Shapes: Wire frame

A wire frame shape has no physical effect on the model, and is used solely for drawing purposes.

Wire frame shapes have the following data:

Orientation

This consists of three rotation angles, rotation 1, 2 and 3, defining the shape's orientation, $\Sxyz$, relative to the connection axes, $\Cxyz$. $\Sxyz$ is calculated by first aligning the shape with $\Cxyz$, such that $\Sxyz = \Cxyz$. Rotation 1 is applied about $\vec{S}_x (=\vec{C}_x)$, followed by rotation 2 about the new $\vec{S}_y$ direction, and finally rotation 3 about the new (and final) $\vec{S}_z$ direction.

Wire frame

The drawing data, represented by a set of vertices and either edges or panels, are used to draw the shape in both wire frame and, by default, shaded views (more elaborate imported 3D models may also be used).

The wire frame origin is defined relative to the shape axes $\Sxyz$, and the vertices are in turn defined by giving their coordinates relative to the wire frame origin. Wire frame symmetry can be one of none, xz plane, yz plane or xz and yz planes. If wire frame symmetry is specified then the vertices, edges and panels are reflected in the specified symmetry plane or planes to generate additional vertices, edges and panels that are implied by the symmetry.

The wire frame type determines whether the wire frame is specified by edges or panels. When specified by edges, the edges are defined by pairs of vertices, referred to by index. When specified by panels, each panel is defined by four vertex indices. When the vertex indices are distinct, a quadrilateral panels is defined. Triangular panels can be defined by duplicating one of the vertex indices.

Wire frame data can be imported from panel mesh files.

Wire frame

In the wire frame view, the pen data are used to draw the given set of edges or panels. When specified by edges, the edge diameter values are ignored in this case.

Shaded drawing

In shaded graphics view, only the pen colour is used. The pen thickness and style are not used.

If the wire frame is specified by panels, then these panels are drawn. Any quadrilateral panels are split into two triangular panels.

When the wire frame is specified by edges, the appearance depends on the edge diameter. If the edge diameter is ~ then that edge will be used to build a convex shape. If the edge diameter is given a numerical value, then that edge is drawn as a cylinder with the given diameter. Note that you can use a mixture of edge diameters (some defined, some set to '~') to combine both filled-in and framework shapes.