Groups

[thornuk]

I've been teaching CAD for a few decades, but am new to QCad.
I'm looking for a means to group entities, but can't find anything. I need to construct a shape, for example a plan of a greenhouse being a rectangle with a mid span line in both vertical and horizontal directions. The only way I've been able to construct this is by drawing single lines and ensuring their start and finish co-ordinates match their appropriate other lines ( a bit like the cross of St George). (If I draw it as a rectangle, subsequently clicking on a line shows it to be a collection of four separate lines, so not a single entity - moving one leaves the others behind, destroying the required image).
Having drawn the shape I then need to move it around (eg: the drawing of the garden) to determine the best position of the (eg) greenhouse. I have drawn the "greenhouse" on its own layer, but that offers no solution to being able to move the collection of lines, and possibly rotate it.
As mentioned, I have experience of teaching 4 or 5 different CAD programs, including 3D parametric, but this is the only one I've used which seems not to have an explicit "group" facility.
How can I achieve this ?
Thanks

QCAD Version: 3.28.1.0 (3.28.1)
Windows 10 Home (all updates)

[andrew]

You would use blocks for this (blocks are essentially named, reusable groups). Part V in the QCAD e-book is about blocks and how to use them.

[CVH]

Hi,

https://www.qcad.org/rsforum/viewtopic. ... 310#p36310
Blocks typically group entities which are all part of the same object in the real world (e.g. a bolt, a plant, a machine part, etc.).
> Things of the same geometry.
Layers group entities with the same meaning in the real world (exterior walls, water pipes, center lines, invisible edges, etc.).
> Things that should display alike.

QCAD has no concept of groups nor of parametric relations.
https://www.qcad.org/rsforum/viewtopic. ... 361#p38361
https://www.qcad.org/rsforum/viewtopic.php?f=31&t=9405

Regards,
CVH

[Husky]

I've been teaching CAD for a few decades, but am new to QCad.

15 years ago I was in the same position like you now. First I tested the Community Edition but swiftly switched to QCAD Pro. I never regretted my decision to stick with QCAD despite my experience with much more expensive CAD packages.

I'm looking for a means to group entities, but can't find anything.

You have two option: Blocks (already mentioned by Andrew) or the temporary solution with a selection. A selection can be used to e.g. move or rotate etc. a temporary group of entities.

I have drawn the "greenhouse" on its own layer, but that offers no solution to being able to move the collection of lines, and possibly rotate it.

Select all entities on that layer with right click on that layer in the layer list / context menu and move / rotate those entities. If you have to do that on a daily base it would make sense to built a block for those entities.

The only way I've been able to construct this is by drawing single lines and ensuring their start and finish co-ordinates match their appropriate other lines ( a bit like the cross of St George). (If I draw it as a rectangle, subsequently clicking on a line shows it to be a collection of four separate lines, so not a single entity - moving one leaves the others behind, destroying the required image.

Common praxis would be to use the rectangle tools for this task. The rectangle tools are equipped with a polyline option (Option bar) - makes life perhaps easier. BTW - you could also convert a 4 line rectangle to a polyline ...

[thornuk]

Thanks for your swift reply.
However, I tried that, but subsequently selecting one of the lines of the rectangle shows it as individual, not linked to the other three lines, so moving it / rotating it will separate it from the others.
Plus that doesn't solve the issue of creating a shape with multiple lines which need to operate together, eg: (I tried to copy the shape I'm talking about, but I don't seem able to paste it here).
I have drawn it as a block on its own layer. I haven't found a way to move it / rotate it en masse.

[CVH]

However, I tried that, but subsequently selecting one of the lines of the rectangle shows it as individual, not linked to the other three lines, so moving it / rotating it will separate it from the others.

For a rectangle, the other Draw .. Shape polygons see Option Toolbar and tick the tool option 'Create Polyline'.
For any open or closed string of lines and arcs including approximations of a spline or ellipse see Polyline from Selection (OC).

Remark that most QCAD tools have their options listed on the common Options Toolbar.
Some things are stored as application preferences ... E.g. tolerance and gap bridging for OC

(I tried to copy the shape I'm talking about, but I don't seem able to paste it here)

One can not copy QCAD entities and paste them on the forum, no.
Attach a DXF snippet or a screenshot as per forum rules above.
https://www.qcad.org/rsforum/viewtopic.php?f=47&t=3760

I have drawn it as a block on its own layer. I haven't found a way to move it / rotate it en masse.

First make a selection then use one of the modifying tools, works for a collection of entities, a polyline, a block and so on.
With holding the Shift key one can add (subtract) entities to (from) the current selection.
Also have a look at the selection menu (another 9 methods, 5 of which have 4 modes).
To clear the current selection simply click on empty space.
A more specialized selection method is the Selection Filter, if not displayed type the shortcut key sequence 'GF'

Grouping options.dxf

(108.36 KiB) Downloaded 184 times

One can also drag a selection.
Make the selection and then click and hold near a reference marker but avoid to click on the marker.
Move your cursor a bit and then release the mouse button.
The selection will stick to your cursor with the nearest marker.
Indicate a new position for this marker.

Dragging the marker itself will alter the shape ... All of the selected related to the marker position.

Then there are the quick modifying tools: The keyboard arrows and F5/F6 with the Shift or Alt multiplier keys.
Again active on the current selection.

Tons of options to modify a selection as a whole.
At first, learning to use QCAD may seem rather different and difficult, but eventually you will find that it is very intuitive.

Regards,
CVH

[thornuk]

Many thanks for the replies, and the advice. I'm sure it will all sink in (eventually !).
I have to say I find it incomprehensible that a program as obviously powerful as QCad does not have a "group" function (by whatever name). If every compound shape has to be made into a block and set on its own layer, any useful drawing must has an astonishing number of layers. (Have I missed some overwhelmingly simple alternative solution ?)
I have found my way round some of the idiosyncracies.
I didn't realise that, when drawing a rectangle, using the rectangle & two diagonal points option, it starts with some kind of reference point, and THEN apparently allows one to drag out a rectangle from some other start point. (I have difficulty seeing the purpose of the reference point - why not just start the rectangle where you first click and drag it to its finish diagonal ?).
This is compounded when then altering the start co-ordinates (in order to move the rectangle to a new position); it already has been "told" it is a rectangle, so should internally know the co-ordinates of all the related nodes, but when I wish to move said rectangle it separates the line I select and divorces it from the rest of the shape. What's the advantage of doing this? I tried using a Polyline to draw the rectangle, and it only allowed me to change the co-ordinates of the start point, which it did in isolation to the rest of the shape, thus distorting it. No other nodes were shown in the Properties management panel.

[CVH]

I have to say I find it incomprehensible that a program as obviously powerful as QCad does not have a "group" function (by whatever name).

We already explained that at this price there are no parametric relationships, and QCAD does not support groups like ACAD.
The links to the topics are mentioned above.

If every compound shape has to be made into a block and set on its own layer, any useful drawing must has an astonishing number of layers. (Have I missed some overwhelmingly simple alternative solution ?)

I think this is based on a conceptual misinterpretation.
Blocks are intended to group things that belong to the same geometry, like: a bolt, a table, a machine sub-part, ...
With all the details associated with it: outlines, hidden lines, center lines, text, dimensions, ...
Layers are intended to group things that should look alike, printed alike.
For example thick & black or fine & dashed & red or normal & center line & orange ...
Also meaning that a block can consist of entities on different layers to control their attributes.
The block reference entity (the visual copy) also lives on a layer like any other drawing entity.
There is no reason to create a block for every single 'shape' nor an individual layer for that matter.

I didn't realise that, when drawing a rectangle, using the rectangle & two diagonal points option, it starts with some kind of reference point, and THEN apparently allows one to drag out a rectangle from some other start point. (I have difficulty seeing the purpose of the reference point - why not just start the rectangle where you first click and drag it to its finish diagonal ?).

Draw .. Shape .. Rectangle (RE) draws a rectangle from two user indicated positions.
One corner will be at the first indicated point, the opposite corner at the second indicated point.
There is little more to it. No surprises there.

All depends a bit on your snapping options, Auto snap (SA) should be fine.
I hope that you don't refer to RE and then SN because that would require 3 positions.

For the 'some kind of reference point' I think that you refer to the little red crossed circle, the relative zero position.
This is only used for entering coordinates relative to the last used position (in this QCAD session).
Like 10 left and 12 up (relative) or 100 units in a certain direction (relative polar).
You may notice that the relative position follows your actions.
And this whatever coordinate method is used to define a position (absolute, absolute polar, relative or relative polar).

This is compounded when then altering the start co-ordinates (in order to move the rectangle to a new position);

I already explained how to move a selection as a whole:

Make the selection and then click and hold near a reference marker but avoid to click on the marker.
Move your cursor a bit and then release the mouse button.
The selection will stick to your cursor with the nearest marker.
Indicate a new position for this marker.

This works just the same for any multi selection of entities: lines, shapes, arcs, text, ... block, pictures, hatches, ...

it already has been "told" it is a rectangle, so should internally know the co-ordinates of all the related nodes, but when I wish to move said rectangle it separates the line I select and divorces it from the rest of the shape.

There is no concept of 'shapes' or enclosed areas as we humans see it, all is merely line-art.
The number of possible named and unnamed 'shapes' we can construct with 3-4-5-... line pieces is about endless.
A rectangle is in fact a 4-sided polygon, a square is a special case of a rectangle, ...
Without parametrics: "right-angled", "parallel", "regular/irregular", and so on has no meaning.

You probably instructed QCAD to draw a rectangle shape as 4 loose line segments.
Every of the 4 entities now lives unrelated side by side.
If you opted to create it as a polyline then it will be a string of line segments, the relation is that endpoints are connected.

When a 'shape' of loose line segments is isolated from the rest it may be an option to double click near one of the sides.
Double clicking will select the nearest entity and all that are connected by endpoints.

What's the advantage of doing this?

Freedom for the designer, not every user will draw a rectangle as a fixed 'shape', it can be the intention to modify it or use it for another purpose.

I tried using a Polyline to draw the rectangle, and it only allowed me to change the co-ordinates of the start point, which it did in isolation to the rest of the shape, thus distorting it.

You probably dragged one of the reference points by its marker.
This method is intended to alter (distort) the polyline layout and works just the same with selected loose entities endpoints.
To pick up whole the 'shape' you need to click and hold on the 'shape' but near a reference marker as explained above.
Move a bit, once the selection sticks to your cursor you can release the mouse button and indicate a new position ...
... As one piece, as whole the selection

No other nodes were shown in the Properties management panel.

All vertices of a polyline are listed in the Property Editor.
A node is a point, a vertex is a node with a few more specific properties: bulging, widths.
If you select the shape then the vertex with index 0 will be shown, the starting point.
Just a matter of selecting the required index (0-3 for a polyline with a rectangular shape).
You may notice that the related node is indicated shortly in the drawing panel.

Regards,
CVH

[thornuk]

CVH - many thanks for that extensive explanation - I'll work through it in detail later, but right now I really appreciate your taking the time to respond, and the advice you've given - most helpful = many thanks, I'm sure it will be helpful.