Brep Slicer Configuration Quick Help


Configure Slicer
The Configure Slicer dialog with default parameters.

These settings are used to configure the shape and dimensions of the slicing shape in a Brep Slicer object. The slicer can take the form of a plane, box, cylinder, or sphere. When the slicer is a plane, some additional options are available.

The Dimensions parameters change meaning based on the slicer type. For example the first dimension will be the Length of a Plane slicer, but the Radius for a Sphere slicer. However, the actual value stored in the first dimension will carry over when the slicer type is changed.

The slicer configuration settings are covered in detail below:

  1. Plane
  2. Box
  3. Cylinder
  4. Sphere
  5. Split Only (Plane Only)
  6. Use Infinite Plane (Plane Only)

Plane Slicer

Plane Slicer 1
A Plane slicer applied to a goblet-like surface of revolution, with Slicing disabled.
Plane Slicer 2
The same goblet with the Plane slicer active.

Uses a plane shape to slice the base objects. By default the plane is dimensioned automatically via the Use Infinite Plane option, but it can be dimensioned manually by disabling this option and adjusting the Length and Width by hand or via the Fit alignment option. The plane can be used to do the standard boolean slice, or it can be used imprint edges via the Split Only option.

Plane Slicer 3
The sliced goblet viewed from a different angle, showing the sliced faces.

When positioning the plane, the slicer's transformation gizmo's local z-axis corresponds to the normal of slicing plane. Thus translating along this axis, or rotating the slicer, are the primary ways to orient the plane. Translating along the local y and z axes has no effect when Use Infinite Plane is active, and only serve to help position the plane boundaries otherwise. The geometric center of the plane corresponds to the origin of the gizmo.

When positioning a slicing plane, it may be useful to temporarily turn off backface culling on the Brep Slice object (via the Display command panel), as the plane is not a solid, and thus will be invisible from one side while this option is enabled. However, for rendering purposes it is recommended to turn backface culling back on to prevent the slicer faces from 'clashing' with the sliced faces on the result object (i.e., causing the shimmering graphics artifacts due to z-buffer clashing). Click here for more information on controlling the visual appearance of the Brep Slice object.

Plane Slicer Missed a Block
A Plane slicer applied to a collection of simple solids. The block at the very bottom does not intersect the plane, so it is not sliced away even though it is 'below' the plane.

Note that even with the Use Infinite Plane option enabled, base objects that are completely 'below' the slicing plane will not be affected. They must intersect the plane to be sliced. This can lead to counter-intuitive results when slicing collections of objects. An object that is mostly below the slicing plane may be mostly subtracted by the plane, but when moved completely below the plane will no longer be sliced at all. In situations where this becomes a problem, it is recommended to switch to a Box Slicer with the same Length, Width, and Orientation, and adjust the Height until the desired result is achieved.

Box Slicer

Box Slicer
A Box slicer applied to the goblet.

Uses a solid box shape to slice the base objects. The Length, Width, and Height of the box can be adjusted.

When positioning the box, the local z-axis corresponds to the normal of the base plane of the box. The box grows along this normal as the Height parameter is increased. Increasing the Length and Width of the box make it scale along the local x/y axes. The center of the base plane of the box corresponds to the local origin of the gizmo.

Cylinder Slicer

Cylinder Slicer
A tilted Cylinder slicer applied to the goblet.

Uses a solid cylinder shape to slice the base objects. The Radius and Height of the cylinder can be adjusted.

The local transform gizmo is aligned to the cylinder in much the same way as it is for the box. Its origin is at the center of the base disk of the cylinder, and its z-axis is aligned to the normal of the plane the base disk is in. The Height parameters thus have identical behaviors. The Radius parameter scales the cylinder along all directions in the local xy plane.

Sphere Slicer

Sphere Slicer
A Sphere slicer applied to the goblet.

Uses a solid sphere shape to slice the base objects. The Radius of the sphere can be adjusted.

The way in which the local gizmo is aligned to the sphere may seem counter-intuitive at first. The sphere alignment is intended to mirror the plane alignment. Specifically, the local gizmo is aligned to the sphere in such a way that a sphere with an infinite radius would theoretically behave the same way as an infinite plane. The local z-axis points towards the center of the sphere, and the local origin is on a point on the sphere's surface. Thus the sphere grows 'outward' out of the local origin 'along' the local z-axis as the Radius parameter is increased.

Plane Slicer Options: Split Plane

Split Plane Option
The goblet sliced by a plane with the "Split Plane" option enabled.

Prevents the plane from removing any faces. It only creates sliced edges on the result where the plane intersects the base operands (this is like the Imprinting option on the Boolean tool).

This option can be used in conjunction with the Show Cut Edges option to highlight the cross-section edges of the base operands, without removing any of the base geometry.

Plane Slicer Options: Use Infinite Plane

This does not actually make the plane infinite, but makes the plane effectively infinite in the following sense: the plane will automatically dimension itself such that it is at least big enough to slice completely through all the base objects. This option is on by default, and must be disabled if the user wishes to manually dimension the plane.

This option can be confusing at first because when the slicing shape or the base shapes are moved around, the plane will change size. For example, if there are two base shapes, and they are moved farther apart, the plane needs to cover more space to be sure that it will slice completely through both. Similarly, since the plane is centered on its local gizmo, if this gizmo is moved, the plane may have to grow or shrink to make sure it can 'reach' the base shapes.

Document last updated: April 2010 (nPower version 7.0). Tested with Firefox 3.6.3, Internet Explorer 7.0.6002.