# Cut plane: about

## Definition

A cut plane is a face support, on which the user can evaluate a spatial quantity.

## Use

A cut plane is used for:

- plotting of scalar spatial quantities as color-shading isovalues
- plotting of scalar spatial quantities as arrows

## Types of cut planes

A cut plane can be:

- a plane parallel to one of the planes XY, YZ or XZ
- a tilted plane passing through one of the axes X, Y or Z
- a plane defined by the equation Ax+By+Cz=D

## Cut plane and infinite box

The spatial support of the cut plane type cannot be extended beyond the bounded study domain. (A cutting plane stops at the border of the infinite box. It does not exceed the infinite box.)

## Mesh

The mesh of a cut plane is a surface mesh, which corresponds to the intersection of the cut plane with the volume elements that it cuts out.

## XY, XZ, YZ planes

A plane parallel to one of the planes XY, YZ or XZ is characterized by:

- a coordinate system
- an offset position with respect to a plane

An example of the XY plane is presented below.

## Tilted planes

A tilted plane passing through one of the axes X, Y or Z is characterized by:

- a coordinate system
- a rotation angle around an axis

An example of the plane defined by an offset angle about the X-axis is presented below.

## Plane defined by the equation Ax+By+Cz=D

A plane defined by the equation of the form Ax+By+Cz=D is characterized by:

- a coordinate system
- 4 coefficients of the equation

An example of the plane defined by the equation Ax+By+Cz=D with the coefficients of the equation different from 0 is presented below (the plane is rotated around two principal axes).