VIEW OPTIONS HIDDEN Algorithm

  

This command enables the user to select algorithms for use in the calculation of hidden views. The style of hidden view is selected via the VIEW HIDDEN command.

There is an extra option in FEMGEN to allow the user to selectively fill the mesh of hidden views with background rather than colour. After the option MESHFILL OFF has been set, if the picture is recalculated, all of the mesh to be displayed will be filled in the background colour, while any geometry will still be filled with colour or shaded.

The command VIEW OPTIONS HIDDEN BEAMS enables the user to control the display of beam elements in hidden views by ignoring them altogether or to control how they are represented.

Algorithm Control Comments

QUICK A quick algorithm based on a single pass of the data is used. This is the default and will usually produce correct pictures (See note 1).

RIGOROUS A more rigorous algorithm based on a multiple pass on the data is used. The time taken is longer than for the QUICK algorithm (See note 1).

MESHFILL [OFF] An option to specify whether the mesh is filled with colour or background when displaying a view hidden picture (See note 2).

BEAMS QUICK ['real'] A simple representation of beams will be included in hidden views, where 'real' is used to increase or decrease the apparent width of the beam. See notes 3 & 4.

PHYSICAL ['real'] FEMGEN only. A realistic representation of beams based on beam type and dimensions will be included in hidden views, where 'real' is used to increase or decrease the apparent width of the beam. See notes 3 & 5.

OFF Beams will not be included in hidden views.

Notes:

1.

Limitations on the QUICK and RIGOROUS algorithms
The QUICK algorithm will sometimes produce an incorrect picture where there is a large difference in the relative size of elements in the model. In this case the RIGOROUS algorithm should be used. Neither algorithm will correctly handle non finite element data in which elements penetrate one another or in which element A overlaps element B, which overlaps element C, which overlaps element A.

2.

Filling the mesh
The MESHFILL [OFF] command is available only in FEMGEN . While MESHFILL is set to OFF, any VIEW HIDDEN SHADE or VIEW HIDDEN FILL COLOUR pictures of meshes will look like VIEW HIDDEN FILL pictures. This command has no effect on any geometry being displayed. It is useful for composing pictures with part of the model (the mesh) drawn in VIEW HIDDEN FILL and the rest (the geometry) in VIEW HIDDEN SHADE. This command only affects the colour used to fill the inside of the element. The edges will still be drawn in the assigned colours. The default is to have MESHFILL on, and so fill the mesh in any colours currently allocated when the commands VIEW HIDDEN FILL COLOUR or VIEW HIDDEN SHADE are issued. The command VIEW OPTIONS HIDDEN MESHFILL will reset to the default setting of MESHFILL on.

3.

Beams in hidden views
The command VIEW OPTIONS HIDDEN BEAMS allows the user to tailor the presentation of beams in hidden views. If beam elements are not required at all, some execution time can be saved by the command VIEW OPTIONS HIDDEN BEAMS OFF. Beams can be switched on again by the QUICK or PHYSICAL options.

4.

Simple beam visualisation
When VIEW OPTIONS HIDDEN BEAMS QUICKis used, a beam is generally thickened into a rectangle where length to width is 40:1 The exception is that on 3D displays, for the command VIEW HIDDEN FILL or VIEW HIDDEN SHADE, beams are converted to an elongated brick with 6 faces. (HE8). In every picture, the fattening factor is set for the first beam processed and used for every subsequent beam. The command VIEW OPTIONS HIDDEN BEAMS QUICK 'real' allows the user to apply an extra fattening factor, and so make the beams appear fatter or thinner.

5.

Realistic beam visualisation
When VIEW OPTIONS HIDDEN BEAMS PHYSICAL is used, a realistic representation of each beam element is drawn. Currently the standard section types available in the FEMGEN neutral environment (box, general, pipe, t-section and u-section) are displayed. Each type of beam is dislayed using the dimensions defined with the BOX,PIPE,GENERAL,TSEC or USECoptions in PROPERTY PHYSCAL and attached to the underlying geometry with PROPERTY ATTACH. Consequently a visual check of the beam section type, dimensions, orientation and offset is provided. For beam properties defined with PROPERTY PHYSICAL GENERAL an equivalent cylinder is calculated and used for the visualisation.

For beam section types not included above, the locations of beams can be checked with VIEW OPTIONS HIDDEN BEAMS QUICK.

When an offset is specified the distance from the beam axis to half the section depth is used for the positioning of the beam section.

A general warning is given when beam elements without physical properties are encountered.

VIEW OPTIONS HIDDEN SHRINK and VIEW OPTIONS HIDDEN SHRINK GEOMETRY may be useful when viewing the beam sections.

Examples:

1.

VIEW OPTIONS HIDDEN RIGOROUS

Select the rigorous algorithm for hidden views.

2.

VIEW OPTIONS HIDDEN MESHFILL OFF

Fill any mesh to be displayed with the background colour.

3.

VIEW OPTIONS HIDDEN BEAMS OFF

Ignore any beam elements in the model when producing a hidden view.

4.

VIEW OPTIONS HIDDEN BEAMS QUICK 2.0

Process the beam elements and make them appear twice as wide as the default when producing a hidden view.

5.

VIEW OPTIONS HIDDEN BEAMS PHYSICAL

When producing a hidden view show beam elements with a realistic cross section and with the actual dimensions used in the beam property definition.

See also the following commands

'VIEW HIDDEN'