## 3. Setting Tracer Display Attributes

The display attributes define how particle traces are displayed. They are grouped together in the attributes property:

• style 0 means display traces as lines, 1 means display them as rectangular tubes. In the latter case, the tube rotates in accordance with the velocity field's rotational, and shrinks and expands with the field's divergence.

• linewidth: Used when displaying traces in line-style.

• show_edge: Used when displaying traces as rectangular tubes. Outline the tube's edges. This makes the tube's rotation better visible.

• show_mesh: Used when displaying traces as rectangular tubes. Show the edges of all polygons of the tubes. This is seldom used.

Note When a particle trace is calculated, the number of points can reach 100000 or more for large models. When displaying traces as tubes, the number of polygons becomes too large to display efficiently. To make OpenGL performance acceptable, baspl++ omits those points which are less than about 10 degrees off from the line passing through the two previous (included) points (the actual criterion is more complex, as tube rotation and radius change are also considered). This results in a much lower number of points. Thus the mesh displayed does not contain all points passed by the tracing algorithm.
• show_solid: Used when displaying traces as rectangular tubes. Display traces as solid rectangular tubes. This is the default and especially effective if a LightSource has been added to the Scene object.

• scale: Used when displaying traces as rectangular tubes. This factor defines the relative thickness of the tube. baspl++ sets this factor such that it is in relation with the size of the complete model.

• radius_amplify: Used when displaying traces as rectangular tubes. This parameter defines the change in tube thickness and must be set manually for best effect.