streamlines

Synopsis

integrate a velocity field producing streamlines or streamribbons

Input Port

in_field	Mesh + Node_Data
in_probe	Mesh of initial streamline positions
ui_parent	user interface parent object

Parameters

velocity vector	UIradioBoxLabel	which vector component to streamline
Direction	UIradioBoxLabel	forward/backward motion of particles
nsegments	UIslider	accuracy of integration
max segments	UIslider	number of integration steps
order	UIslider	order of integration
min_velocity	UIslider	minimum velocity value when integration stops
Ribbons	UItoggle	create streamribbons
ribbon width	UIslider	control width of ribbon
ribbon angle	UIslider	set ribbon angle

Output Port

out_fld	Mesh + Node_Data
out_obj	output renderable object

Description

streamlines generates streamlines or streamribbons based on a field of any mesh type that has at least one component that is a one-, two-, or three-element vector.

You place a sample of points (the in_probe) at a starting location in the field. Then, for every time step, streamlines advances each sample point through space based on the interpolated value of the vector field at its present position. The result is a set of streamlines or streamribbons showing the progress of massless particles through a vector field.

streamlines is similar to the advector macro, except that the result is a set of lines instead of a dynamically updated set of glyphs.

Input

in_field

The input field can have any type of mesh. Its Node_Data must contain at least one component that is a one-, two-, or three-element velocity vector.

in_probe

Any mesh whose coordinates represent the sample points. To create this sampling mesh you can use the plane objects in Geometries or the slice macro.

ui_parent

A port to connect to a user interface object that contains the macro's widgets. By default, it is connected to the default user interface object in the application in which the macro is instanced. (This default connection is not drawn.)

Parameters

velocity vector

UIradioBoxLabel. Radio buttons to pick on which component to base the streamlines. The selection must be a three-element vector.

Direction

UIradioBoxLabel. Radio buttons to pick the direction of streamline generation, forward or backward. The default is forward.

nsegments

UIslider. An integer slider that sets how many integration steps will be used within one grid "cell" to compute the streamline path. The default is 2. The range is from 0 to 16.

max segments

UIslider. An integer slider that sets the total number of integration steps. When an individual streamline exceeds this value, integration for it stops. The range is from 1 to 10000. The default is 256.

order

UIslider. An integer slider that sets the order of integration. Higher orders are more accurate, but execute more slowly. The default is 2. The range is from 1 to 4.

min_velocity

UIslider. A float slider. When a streamline falls below this velocity, the integration process for that streamline stops. The default is 0.00001. The range is from 0.0 to unbounded. You can use this to prevent wasted computation for streamlines barely moving, or even stationary (min_velocity = 0).

Ribbons

UItoggle. When on, streamlines produce streamribbons rather than streamlines. The default is off.

ribbon width

UIslider. An integer slider. Scales the width of the ribbon. Ribbon width varies along its length according to the divergence of the flow. This value controls ribbon width at the beginning of the ribbon. The default is 1. The range is unbounded.

ribbon angle

UIslider. An integer slider. Controls the initial angle at which the ribbon is drawn. The default is 0. The range is 0.0 to 360.0.

Output Port

out_fld

The output field is a new unstructured mesh of cell type Polyline that represents the streamlines. Its new Node_Data contains the selected element's velocity component. The output also contains a reference to the input field's xform.

out_obj

This is a renderable version of the output field.

Algorithm

The streamlines are calculated using the Runge-Kutta method of specified order with adaptive time steps.

Example

Libraries.Examples.Visualization.Stream
v/dv_examp/stream.v

File

v/modules.v

See also related modules

Not applicable.