Std LinkMake/it: Difference between revisions

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{{Docnav
{{GuiCommand
|[[Std_Group|Std Group]]
|[[Std_LinkMakeRelative|Std LinkMakeRelative]]
|[[Std_Base|Std Base]]
|IconL=Std_Group.svg
|IconR=Std_LinkMakeRelative.svg
|IconC=Freecad.svg
}}

<div class="mw-translate-fuzzy">
{{GuiCommand/it
|Name=Std LinkMake
|Name=Std LinkMake
|Name/it=Crea link
|MenuLocation=None
|MenuLocation=None
|Workbenches=All
|Workbenches=Tutti
|Version=0.19
|Version=0.19
|SeeAlso=[[Std Part|Std Part]], [[Std Group|Std Group]], [[PartDesign Body|PartDesign Body]]
|SeeAlso=[[Std Part/it|Std Part]], [[Std Group/it|Std Group]], [[PartDesign Body/it|PartDesign Body]]
}}
}}
</div>


==Description==
==Descrizione==


{{Button|[[Image:Std LinkMake.svg|16px]] [[Std LinkMake/it|Crea link]]}} crea un [[App Link/it|App Link]] (classe {{incode|App::Link}}), che è un tipo di oggetto che fa riferimento o collega ad un altro oggetto, nello stesso documento o in un altro documento. È appositamente progettato per duplicare in modo efficiente un singolo oggetto più volte, il che aiuta nella creazione di [[assembly/it|assemblaggi]] complessi da sottoassiemi più piccoli e da più componenti riutilizzabili come viti, dadi e dispositivi di fissaggio simili.
An [[Std LinkMake|App::Link]] or just [[Std LinkMake|Link]] is a type of object that references another object, in the same document, or in another document. It is intended to be used in mechanical assemblies in which one object may appear multiple times, for example, screws and bolts, but also other complex sub-assemblies.


L'oggetto [[App_Link/it|App Link]] è stato introdotto di recente nella versione 0.19; in passato, si poteva ottenere una semplice duplicazione di oggetti con {{Button|[[File:Draft_Clone.svg|16px]] [[Draft_Clone/it|Clona]]}} di Draft, ma questa è una soluzione meno efficiente a causa della sua implementazione che essenzialmente crea una copia della [[Part_TopoShape/it|Forma (Shape)]] interna dell'oggetto sorgente. Invece, un link fa riferimento direttamente alla forma originale, quindi è più efficiente in termini di memoria.
For simple duplication of objects, see [[Draft Clone|Draft Clone]], [[Draft Array|Draft Array]], and [[Draft PathArray|Draft PathArray]]. The tools [[Draft LinkArray|Draft LinkArray]] and [[Draft PathLinkArray|Draft PathLinkArray]] create Links instead of simple copies.


<div class="mw-translate-fuzzy">
Links are intended to be used with full bodies. To create arrays of features inside the same [[PartDesign Body|PartDesign Body]], use [[PartDesign LinearPattern|PartDesign LinearPattern]], [[PartDesign PolarPattern|PartDesign PolarPattern]], and [[PartDesign_MultiTransform|PartDesign MultiTransform]].
I collegamenti si riferiscono al corpo completo. Per creare schiere di funzioni all'interno dello stesso [[PartDesign Body/it|Corpo di PartDesign]], usare [[PartDesign LinearPattern/it|Serie rettangolare]], [[PartDesign PolarPattern/it|Serie polare]], e [[PartDesign_MultiTransform/it|Multi trasformazione]].
</div>


When used with the [[File:Workbench_PartDesign.svg|24px]] [[PartDesign_Workbench|PartDesign Workbench]], Links are intended to be used with {{Button|[[File:PartDesign_Body.svg|16px]] [[PartDesign_Body|PartDesign Bodies]]}}, so it is recommended to set {{PropertyView|Display Mode Body}} to {{Value|Tip}} to select the features of the entire Body, and not the individual features. To create arrays of the internal [[PartDesign_Feature|PartDesign Features]], use {{Button|[[File:PartDesign_LinearPattern.svg|16px]] [[PartDesign_LinearPattern|PartDesign LinearPattern]]}}, {{Button|[[File:PartDesign_PolarPattern.svg|16px]] [[PartDesign_PolarPattern|PartDesign PolarPattern]]}}, and {{Button|[[File:PartDesign_MultiTransform.svg|16px]] [[PartDesign_MultiTransform|PartDesign MultiTransform]]}}.
==How to use==


The {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}} tool is not defined by a particular workbench, but by the base system, thus it is found in the {{MenuCommand|structure toolbar}} that is available in all [[Workbenches|workbenches]]. The Link object, used in conjunction with {{Button|[[File:Std_Part.svg|16px]] [[Std_Part|Std Part]]}} to group various objects, forms the basis of the [[File:Assembly3_workbench_icon.svg|24px]] [[Assembly3_Workbench|Assembly3]] and [[File:Assembly4_workbench_icon.svg|24px]] [[Assembly4_Workbench|Assembly4 Workbenches]].
# Select an object for which you wish to make a Link.
# Press the {{Button|[[Image:Std LinkMake.svg|16px]] [[Std LinkMake|Std LinkMake]]}} button. If no object is selected, an empty Link will be created.


==Properties==
== Utilizzo ==


Con selezione:
=== Data ===
# Selezionare un oggetto nella [[tree_view/it|vista ad albero]] o nella [[3D_view/it|vista 3D]] per il quale si desidera creare un link.
# Premere il pulsante {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake/it|Crea link]]}}. L'oggetto prodotto ha la stessa icona dell'oggetto originale, ma ha una freccia sovrapposta che indica che è un collegamento.


Without selection:
# If no object is selected, press the {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}} button to create an empty [[File:Link.svg|24px]] Link.
# Go to the [[property_editor|property editor]], then click on the {{PropertyData|Linked Object}} property to open the [[Selection_methods|Link selection dialog]] to choose an object, then press {{Button|OK}}.
# Instead of choosing an entire object in the [[tree_view|tree view]], you can also pick subelements (vertices, edges, or faces) of a single object in the [[3D_view|3D view]]. In this case, the Link will duplicate only these subelements, and the arrow overlay will be different. This can also be done with {{Button|[[File:Std_LinkMakeRelative.svg|16px]] [[Std_LinkMakeRelative|Std LinkMakeRelative]]}}.

[[File:Std_Link_tree_example.png]] [[File:Std_Link_example.png]]

{{Caption|(1) An object, (2) an empty Link, (3) a full Link to the first object (with overriding material), and (4) a Link to only some subelements of the object. The empty Link is not tied to the real object so it is not displayed in the [[3D_view|3D view]].}}

== Usage: external documents ==

# Start with a document that has at least one object which will be the source of the Link.
# Open a new document or an existing document. For easier handling, use {{Button|[[File:Std_TreeMultiDocument.svg|16px]] [[Std_TreeMultiDocument|Std TreeMultiDocument]]}} to show both documents in the [[tree_view|tree view]]. Before you proceed, [[Std_Save|save]] both documents. The Link won't be able to find its source and target unless both documents are saved on disk.
# In the first document, select the object that you wish to link; then switch tabs in the [[main_view_area|main view area]] to switch to the second document.
# Press {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}}. The produced object has the same icon as the original object, but has an additional arrow overlay indicating it is a Link coming from an external document.

{{Emphasis|Notes:}}
* When saving the document with the Link, it will also ask to [[Std_Save|save]] the source document which contains the original object.
* To include the original object in the document with the Link, use {{Button|[[File:Std_LinkImport.svg|16px]] [[Std_LinkImport|Std LinkImport]]}} or {{Button|[[File:Std_LinkImportAll.svg|16px]] [[Std_LinkImportAll|Std LinkImportAll]]}}.
* {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}} can be used on an existing Link object, in order to create a Link to a Link which ultimately resolves to the original object in the source document. This can be used with {{Button|[[File:Std_LinkMakeRelative.svg|16px]] [[Std_LinkMakeRelative|Std LinkMakeRelative]]}} to pick only certain subelements as well.

[[File:Std_Link_tree_documents_example.png]] [[File:Std_Link_documents_example.png]]

{{Caption|(1, 2) Two objects from a source document linked into a target document, (3) a Link to the second Link (with overriding material), and (4) a Link to the subelements of the second Link.}}

=== Dragging and dropping ===

Instead of switching document tabs, you can create Links by performing a drag and drop operation in the [[tree_view|tree view]]: select the source object from the first document, drag it, then drop it into the second document's name while holding the {{KEY|Alt}} key in the keyboard.

Dragging and dropping results in different actions depending on the modifier key that is held.
* Without modifier key it simply moves the object from one document to the other; an inclined arrow is shown in the cursor.
* Holding the {{KEY|Ctrl}} key copies the object; a plus sign is shown in the cursor.
* Holding the {{KEY|Alt}} key creates a Link; a pair of chain links is shown in the cursor.

For the {{KEY|Ctrl}} and {{KEY|Alt}} modifiers, dragging and dropping can also be done with a single document. That is, dragging an object and dropping it into the same document's name can be used to create multiple copies or multiple Links to it.

== Groups ==

{{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}} can be used on {{Button|[[File:Std_Part.svg|16px]] [[Std_Part|Std Parts]]}} in order to quickly duplicate groups of objects positioned in space, that is, [[assembly|assemblies]].

[[File:Std_Link_tree_Std_Part_example.png]]

{{Caption|Link created from a [[Std_Part|Std Part]]; the objects are not duplicated but they are listed under the original container and under the Link container.}}

A regular {{Button|[[File:Std_Group.svg|16px]] [[Std_Group|Std Group]]}} does not possess a {{PropertyData|Placement}} property, so it cannot control the position of the objects inside of it. However, when {{Button|[[File:Std_LinkMake.svg|16px]] [[Std_LinkMake|Std LinkMake]]}} is used with {{Button|[[File:Std_Group.svg|16px]] [[Std_Group|Std Group]]}}, the resulting Link behaves essentially like a {{Button|[[File:Std_Part.svg|16px]] [[Std_Part|Std Part]]}}, and can also be moved in space.

[[File:Std_Link_tree_Std_Group_example.png]] [[File:Std_Link_Std_Group_example.png]]

{{Caption|Link created from a [[Std_Group|Std Group]]; the objects are not duplicated but they are listed under the original container and under the Link container. The Link (with overriding material) can be moved in space, just like a [[Std_Part|Std Part]].}}

A Link to a {{Button|[[File:Std_Part.svg|16px]] [[Std_Part|Std Part]]}} will keep the visibility of the objects synchronized with the original Part; so if you hide one object in a Link, it will be hidden in all Links and in the original object. On the other hand a Link to a {{Button|[[File:Std_Group.svg|16px]] [[Std_Group|Std Group]]}} will allow independent control of the visibilities.

[[File:Std_Link_tree_Std_Part_visibility.png]] [[File:Std_Link_tree_Std_Group_visibility.png]]

{{Caption|Left: [[Std_Part|Std Part]] with two objects, and two Links to the Part; the visibility of the objects is synchronized. Right: [[Std_Group|Std Group]] with two objects, and two Links to the Group; the visibility of the objects is independently controlled in each group.}}

== Overriding appearance ==

When a Link is created, by default the {{PropertyView|Override Material}} is {{FALSE}}, so the Link will have the same appearance as the original {{PropertyData|Linked Object}}.

When {{PropertyView|Override Material}} is set to {{TRUE}}, the {{PropertyView|Shape Material}} property will now control the appearance of the Link.

Regardless of the state of {{PropertyView|Override Material}}, it is possible to individually set the appearance of the subelements (vertices, edges, faces) of a Link.
# Select the Link in the [[tree_view|tree view]]. Open the context menu (right-click), and pick {{MenuCommand|Override colors}}.
# Now pick the individual subelements that you want in the [[3D_view|3D view]], press {{Button|Edit}}, and change the properties including transparency.
# To remove the custom attributes, select the elements in the list, and press {{Button|Remove}}.
# When you are satisfied with the result, press {{Button|OK}} to close the dialog.

{{Emphasis|Note:}} as of v0.19, the coloring of the subelements is subject to the [[topological_naming_problem|topological naming problem]] so it should be done as the last modelling step, when the model is not subject to change any more.

[[File:Std_Link_override_color_example.png|500px]]

{{Caption|(1) An original object, (2) a Link with overriding material, and (3) a second Link with individual modified subelements.}}

== Link Array ==

{{Emphasis|See also:}} [[Draft_OrthoArray|Draft OrthoArray]].

When a Link is created, by default its {{PropertyData|Element Count}} is {{Value|0}}, so only a single Link object will be visible in the [[tree_view|tree view]].

Given that {{PropertyData|Show Element}} is {{TRUE}} by default, when {{PropertyData|Element Count}} is set to {{Value|1}} or more, automatically more Links will be created below the first one; each new Link can be placed in the desired position by changing its own {{PropertyData|Placement}} property.

In similar way, each element of the array can have its own appearance changed, either by the {{PropertyView|Override Material}} and {{PropertyView|Shape Material}} properties, or by using the {{MenuCommand|Override colors}} menu on the entire array and then selecting individual faces; this is described in [[#Overriding_appearance|Overriding appearance]].

[[File:Std_Link_tree_array_example.png]] [[File:Std_Link_array_example.png|500px]]

{{Caption|(1) Original object, and (2, 3, 4) a Link array with three elements, each in a different position. The first Link has overridden material and transparent faces, the other two have custom face colors.}}

Once you are satisfied with the placement and properties of the Link elements in the array, you may change {{PropertyData|Show Element}} to {{FALSE}} in order hide the individual Links in the [[tree_view|tree view]]; this has the benefit of making the system more responsive, particularly if you have many objects in the document.

When creating this type of Link array, you must place each of the elements manually; however, if you would like to use specific patterns to place the copies, you may use the array tools of the [[File:Workbench_Draft.svg|24px]] [[Draft_Module|Draft Workbench]], like {{Button|[[File:Draft_OrthoArray.svg|16px]] [[Draft_OrthoArray|Draft OrthoArray]]}}, {{Button|[[File:Draft_PolarArray.svg|16px]] [[Draft_PolarArray|Draft PolarArray]]}}, and {{Button|[[File:Draft_CircularArray.svg|16px]] [[Draft_CircularArray|Draft CircularArray]]}}; these commands can create normal copies or Link copies depending on the options at creation time.

== Visibility ==

When {{PropertyData|Show Element}} is {{TRUE}} and individual elements are listed in the [[tree_view|tree view]] in a [[#Link_Array|Link Array]], each Link can be shown or hidden by pressing the {{KEY|Space}} bar in the keyboard.

Another way to hide the individual elements is using the {{MenuCommand|Override colors}} menu.
# Select the array, open the {{MenuCommand|Override colors}} menu (right click).
# In the [[3D_view|3D view]], pick any subelement from any Link in the array.
# Press {{Button|Hide}}. An icon of an eye [[File:Invisible.svg|24px]] should appear, indicating that this element has been hidden from the [[3D_view|3D view]]. The object will temporarily show itself when the cursor hovers over the [[File:Invisible.svg|24px]] icon.
# You can click {{Button|OK}} to confirm the operation and close the dialog. The Link will remain hidden even if it is shown as visible in the [[tree_view|tree view]].

[[File:Std_Link_array_visibility_example.png]]

{{Caption|Element color dialog that is available when opening the context menu of a Link object in the tree view.}}

If you wish to restore the visibility of this array element, enter the dialog once more, pick the eye icon, then click on {{Button|Remove}} to remove the hidden status, and click {{Button|OK}} to confirm and close the dialog. The element will be visible in the [[3D_view|3D view]] again.

When the Link is for a {{Button|[[File:Std_Part.svg|16px]] [[Std_Part|Std Part]]}} or a {{Button|[[File:Std_Group.svg|16px]] [[Std_Part|Std Group]]}}, the {{MenuCommand|Override colors}} menu works in similar way as with arrays; it allows controlling the face color, entire object color, and visibility of the objects in the group.

[[File:Std_Link_Std_Part_visibility_example.png]] [[File:Std_Link_Std_Part_visibility_example_3D.png]]

{{Caption|A [[Std_Part|Std Part]] containing three objects, and a Link to that Part; in the Link, (1) the first object is made invisible, (2) the second object has some subelements with different colors, (3) the entire third object has a different color and level of transparency.}}

== Proprietà ==

An [[App_Link|App Link]] ({{incode|App::Link}} class) is derived from the basic [[App_DocumentObject|App DocumentObject]] ({{incode|App::DocumentObject}} class), therefore it has the latter's basic properties like {{PropertyData|Label}} and {{PropertyData|Label2}}.

The following are the specific properties available in the [[property editor|property editor]]. Hidden properties can be shown by using the {{MenuCommand|Show all}} command in the context menu of the [[property editor|property editor]].

=== Dati ===

{{TitleProperty| Link}}

<div class="mw-translate-fuzzy">
* {{PropertyData|Linked Object}}:
* {{PropertyData|Linked Object}}:
* {{PropertyData|Link Transform}}:
* {{PropertyData|Link Transform}}:
Line 33: Line 173:
* {{PropertyData|Element Count}}:
* {{PropertyData|Element Count}}:
* {{PropertyData|Scale}}:
* {{PropertyData|Scale}}:
</div>


{{TitleProperty|Base}}
It will additionally show the properties of the original {{PropertyData|Linked Object}}.


* {{PropertyData|Proxy|PythonObject|Hidden}}: a custom class associated with this object. This only exists for the [[Python|Python]] version. See [[Std_LinkMake#Scripting|Scripting]].
=== View ===


L'oggetto [[App_Link/it|App Link]] mostra inoltre le proprietà del {{PropertyData|Linked Object}} originale, quindi l'[[property_editor/it|editor delle proprietà]] può avere gruppi di proprietà come {{TitleProperty|Attachment}} , {{TitleProperty|Box}}, {{TitleProperty|Draft}} e così via.

===Vista===

{{TitleProperty| Link}}

<div class="mw-translate-fuzzy">
* {{PropertyView|Draw Style}}:
* {{PropertyView|Draw Style}}:
* {{PropertyView|Line Width}}:
* {{PropertyView|Line Width}}:
Line 44: Line 192:
* {{PropertyView|Selectable}}:
* {{PropertyView|Selectable}}:
* {{PropertyView|Shape Material}}:
* {{PropertyView|Shape Material}}:
</div>


* {{PropertyView|Shape Material|Material}}: this property includes sub-properties that describe the appearance of the object.
It will additionally show the view properties of the original {{PropertyData|Linked Object}}.
** {{PropertyView|Diffuse Color}}, it defaults to {{value|(0.4, 1.0, 1.0)}}, which is displayed as {{value|[102, 255, 255]}} on base 255, <span style="background-color:#6ff; color:#222; width:3em; height:12pt; padding: 2px 1em 2px;"> light blue </span>.
** {{PropertyView|Ambient Color}}, it defaults to {{value|(0.2, 0.2, 0.2)}}, which is displayed as {{value|[51, 51, 51]}} on base 255, <span style="background-color:#333; color:#eee; width:3em; height:12pt; padding: 2px 1em 2px;"> dark gray </span>.
** {{PropertyView|Specular Color}}, it defaults to {{value|(0.0, 0.0, 0.0)}}, which is displayed as {{value|[0, 0, 0]}} on base 255, <span style="background-color:#000; color:#eee; width:3em; height:12pt; padding: 2px 1em 2px;"> black </span>.
** {{PropertyView|Emissive Color}}, it defaults to {{value|(0.0, 0.0, 0.0)}}, which is displayed as {{value|[0, 0, 0]}} on base 255, <span style="background-color:#000; color:#eee; width:3em; height:12pt; padding: 2px 1em 2px;"> black </span>.
** {{PropertyView|Shininess}}, it defaults to {{Value|0.2}}
** {{PropertyView|Transparency}}, it defaults to {{Value|0.0}}.

{{TitleProperty|Base}}

* {{PropertyView|Child View Provider|PersistentObject|Hidden}}:
* {{PropertyView|Material List|MaterialList|Hidden}}: {{Emphasis|(read-only)}} if individual materials have been added, they will be listed here.
* {{PropertyView|Override Color List|ColorList|Hidden}}: {{Emphasis|(read-only)}} if the individual faces or edges of the link have been overridden they will be listed here.
* {{PropertyView|Override Material List|BoolList|Hidden}}: {{Emphasis|(read-only)}} if the individual materials of the link have been overridden they will be listed here.

{{TitleProperty|Display Options}}

* {{PropertyView|Display Mode|Enumeration}}: {{Value|'Link'}} or {{Value|'ChildView'}}.
* {{PropertyView|Show In Tree|Bool}}: see the information in [[App_FeaturePython|App FeaturePython]].
* {{PropertyView|Visibility|Bool}}: see the information in [[App_FeaturePython|App FeaturePython]].

{{TitleProperty|Selection}}

* {{PropertyView|On Top When Selected|Enumeration}}: see the information in [[App_FeaturePython|App FeaturePython]].
* {{PropertyView|Selection Style|Enumeration}}: see the information in [[App_FeaturePython|App FeaturePython]].

Mostra inoltre le proprietà Vista dell'originale {{PropertyData|Linked Object}}.

== Inheritance ==

An [[App_Link|App Link]] is formally an instance of the class {{incode|App::Link}}, whose parent is the basic [[App_DocumentObject|App DocumentObject]] ({{incode|App::DocumentObject}} class). It is a very low level object, which can be used with most other document objects.

[[File:FreeCAD_core_objects.svg|800px]]

{{Caption|Simplified diagram of the relationships between the core objects in the program. The {{incode|App::Link}} object is a core component of the system, it does not depend on any workbench, but it can be used with most objects created in all workbenches.}}

== Scripting ==

{{Emphasis|See also:}} [[FreeCAD Scripting Basics|FreeCAD Scripting Basics]], and [[scripted objects|scripted objects]].

See [[Part_Feature|Part Feature]] for the general information.

An App Link is created with the {{incode|addObject()}} method of the document. It can define its {{PropertyData|Linked Object}} by overriding its {{incode|LinkedObject}} attribute, or by using its {{incode|setLink}} method.
{{Code|code=
import FreeCAD as App

doc = App.newDocument()
bod1 = App.ActiveDocument.addObject("Part::Box", "Box")
bod2 = App.ActiveDocument.addObject("Part::Cylinder", "Cylinder")
bod1.Placement.Base = App.Vector(10, 0, 0)
bod2.Placement.Base = App.Vector(0, 10, 0)

obj1 = App.ActiveDocument.addObject("App::Link", "Link")
obj2 = App.ActiveDocument.addObject("App::Link", "Link")

obj1.LinkedObject = bod1
obj2.setLink(bod2)
obj1.Placement.Base = App.Vector(-10, -10, 0)
obj2.Placement.Base = App.Vector(10, -10, 0)
obj1.ViewObject.OverrideMaterial = True
App.ActiveDocument.recompute()
}}

The basic {{incode|App::Link}} doesn't have a Proxy object so it can't be fully used for sub-classing.

Therefore, for [[Python|Python]] subclassing, you should create the {{incode|App::LinkPython}} object.

{{Code|code=
import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("App::LinkPython", "Link")
obj.Label = "Custom label"
}}

== Further reading ==

The [[App_Link|App Link]] object was introduced after 2 years of development and prototyping. This component was thought and developed almost single-handedly by user {{Emphasis|realthunder}}. The motivations and design implementations behind this project are described in his GitHub page, [https://github.com/realthunder/FreeCAD_assembly3/wiki/Link Link]. In order to accomplish this feature, several core changes to FreeCAD were made; these were also extensively documented in [https://github.com/realthunder/FreeCAD_assembly3/wiki/Core-Changes Core-Changes].

The App Link project started after the redesign of the [[PartDesign Workbench|PartDesign Workbench]] was complete in v0.17. The history of App Link can be traced to some essential forum threads:
* [https://forum.freecadweb.org/viewtopic.php?f=19&t=21505 Why an object can only be inside one App::Part?] (March 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=10&t=21586 Introducing App::Link/XLink] (March 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=20&t=22216 Links] (May 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=20&t=23015 Realthunder Link implementation: Architecture discussion] (June 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=17&t=23419 PR #876: Link, stage one, context aware selection] (July 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=17&t=23626 Preview: Link, stage two, API groundwork] (July 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=20&t=25712 Assembly3 preview] (December 2017)
* [https://forum.freecadweb.org/viewtopic.php?f=10&t=29542 Merging of my Link branch] (June 2018)

Finally, the pull request and merge happened:
* [https://forum.freecadweb.org/viewtopic.php?f=27&t=38621 App::Link: the big merge], old thread (July 2019), [https://github.com/FreeCAD/FreeCAD/pull/2350 pull request #2350] (the BIG merge), [https://github.com/realthunder/FreeCAD/tree/LinkMerge LinkMerge branch].
* [https://forum.freecadweb.org/viewtopic.php?f=8&t=37757 App::Link: the big merge], main thread (July 2019)
* [https://forum.freecadweb.org/viewtopic.php?p=329054#p329054 A simple path description of Link, 019, Link stage, Asm3, merge?] (August 2019)
* [https://forum.freecadweb.org/viewtopic.php?f=17&t=39672 PR#2559: expose link and navigation actions], an introduction to the Link feature in 0.19 (September 2019).


{{Docnav
|[[Std_Group|Std Group]]
|[[Std_LinkMakeRelative|Std LinkMakeRelative]]
|[[Std_Base|Std Base]]
|IconL=Std_Group.svg
|IconR=Std_LinkMakeRelative.svg
|IconC=Freecad.svg
}}


{{Std Base navi{{#translation:}}}}
{{Userdocnavi}}
{{Userdocnavi{{#translation:}}}}
{{clear}}

Revision as of 14:19, 2 December 2020

Crea link

Posizione nel menu
None
Ambiente
Tutti
Avvio veloce
Nessuno
Introdotto nella versione
0.19
Vedere anche
Std Part, Std Group, PartDesign Body

Descrizione

Crea link crea un App Link (classe App::Link), che è un tipo di oggetto che fa riferimento o collega ad un altro oggetto, nello stesso documento o in un altro documento. È appositamente progettato per duplicare in modo efficiente un singolo oggetto più volte, il che aiuta nella creazione di assemblaggi complessi da sottoassiemi più piccoli e da più componenti riutilizzabili come viti, dadi e dispositivi di fissaggio simili.

L'oggetto App Link è stato introdotto di recente nella versione 0.19; in passato, si poteva ottenere una semplice duplicazione di oggetti con Clona di Draft, ma questa è una soluzione meno efficiente a causa della sua implementazione che essenzialmente crea una copia della Forma (Shape) interna dell'oggetto sorgente. Invece, un link fa riferimento direttamente alla forma originale, quindi è più efficiente in termini di memoria.

I collegamenti si riferiscono al corpo completo. Per creare schiere di funzioni all'interno dello stesso Corpo di PartDesign, usare Serie rettangolare, Serie polare, e Multi trasformazione.

When used with the PartDesign Workbench, Links are intended to be used with PartDesign Bodies, so it is recommended to set VistaDisplay Mode Body to Tip to select the features of the entire Body, and not the individual features. To create arrays of the internal PartDesign Features, use PartDesign LinearPattern, PartDesign PolarPattern, and PartDesign MultiTransform.

The Std LinkMake tool is not defined by a particular workbench, but by the base system, thus it is found in the structure toolbar that is available in all workbenches. The Link object, used in conjunction with Std Part to group various objects, forms the basis of the Assembly3 and Assembly4 Workbenches.

Utilizzo

Con selezione:

  1. Selezionare un oggetto nella vista ad albero o nella vista 3D per il quale si desidera creare un link.
  2. Premere il pulsante Crea link. L'oggetto prodotto ha la stessa icona dell'oggetto originale, ma ha una freccia sovrapposta che indica che è un collegamento.

Without selection:

  1. If no object is selected, press the Std LinkMake button to create an empty Link.
  2. Go to the property editor, then click on the DatiLinked Object property to open the Link selection dialog to choose an object, then press OK.
  3. Instead of choosing an entire object in the tree view, you can also pick subelements (vertices, edges, or faces) of a single object in the 3D view. In this case, the Link will duplicate only these subelements, and the arrow overlay will be different. This can also be done with Std LinkMakeRelative.

(1) An object, (2) an empty Link, (3) a full Link to the first object (with overriding material), and (4) a Link to only some subelements of the object. The empty Link is not tied to the real object so it is not displayed in the 3D view.

Usage: external documents

  1. Start with a document that has at least one object which will be the source of the Link.
  2. Open a new document or an existing document. For easier handling, use Std TreeMultiDocument to show both documents in the tree view. Before you proceed, save both documents. The Link won't be able to find its source and target unless both documents are saved on disk.
  3. In the first document, select the object that you wish to link; then switch tabs in the main view area to switch to the second document.
  4. Press Std LinkMake. The produced object has the same icon as the original object, but has an additional arrow overlay indicating it is a Link coming from an external document.

Notes:

  • When saving the document with the Link, it will also ask to save the source document which contains the original object.
  • To include the original object in the document with the Link, use Std LinkImport or Std LinkImportAll.
  • Std LinkMake can be used on an existing Link object, in order to create a Link to a Link which ultimately resolves to the original object in the source document. This can be used with Std LinkMakeRelative to pick only certain subelements as well.

(1, 2) Two objects from a source document linked into a target document, (3) a Link to the second Link (with overriding material), and (4) a Link to the subelements of the second Link.

Dragging and dropping

Instead of switching document tabs, you can create Links by performing a drag and drop operation in the tree view: select the source object from the first document, drag it, then drop it into the second document's name while holding the Alt key in the keyboard.

Dragging and dropping results in different actions depending on the modifier key that is held.

  • Without modifier key it simply moves the object from one document to the other; an inclined arrow is shown in the cursor.
  • Holding the Ctrl key copies the object; a plus sign is shown in the cursor.
  • Holding the Alt key creates a Link; a pair of chain links is shown in the cursor.

For the Ctrl and Alt modifiers, dragging and dropping can also be done with a single document. That is, dragging an object and dropping it into the same document's name can be used to create multiple copies or multiple Links to it.

Groups

Std LinkMake can be used on Std Parts in order to quickly duplicate groups of objects positioned in space, that is, assemblies.

Link created from a Std Part; the objects are not duplicated but they are listed under the original container and under the Link container.

A regular Std Group does not possess a DatiPlacement property, so it cannot control the position of the objects inside of it. However, when Std LinkMake is used with Std Group, the resulting Link behaves essentially like a Std Part, and can also be moved in space.

Link created from a Std Group; the objects are not duplicated but they are listed under the original container and under the Link container. The Link (with overriding material) can be moved in space, just like a Std Part.

A Link to a Std Part will keep the visibility of the objects synchronized with the original Part; so if you hide one object in a Link, it will be hidden in all Links and in the original object. On the other hand a Link to a Std Group will allow independent control of the visibilities.

Left: Std Part with two objects, and two Links to the Part; the visibility of the objects is synchronized. Right: Std Group with two objects, and two Links to the Group; the visibility of the objects is independently controlled in each group.

Overriding appearance

When a Link is created, by default the VistaOverride Material is false, so the Link will have the same appearance as the original DatiLinked Object.

When VistaOverride Material is set to true, the VistaShape Material property will now control the appearance of the Link.

Regardless of the state of VistaOverride Material, it is possible to individually set the appearance of the subelements (vertices, edges, faces) of a Link.

  1. Select the Link in the tree view. Open the context menu (right-click), and pick Override colors.
  2. Now pick the individual subelements that you want in the 3D view, press Edit, and change the properties including transparency.
  3. To remove the custom attributes, select the elements in the list, and press Remove.
  4. When you are satisfied with the result, press OK to close the dialog.

Note: as of v0.19, the coloring of the subelements is subject to the topological naming problem so it should be done as the last modelling step, when the model is not subject to change any more.

(1) An original object, (2) a Link with overriding material, and (3) a second Link with individual modified subelements.

Link Array

See also: Draft OrthoArray.

When a Link is created, by default its DatiElement Count is 0, so only a single Link object will be visible in the tree view.

Given that DatiShow Element is true by default, when DatiElement Count is set to 1 or more, automatically more Links will be created below the first one; each new Link can be placed in the desired position by changing its own DatiPlacement property.

In similar way, each element of the array can have its own appearance changed, either by the VistaOverride Material and VistaShape Material properties, or by using the Override colors menu on the entire array and then selecting individual faces; this is described in Overriding appearance.

(1) Original object, and (2, 3, 4) a Link array with three elements, each in a different position. The first Link has overridden material and transparent faces, the other two have custom face colors.

Once you are satisfied with the placement and properties of the Link elements in the array, you may change DatiShow Element to false in order hide the individual Links in the tree view; this has the benefit of making the system more responsive, particularly if you have many objects in the document.

When creating this type of Link array, you must place each of the elements manually; however, if you would like to use specific patterns to place the copies, you may use the array tools of the Draft Workbench, like Draft OrthoArray, Draft PolarArray, and Draft CircularArray; these commands can create normal copies or Link copies depending on the options at creation time.

Visibility

When DatiShow Element is true and individual elements are listed in the tree view in a Link Array, each Link can be shown or hidden by pressing the Space bar in the keyboard.

Another way to hide the individual elements is using the Override colors menu.

  1. Select the array, open the Override colors menu (right click).
  2. In the 3D view, pick any subelement from any Link in the array.
  3. Press Hide. An icon of an eye should appear, indicating that this element has been hidden from the 3D view. The object will temporarily show itself when the cursor hovers over the icon.
  4. You can click OK to confirm the operation and close the dialog. The Link will remain hidden even if it is shown as visible in the tree view.

Element color dialog that is available when opening the context menu of a Link object in the tree view.

If you wish to restore the visibility of this array element, enter the dialog once more, pick the eye icon, then click on Remove to remove the hidden status, and click OK to confirm and close the dialog. The element will be visible in the 3D view again.

When the Link is for a Std Part or a Std Group, the Override colors menu works in similar way as with arrays; it allows controlling the face color, entire object color, and visibility of the objects in the group.

A Std Part containing three objects, and a Link to that Part; in the Link, (1) the first object is made invisible, (2) the second object has some subelements with different colors, (3) the entire third object has a different color and level of transparency.

Proprietà

An App Link (App::Link class) is derived from the basic App DocumentObject (App::DocumentObject class), therefore it has the latter's basic properties like DatiLabel and DatiLabel2.

The following are the specific properties available in the property editor. Hidden properties can be shown by using the Show all command in the context menu of the property editor.

Dati

Link

  • DatiLinked Object:
  • DatiLink Transform:
  • DatiPlacement:
  • DatiSub Elements:
  • DatiShow Elements:
  • DatiElement Count:
  • DatiScale:

Base

  • Dati (Hidden)Proxy (PythonObject): a custom class associated with this object. This only exists for the Python version. See Scripting.

L'oggetto App Link mostra inoltre le proprietà del DatiLinked Object originale, quindi l'editor delle proprietà può avere gruppi di proprietà come Attachment , Box, Draft e così via.

Vista

Link

  • VistaDraw Style:
  • VistaLine Width:
  • VistaOverride Material:
  • VistaPoint Size:
  • VistaSelectable:
  • VistaShape Material:
  • VistaShape Material (Material): this property includes sub-properties that describe the appearance of the object.
    • VistaDiffuse Color, it defaults to (0.4, 1.0, 1.0), which is displayed as [102, 255, 255] on base 255, light blue .
    • VistaAmbient Color, it defaults to (0.2, 0.2, 0.2), which is displayed as [51, 51, 51] on base 255, dark gray .
    • VistaSpecular Color, it defaults to (0.0, 0.0, 0.0), which is displayed as [0, 0, 0] on base 255, black .
    • VistaEmissive Color, it defaults to (0.0, 0.0, 0.0), which is displayed as [0, 0, 0] on base 255, black .
    • VistaShininess, it defaults to 0.2
    • VistaTransparency, it defaults to 0.0.

Base

  • Vista (Hidden)Child View Provider (PersistentObject):
  • Vista (Hidden)Material List (MaterialList): (read-only) if individual materials have been added, they will be listed here.
  • Vista (Hidden)Override Color List (ColorList): (read-only) if the individual faces or edges of the link have been overridden they will be listed here.
  • Vista (Hidden)Override Material List (BoolList): (read-only) if the individual materials of the link have been overridden they will be listed here.

Display Options

  • VistaDisplay Mode (Enumeration): 'Link' or 'ChildView'.
  • VistaShow In Tree (Bool): see the information in App FeaturePython.
  • VistaVisibility (Bool): see the information in App FeaturePython.

Selection

Mostra inoltre le proprietà Vista dell'originale DatiLinked Object.

Inheritance

An App Link is formally an instance of the class App::Link, whose parent is the basic App DocumentObject (App::DocumentObject class). It is a very low level object, which can be used with most other document objects.

Simplified diagram of the relationships between the core objects in the program. The App::Link object is a core component of the system, it does not depend on any workbench, but it can be used with most objects created in all workbenches.

Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

See Part Feature for the general information.

An App Link is created with the addObject() method of the document. It can define its DatiLinked Object by overriding its LinkedObject attribute, or by using its setLink method.

import FreeCAD as App

doc = App.newDocument()
bod1 = App.ActiveDocument.addObject("Part::Box", "Box")
bod2 = App.ActiveDocument.addObject("Part::Cylinder", "Cylinder")
bod1.Placement.Base = App.Vector(10, 0, 0)
bod2.Placement.Base = App.Vector(0, 10, 0)

obj1 = App.ActiveDocument.addObject("App::Link", "Link")
obj2 = App.ActiveDocument.addObject("App::Link", "Link")

obj1.LinkedObject = bod1
obj2.setLink(bod2)
obj1.Placement.Base = App.Vector(-10, -10, 0)
obj2.Placement.Base = App.Vector(10, -10, 0)
obj1.ViewObject.OverrideMaterial = True
App.ActiveDocument.recompute()

The basic App::Link doesn't have a Proxy object so it can't be fully used for sub-classing.

Therefore, for Python subclassing, you should create the App::LinkPython object.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("App::LinkPython", "Link")
obj.Label = "Custom label"

Further reading

The App Link object was introduced after 2 years of development and prototyping. This component was thought and developed almost single-handedly by user realthunder. The motivations and design implementations behind this project are described in his GitHub page, Link. In order to accomplish this feature, several core changes to FreeCAD were made; these were also extensively documented in Core-Changes.

The App Link project started after the redesign of the PartDesign Workbench was complete in v0.17. The history of App Link can be traced to some essential forum threads:

Finally, the pull request and merge happened: