Making a selection

In order to make a selection, the program must be in the selection-enabled mode. This mode is the default mode of the program and only a limited number of functions changes this mode into a selection-disabled mode. The selection-enabled mode is identified by the mouse cursor that looks like a diagonally oriented arrow with a small square attached to the tip of the arrow. Once this cursor is on the screen, it is possible to make selections freely.

There are two basic ways to make a new selection: using the mouse or typing a command on the command line. In both ways it is a piece of cake.

In addition, a selection can also be made via filters. That means, that the user specifies a condition that should be fulfilled by all selected entities. For example, the user may specify the condition that the cross-section must be a rolled IPE 300. The filter-controlled selection then looks for and selects all 1D members with such a cross-section.

Making a selection by the mouse cursor

When using the mouse cursor, there are several selection modes:

single selection	One entity is selected each time the user clicks the mouse button.
intersection line	The user draws a line (or a polygon) on the screen. The program selects all entities that have an intersection with the drawn line.
rectangular cut-out	The user draws a rectangle on the screen. The program selects all entities located inside the rectangle or overlapping it (see the paragraph below for details about this selection mode).
polygonal cut-out	The user draws a closed polygon on the screen. The program selects all entities located inside the polygon.
working plane	The program selects all entities located in the current working plane.
select-all	All currently displayed entities are selected
previous	Activates the last made selection.

How to activate the required selection mode:

selection mode		via toolbar Selections	via menu Tools > Selections
Single selection	$image\Icon_Selection_SINGLE.gif$	click button [Selection by mouse]	call function Selection by mouse
Intersection line	$image\Icon_Selection_LINE.gif$	click button [Selection by cut-out]	call function Selection by intersection line
Rectangular cut-out	$image\Icon_Selection_RECTANGLE.gif$	click button [Selection by intersection line]	call function Selection by cut-out
Polygonal cut-out	$image\Icon_Selection_POLY.gif$	click button [Selection by polygonal cut-out]	call function Selection by polygonal cut-out
Working plane	$image\Icon_Selection_Workplane.gif$	click button [Select by working plane]	call function Select by working plane
Select all	$image\Icon_Selection_ALL.gif$	click button [Select all]	call function Select all
Previous	$image\Icon_Selection_BACK.gif$	click button [Previous selection]	call function Previous selection
Single selection mode toggle		swaps between "First found" and "All found" mode	see paragraph Selection of entities with overlapping edges
Selection mode toggle		swaps between "Select" and "Deselect" mode	see topic Removing the entities from selection
Visibility selection mode		swaps between "normal" selection mode and a special mode for OPGL	see paragraph Visibility selection mode see also paragraph Visibility selection acceleration

Single selection

In order to make a selection, the user has to:

place the mouse cursor on the entity he/she wants to select,
click the left mouse button.

That is all that is necessary to make a selection by mouse. To add another entity, the user just puts the cursor on another entity and clicks the left mouse button.

Intersection line

When this mode is invoked, all entities that are intersected by a defined line are added into the selection. The line may be either a single straight line or a polygon consisting of straight lines.

The procedure to define a polygon

Position the mouse cursor to the place where the polygon should start.
Click the left mouse button.
Position the mouse cursor where the end point of the polygon line segment should be located.
Click the left mouse button.
Repeat the previous two steps as many times as required.
Close the polygon, ie. either
1. press [ESC] key, or
2. invoke the pop-up menu, select End polyline command and run it, or
3. define the last point with a double-click on the left mouse button.

Cut-out

This mode enables the user to select all entities located inside a mouse defined cut-out. There are two different kinds of the cut-out. The first one serves for selection of entities located fully inside it. The other one can be used to select entities that are both fully inside and overlap the cut-out.

The procedure to define a cut-out that selects inside-located entities only

Place the mouse cursor to the TOP LEFT corner of the rectangular cut-out.
Press the left mouse button and hold it down.
Drag the mouse to the BOTTOM RIGHT corner of the rectangular cut-out.
Release the button.

The procedure to define a cut-out selecting both inside-located and overlapping entities

Place the mouse cursor to the TOP RIGHT corner of the rectangular cut-out.
Press the left mouse button and hold it down.
Drag the mouse to the BOTTOM LEFT corner of the rectangular cut-out.
Release the button.

Polygon

This mode is similar to the previous one. The difference is that the user draws an arbitrarily shaped closed polygon instead of a simple rectangle.

The procedure to define a polygonal cut-out

Position the mouse cursor to the place where the polygon should start.
Click the left mouse button.
Position the mouse cursor where the next vertex of the polygon should be located.
Click the left mouse button.
Repeat the previous two steps as many times as required.
Close the polygon:
1. either press [ESC] key, or
2. invoke the pop-up menu, select Close polygon command and run it.

Working plane

In this mode, the program automatically selects all entities located in the current working plane.

Select-all

All displayed entities are automatically selected.

Selection of entities with overlapping edges

In a real-life model it is frequent situation that several entities (e.g. beams, walls) meet in one place (joint, corner). In that case it may be difficult to select the proper entity, because when you place the mouse cursor over the intersection of these entities, the program does not know, which one to select. To solve such situations, the program offers a special toggle: Single selection. This switch enables you to work in two modes:

First found

In this mode, the first entity found by the selection algorithm is selected (usually, it is the entity that was input first).

All found

In this mode, the program finds all entities under cursor and offers you a list of them so that you may decide yourself which one(s) should be selected.

Imagine a simple model of three walls.

$image\SelectionOverlappingEdges1.gif$

If you place the cursor over the corner in which the three walls meet and click the left mouse button, the program opens a small dialogue with a list of found entities.

You may roll the mouse cursor over the list. The entity over which the cursor is just placed is highlighted in the graphical screen, so it is easy to find out which entity is which.

$image\SelectionOverlappingEdges2.gif$

If you want to select a particular entity, just click on its name in the list. You may select as many entities as you want.

$image\SelectionOverlappingEdges3.gif$

When you press the green-mark button, the selection is confirmed.

$image\SelectionOverlappingEdges4.gif$

Visibility selection mode

In the "normal" selection mode, you must select an edge of an entity in order to select it.

However, if the Visibility selection mode is activated, you may just put the mouse cursor anywhere on the displayed member and it can be selected. The only precondition is that Rendering display style is active.

The Single selection mode toggle is taken into account in the Visibility selection mode.

Examples (the little cross in the blue circle indicates the position of the mouse cursor):

A) Single selection mode toggle set to FIRST FOUND

B) Single selection mode toggle set to ALL FOUND

Please note that the cursor changes its shape when the program is in the visibility selection mode.

Visibility selection acceleration

When you use the Visibility selection mode, the acceleration can be used to speed up the manipulation with large models. However, it is important to know that the final effect of the acceleration depends on the model of the structure and that the acceleration may, under certain circumstances, even slow down the program response.

The principle of the acceleration is that the model that is displayed in the graphical window is converted to an OPGL scene (a special graphical scene optimised for the graphical card) that is usually processed faster by the graphical card. However, in order to allow for selections, the OPGL scene must handle also a list of all members that are displayed. And this may be the core of the problem. If the "workload" related to the management of this list exceeds the "workload" related to displaying of the graphical scene, the effect of the acceleration may be negative. This can be better understood on the following example.

Let us have a structure model composed of 1000 members (beams and columns).

A) All the members have a rectangular cross-section. It is quite a simple task for the graphical card to display such a simple shape (even if it is repeated 1000 times). On the other hand, the maintenance of the list of 1000 items is a rather complex matter. As a result, if the acceleration is ON, the response of the program will be most likely slower.

B) All the members have a circular (pipe) cross-section. It is more complex task for the graphical card to display such a shape. As a result, the acceleration will probably have no effect. In other words, the time saved during the display operation equals the time needed for the management of the list of the members.

C) All the members have a cross-section of a complex shape (e.g. a complex aluminium profile). In this case, the time savings reached due to faster display operation are much greater than the time-losses due to the management of the list of the members. Which means that the acceleration has a positive effect.

The acceleration can be switched on/off in menu Tools > Selection.

Filter-controlled selection

The filter-controlled selection is useful if the user wants to select all entities that meet a specific condition. This type of selection is described in the following chapter.

Making a selection from the command line

A selection can be also made (sometimes very effectively) from the program’s command line.

The procedure is similarly simple as the "mouse procedure". The user types a command on the command line and the selection is made.

Command syntax

SEL [switch] parameter [parameter2] [parameter3] [etc.]

SELM [Enter]

name1 [Enter]

name2 [Enter]

...

END [Enter]

The latter alternative provides fo multiple selections. SELM + [Enter] starts the multi-selection mode. Then you can type the names of required entities one by one – each one followed by [Enter] key. The selection can be completed with command END (followed by [Enter] key).

Switch

switch	meaning
+	adds into selection
-	subtracts from the current selection
\|	inverts the current selection

Parameter

parameter	example	description
entity name	SEL BEAM23	selects entity named BEAM23
entity name with a wildcard	SEL BEAM2?	selects all entities whose name starts with BEAM2 and is followed with a single character
	SEL B?	if 1D members are named B and numbered, this command selects all "one-digit" 1D members
	SEL B??	if 1D members are named B and numbered, this command selects all "two-digit" 1D members
	SEL B*	selects all entities whose name starts with letter B
	SEL B1 B2	selects entities named B1 and B2
NONE	SEL NONE	clears the selection

Examples

sel none	clears the selection
sel *	selects all entities
sel N1	selects entity N1
sel + N*	adds into the current selection entities whose name starts with N
sel – B*	removes from the current selection entities whose name starts with B
sel \| B1	inverts entity B1 in the selection (i.e. if the entity WAS in the selection, it is removed; if the entity WAS NOT in the selection, it is added)

Making a selection of a mesh node from the command line

To select a mesh node by its number, command SELMN can be used.

Procedure to select required mesh nodes

1. Type command SELMN in the SCIA Engineer command line and press Enter.

2. The selection function starts.

3. Type the number of the node to be selected and press Enter. The node is marked with an arrow.

4 . If required, repeat step 3.

5. Press Esc to end the command.

IMPORTANT: In order to see the arrow denoting the selected node(s) it is necessary to switch ON the appropriate flag in the View parameters settings Dialogue - Miscellaneous > Calculation info > Display arrow on mesh elements.

Procedure to remove the highlighting arrow from selected mesh nodes

1. Select the arrow or the accompanying text with the mouse cursor.

2. Press key Delete on your keyboard OR use the Delete function from the pop-up menu OR use the Delete function from the Modify menu.