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McStas: Shape

[ Identification | Description | Input parameters | Links ]

The Shape Component

A geometric shape without effect on neutron, for instrument display purpose.


  • Site:
  • Author: E. Farhi
  • Origin: ILL
  • Date: June 23rd 2009


An inactive geometrical shape, for drawing purposes only.
It does not propagate neutron, nor interact.
Geometric shape may be a cylinder, a sphere, a box or any other shape
box/plate:       xwidth x yheight x zdepth (thickness=0)
hollow box/plate:xwidth x yheight x zdepth and thickness>0
cylinder:        radius x yheight (thickness=0)
hollow cylinder: radius x yheight and thickness>0
sphere:          radius (yheight=0 thickness=0)
hollow sphere:   radius and thickness>0 (yheight=0)
any shape:       geometry=OFF file

The complex geometry option handles any closed non-convex polyhedra.
It computes the intersection points of the neutron ray with the object
transparently, so that it can be used like a regular sample object.
It supports the OFF and NOFF file format but not COFF (colored faces).
Such files may be generated from XYZ data using qhull/powercrust, and
viewed with geomview
The default size of the object depends of the OFF file data, but its
bounding box may be resized using xwidth,yheight and zdepth.

Example: Shape(radius=0.05, yheight=0.1)

Input parameters

Parameters in boldface are required; the others are optional.
geometrystrName of an Object File Format (OFF) file for complex geometry. The OFF file may be generated from XYZ coordinates using qhull/powercrust0
radiusmOuter radius of sample in (x,z) plane0
xwidthmHoriz. dimension of sample (bounding box if off file), as a width0
yheightmVert. dimension of sample (bounding box if off file), as a height. A sphere shape is used when 0 and radius is set0
zdepthmDepth of sample (bounding box if off file)0
thicknessmThickness of hollow sample0
center1Flag to determine if OFF object is centered on its centre of mass.1


  • Source code for Shape.comp.
  • Geomview and Object File Format (OFF)
  • Powercrust/qhull

[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43

Last Modified: Tuesday, 16-Apr-2024 20:05:22 CEST
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