contain entities on other, visible layers).'

Note that Andrew did not elaborate on the answer to the question of when/where/why it is used.

I did finally discover the obvious, that a layer that is frozen cannot be modified. But I'm still curious, is there a difference between freezing and hiding? If you hide a layer it can't be modified. If you freeze a layer it can't be modified. And what does all this have to do with block references, as mentioned in the reference manual and in Andrew's answer to user gntech?

Please, what is the when/where/why for the freeze/thaw feature? In other words, when is this frozen layer functionality important, where would you want to use it, why is the feature used ... who uses it for anything important and what is it intended to be used for?

If you are a long-time user of CAD/QCAD then there is probably an easy answer to this question. I would appreciate any practical application comments from those with experience using this feature.

Pro 3.28.1, Windows 7 32bit, Windows Installer
Attachments
W150 Meter Plate WP14+.dxf
Where I'm at after 3 weeks of learning QCAD
(116.43 KiB) Downloaded 151 times
Jeffrey Alan Klute - Data Vision Services
202 W Third ST, Rayville, MO 64084
"Necessity and Desire are the Mother and Father of Invention"

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Husky
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Re: Freeze/Thaw vs. Hide/Show

Post by Husky » Fri Apr 07, 2023 5:58 am

Hi Jeffrey,
Jeffrey wrote:
Thu Apr 06, 2023 7:43 pm
Please, what is the when/where/why for the freeze/thaw feature? In other words, when is this frozen layer functionality important, where would you want to use it, why is the feature used ... who uses it for anything important and what is it intended to be used for?
yes I admit it can be confusing until it isn't anymore. :wink:

I'll just share how I see it. I try to keep it simple but maybe it will help a bit ...
This said - what ever you decide to do is a personal preference - there is not really a right or wrong doing in using this features.

1, Basic info: Even that in both scenarios are no entities visible you are able to modify blocks on hidden layer but not on frozen layer

2. Marginal note: Frozen or Hidden layer can improve the performance of a drawing because frozen or hidden layer aren't render entities what can speed up the overall performance of the application.

3. Hiding a layer is more or less a in the moment action. E.g. you are active working on a current part of a drawing and need to get "things" (entities) out of the way for different reasons. I'm sure you will remember what is hidden - no great danger to mess something up. What could you mess up - blocks! It is correct that blocks are not anymore visible on a hidden layer but they are still "reachable" because of a still existing reference (blue dot) in the drawing to the block. Those references are snapable. A selection would show the blue reference point but only then.

3. Frozen layer are more designed for a kind of "I don't need to see them for a long time". If they are not visible for a long time you will "forget" what blocks are on it, how they are positioned etc. etc. and the danger to modify (move, scale, rotate etc.) or even delete a block accidentally is very high.

To understand it better try this.

Load my example drawing with blocks in QCAD.
Frozen vs hidden.dxf
(108.97 KiB) Downloaded 159 times
Husky_2023_04_06-01.png
Husky_2023_04_06-01.png (36.13 KiB) Viewed 1824 times

Freeze layer frozen,
hide layer hidden ... except the rectangle (layer 0) all blocks are now invisible, correct?

Husky_2023_04_06-02.png
Husky_2023_04_06-02.png (1.53 KiB) Viewed 1824 times

next ...
select all (TA or CTRL+A)

Husky_2023_04_06-03.png
Husky_2023_04_06-03.png (1.87 KiB) Viewed 1824 times

this selection will show the reference points. As you can see - there are only visible on the hidden layer. None on the frozen layer.

Use this selection to scale everything by 0.5. Keep in mind - our selection was "Select All"!

Now thaw the frozen layer and show the hidden layer.

Husky_2023_04_06-04.png
Husky_2023_04_06-04.png (29.15 KiB) Viewed 1824 times

Blocks on the hidden layer are modified - on the frozen layer not! :wink:
Hope this helps to understand better a "when/where/why it can be used.
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TSG
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Location: Germany

Re: Freeze/Thaw vs. Hide/Show

Post by TSG » Fri Apr 07, 2023 8:50 am

Good explanation but what‘s about „Lock“ ?

regards Thomas
Ich will nicht streiten. Ich will nur deutlich machen, dass ich Recht habe und DU NICHT.

Jeffrey
Newbie Member
Posts: 4
Joined: Wed Mar 22, 2023 10:57 pm
Location: Rayville, Missouri

Re: Freeze/Thaw vs. Hide/Show

Post by Jeffrey » Sun Apr 09, 2023 3:18 pm

Hi Husky!

Thanks very much for taking the time to elaborate on the differences and share the example file! Your reply has greatly improved my understanding of these features.
Husky wrote:
Fri Apr 07, 2023 5:58 am
yes I admit it can be confusing until it isn't anymore. :wink:

I'll just share how I see it. I try to keep it simple but maybe it will help a bit ...
This said - what ever you decide to do is a personal preference - there is not really a right or wrong doing in using this features.
I agree there's no right or wrong in practice. As I've said many times "you can't argue with success." However you arrive at something that works to get the job done it's OK (as long as it works).

Yes, it is confusing until some key definitions are understood. Part of my confusion came from the unmentioned distinctions in the meaning of what is meant in the QCAD Reference Manual under Toggle Frozen Status: When speaking of Hidden layers it says "block references ... are ... shown." Before your reply I could not see how this is true, because I wasn't looking at the block references by themselves, but at the drawing or visibility of the object the block represents. But the "light bulb came on" when you shared your example.

I'll share a further observation that requires this discussion include a consideration of what it means to Lock a layer.

A Frozen layer behaves the same as if it were both Hidden and Locked:

* Hiding a layer by itself does just that, i.e., the layer is not seen or printed. But block references can still be manipulated by Select All (TA or Ctl+A), i.e., the objects (that are not drawn or seen) can be manipulated, scaled, rotated or deleted (sometimes with unintended results).

* Locking a layer by itself does just that, i.e., the layer cannot be manipulated in any way BUT is seen and printed.

* Freezing a layer is the same as both Hiding and Locking the layer (not seen or printed and can't be manipulated in any way).

So in practical application, one use of the Freeze feature is to HIde and Lock a layer with one command or mouse-click.
Jeffrey Alan Klute - Data Vision Services
202 W Third ST, Rayville, MO 64084
"Necessity and Desire are the Mother and Father of Invention"

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