# The 3D view

The structure is drawn with PyVista and VTK. The **Display** panel contains the
settings of the drawing, one section for each kind of object in the view. The
sections open folded; a click on a title unfolds it. Objects that can be hidden
have a switch at the right of their title, which works with the section folded.

## Drawing options

- **Atoms** — radius, opacity, element labels (size and colour) and a colour for
  each element. Labels follow the background, black or white, unless a colour
  is chosen.
- **Bonds** — radius, colour, and the tolerance used to decide which atoms are
  bonded; hydrogen bonds, drawn as dashed D–H···A interactions, with their own
  colour and width.
- **Unit cell** — colour and width of the cell edges.
- **Coordination polyhedra** — opacity, minimum coordination and edge width, in
  the style used by VESTA.
- **Thermal ellipsoids** and **Phonon arrows** — available when the output
  provides them.
- **Measurements & symmetry** — the colours of the objects drawn by the
  Geometry and Point symmetry panels.
- **View** — background colour, projection (perspective or orthographic), the
  **a**/**b**/**c** axes and the orientation marker.

**Reset to defaults**, at the foot of the panel, restores every setting except
the background, which follows the light or dark appearance of the program.

Measurements made in the **Geometry** panel are drawn in the same view.

## Orientation

The **VIEW** group of the toolbar orients the structure along a lattice vector
and restores a view of the whole; the **ROTATE** group turns it by a fixed
step, which makes a given orientation reproducible.

Orthographic projection, selected in the Display panel, is appropriate for figures:
a direction parallel to an axis remains parallel to it.

## Large structures

Large cells remain interactive; the geometry is built once and updated in
place. The supercell below contains 8,100 atoms with coordination polyhedra
drawn.

![A 3x3x3 supercell with polyhedra, an elastic surface and the symmetry panel](screen3.png)

## Saving an image

**File → Export image…** writes the current view as PNG, JPEG, TIFF, SVG, PDF
or EPS, with a choice of resolution and a transparent background. The
Brillouin-zone window uses the same dialog.