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Clip Planes
Clip planes (not to be confused with the planes used in the clipping volume defining the projection) cut away the portion of the model on one side of the plane. These Figuresshow the use of 2 clip planes. Six planes are available in Moritz to clip the model from above and below in each of the X, Y, and Z directions. For each direction, there is a + and - plane. The +X clip plane, for example, eliminates elements of the model with X coordinate greater than the plane value.
Initially, the clip planes are undefined and disabled. When a model is imported, the clip planes are defined (but not enabled) at the geometry center. The planes are defined (or changed) by setting their value in one of the 2D windows. The 3D Clip Planes items in the Graphics and 2D context menus contain items for dragging the planes. Once one of these items is selected, moving the cursor in a 2D window with the left button held down moves the corresponding clip plane. If the <ctrl> key is held down while dragging the clip plane, the 3D display is not updated until the key or mouse button is released. Once a plane has been defined, it can be enabled or disabled. The Clip Plane submenus (there is also one in the 3D context menu) contain entries for changing the enabled/disabled state of each plane and a Disable All item.
The clip planes are an OpenGL feature. If the Solid Clip mode is on, Moritz introduces a plane just above or below a clip plane and repolygonalizes the cells so that the cells appear solid at the clip plane rather than having their interiors revealed. These Figuresshow a model with and without solid clipping. Regardless of the solid mode setting, the interiors are shown as the clip plane is being dragged with the mouse. Because adding the solid face involves characterizing all cells, there may be a noticeable delay for complicated models. The repolygonalization is not successful for all cells. It works best with simple cells composed of planes. For others, the interior is not hidden.
Specifying clip planes in a file (with the CP command) containing the geometry information can cause trouble if the solid clip mode is on. The cell bounding boxes are determined when they are initially polygonalized. If the cell description contains the solid clip plane at that point, the bounding boxes of affected cells will be incorrect and they will not appear or appear incorrectly in the 2D plots; the 3D image can be screwed up as well. To prevent this trouble, a command file (.sab) should be read as a checkpoint file. If it is read as a sabrina file, or if the CP command is an embedded comment in an MCNP file, a CT command (CheckpoinT) should appear before the CP command(s).
 White Rock Science http://www.whiterockscience.com/wrs.html 505 672 1105 |
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