Grab Mode
Alternative mode for more intuitive rotation, shifting or zooming during exploration of a crystal or molecular structure
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The "grab mode" is an alternative to the several "tracking modes" that have been
well-known since earlier Diamond versions. The advantage is that you are able to
rotate, shift, or zoom in/out without the need to change between the several tracking
modes. The "sub-modes" of grab mode are:
(1) Rotation with left mouse button.
(2) Shifting with right mouse button.
(3) Changing enlargement factor or camera distance with mouse wheel.
(4) Several options available with mouse button double click.
The "Grab mode" can be activated with the (here yellow highlighted) toolbar button or with the Grab Mode command in the Edit menu. The arrow symbol right beneath can be used to terminate the "Grab mode" and return to default "Select and Edit" mode:

Rotation with left mouse button
Unlike in the "tracking modes", known from prior Diamond versions (and still available
in the current version), the rotation is here performed as an "arcball" rotation.
That means - depending on the current mouse pointer position - you rotate an object
or a virtual point across a hemisphere.
(a)
If no object (atom, bond) is "grabbed" (i.e. there has been no atom or bond
under the mouse cursor when you pressed down the left mouse button): Rotation of a virtual point on the surface
of a hemisphere with the radius of the longest distance of an atom from the center
of rotation.
(b)
If an atom or bond has been grabbed: Rotation of that object on a hemisphere with
the radius of the object's distance from the center of rotation.
The advantage of this "arcball" rotation over the traditional tracking modes "rotation along xy-axis" and "rotation along z-axis" that you have been knowing from previous
Diamond versions is that it considers all three rotation axes x,y,z - depending
on the current mouse position, whereas tracking mode rotation is independent from mouse position and considers only horizontal
and vertical mouse movement increments.
If the mouse position is outside the hemisphere -- that typically means at the edges
of the structure picture --, the arcball rotation is along the z-axis only. The
closer the mouse cursor is to the center of rotation (usually center of structure
picture), the higher the amounts of rotation along x- and y-axis.
Shifting with right mouse button
Pressing down the right mouse button initiates shifting mode. The structure picture follows the mouse position horizontally
and vertically, rsp. Like in tracking mode "Shift XY" the 2D-depiction of the center
of rotation is moved along the x- and y-axis of the Diamond view.
Selecting objects in grab mode
Although "Grab mode" (mouse cursor shows a hand symbol) is a different mode to traditional
"Select and Edit mode" (mouse cursor is standard arrow pointer), it is still possible
to select objects (what is not possible in tracking modes, as you remember):
(a) Shift + Left button click selects an object (adds the object
to the list of selected objects) but does not clear other selections.
(b) Ctrl + Left button click selects an unselected object or unselects
an already selected object individually
from other selections.
Special symbols and context menus in grab mode
If you press down the left mouse button (which prepares for rotation) or the right
mouse button (prepares for shifting) but do not move the mouse position with button
down, an icon appears. The icon following a left mouse button click has a drop-down button right
beneath, which opens a special context menu for several movements and animations
that are only available in grab mode. (An info is given in the status
bar when you highlight a command in this context menu.)
With right mouse button, you have a symbol for a context menu. (The context menu
does not appear immediately, because Diamond expects you are initiating a shift
operation instead.) This gives you the chance to open
a context menu, if your right-clicking did not intend to start structure movement
but to have a context menu like in normal "Select and Edit" mode. This context menu is equivalent to the normal context menu
that is available in normal "Select and Edit" mode.
Using double-click
(a) Shift + Ctrl + Left button double click: A left button double
click in context with both Shift AND Control key pressed rotates the structure,
bringing the clicked point (atom, bond, or virtual point on the front hemisphere)
to the front, that means into the yz-plane or, if already lying in the yz-plane,
onto the +z-axis).
(b) Left button double click in context with Shift OR Control
key opens the dialog to edit the selected object(s) (like double-click
in Select & Edit mode).
(c) Left button double click without Control or Shift key: Centers
context-sensitively and dependent from position, enlarges, or adjusts.
-- Ganz aussen (mindestens 1 cm vom aeusseren Rand der Struktur entfernt) ->
"adjust". "Aussen" klicken (nicht im Zentrum des Zeichenfelds) -> "center here".
"Innen" klicken -> "enlarge here" (oder "decrease here", wenn Maximum erreicht).
Using the mouse wheel
(a) With Shift key or NO status key pressed: Changes the enlargement factor (i.e.
"zooms" in or out) but keeps the atom under the mouse cursor at its position. That
means the depiction of the center of rotation is shifted alongside with the change
of the enlargment factor in order to keep the moiety at the current mouse position.
(b) With Ctrl key pressed: Changes distance of camera/viewer from
center of rotation, that means increases or decreases the perspective impression.
(c) With Shift AND Ctrl key pressed: Performs "Walk in" or "Walk
out", rsp., that means moves camera/viewer position into the structure or out of
the structure.
Pressing down the mouse wheel (the "mouse wheel button") initiates the special mouse
wheel mode, which is described in details in the article "Using the mouse wheel".
(This is also available from normal "Select and Edit" mode.)
Terminate grab mode with Escape key
Pressing the Escape key terminates "Grab mode" and returns you to "Select and Edit"
mode, the mouse cursor changes from hand symbol back to default arrow pointer symbol.
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Next article: Neighbouring preview of atoms and molecules around the atom (molecule) under mouse cursor
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