====== Snap function ======

<note tip>
Snapping = the action which fits a newly created or an edited object vertex exactly onto a nearby reference position. \\
This reference position can be another object vertex or construction point/line.
\\ \\
The **snap indicator** shows a red circle in case of a snapped vertex.
</note> 

<note important>Snapping is only possible if the CRS of the edited dataset is the same as the MapCanavas CRS. \\ More about coordinate systems can be reviewed here : [[224:technology:core:crs|]].</note>

===== Snap to Objects =====

While editing, Orbit will snap to object points. \\
{{orbit_desktop:tools:editing:snap_detail.png?50nolink|}}
\\ The snap behaviour depends on the [[224:desktop:preferences:editing|editing preferences]]. It's important to know to which objects will be snapped:
  * To selected objects only. To snap on an object point, the target object needs to be selected. Otherwise the point will not snap to the exact position of the vertex.
  * To all objects within the selected dataset. No selection required.
  * To all visible datasets. No selection required.

Not all [[224:desktop:tools:edit|Edit tools]] contain snap. Below the most important **"snap"-tools** are listed.

^  Function  ^  Action  ^  Example  ^^
| {{43:orbitgis:data2:editing:edit:obj_create_new_object.gif?20x20&nolink}} \\ New object | Click nearby an existing object point to snap | {{:orbit_desktop:tools:editing:snap_newobject1.png?nolink}} | {{:orbit_desktop:tools:editing:snap_newobject2.png?nolink}} |
| {{43:orbitgis:data2:editing:edit:editvertex_point_move.gif?20x20&nolink}} \\ Move a point | Click and drag point(s) to a snappable position. | {{:orbit_desktop:tools:editing:snap_move1.png?nolink}} | {{:orbit_desktop:tools:editing:snap_move2.png?nolink}} |
| ::: | If more object points of different objects overlay, only the vertices of selected objects will be moved. | {{orbit_desktop:tools:editing:snap_move4.png?nolink}}  | {{:orbit_desktop:tools:editing:snap_move3.png?nolink}}  |
| {{43:orbitgis:data2:editing:edit:editvertex_point_add.gif?20x20&nolink}} \\ Add a point | Click a new point on an intersection line and drag to a snappable position | {{:orbit_desktop:tools:editing:snap_addpoint1.png?nolink}}  | {{:orbit_desktop:tools:editing:snap_addpoint2.png?nolink}}  |
| {{43:orbitgis:data2:editing:edit:editvertex_part_add.gif?20x20&nolink}} \\ Add a part | Click a position for every point of the area. Each click nearby a snappable postition will snap \\ on the existing vertices. | {{:orbit_desktop:tools:editing:snap_addpart1.png?nolink}} | {{:orbit_desktop:tools:editing:snap_addpart2.png?nolink}} |
| {{43:orbitgis:data2:editing:edit:editvertex_cut.gif?nolink}} \\ Cut Objects | When cutting an object into two parts, orbit creates two neighboring objects. \\ The common object points are snapped when the object is cut. | {{:orbit_desktop:tools:editing:snap_cut1.png?nolink}} | {{:orbit_desktop:tools:editing:snap_cut2.png?nolink}} |
| {{43:orbitgis:data2:editing:edit:obj_merge.gif?20x20&nolink}} \\ Merge Objects | To merge objects into objects with only one part, it's necessary that object points of neighboring \\ objects are common. Common objects can be created by snapping them to each other. | {{:orbit_desktop:tools:editing:snap_cut2.png?nolink}} | {{:orbit_desktop:tools:editing:snap_cut1.png?nolink}} |

===== Snap to Constructions =====

The [[224:desktop:tools:constructions|construction tools]] can be used to snap object points while editing. \\
In the [[224:desktop:preferences:editing|editing preferences]] it is possible to enable snap to both **Construction points** and **Construction lines**.

^  Function  ^  Action  ^  Edit Tools  ^  Example  ^^
| {{43:orbitgis:data2:editing:constructions:con_cpt_visual.gif?20x20&nolink}} Snap to Construction Points |  Use the position of the construction points to edit object points.  |  {{43:orbitgis:data2:editing:edit:obj_create_new_object.gif?20x20&nolink}} Create new object  | {{:orbit_desktop:tools:editing:snap_constructionpoint.png?200nolink}} | {{:orbit_desktop:tools:editing:snap_constructionpoint1.png?200nolink}} |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_point_move.gif?20x20&nolink}} Move a point  | ::: | ::: |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_point_add.gif?20x20&nolink}} Add a point  | ::: | ::: |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_part_add.gif?20x20&nolink}} Add a part  | ::: | ::: |
| {{43:orbitgis:data2:editing:constructions:con_cln_visual.gif?20x20&nolink}} Snap to Construction Lines |  Edit object points using positions of the construction lines.  |  {{43:orbitgis:data2:editing:edit:obj_create_new_object.gif?20x20&nolink}} Create new object  |   {{:orbit_desktop:tools:editing:snap_constructionline.png?200nolink}} | {{:orbit_desktop:tools:editing:snap_constructionline1.png?200nolink}} |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_point_move.gif?20x20&nolink}} Move a point  | ::: | ::: |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_point_add.gif?20x20&nolink}} Add a point  | ::: | ::: |
| ::: | ::: |  {{43:orbitgis:data2:editing:edit:editvertex_part_add.gif?20x20&nolink}} Add a part  | ::: | ::: |