6.5 Control Widgets

SCIRun supports powerful display widgets. Examples of widget capabilities include managing cutting surfaces colored according to the local data values, displaying streamlines in vector fields, or selecting sub-volumes within the display area for further manipulation.

SCI has made interaction with widgets as consistent as possible. For example, controlling parameters is usually done by clicking and dragging on a cylindrical ``collar'' or a sphere element of the widget. Note that a single widget can have more than one purpose depending on the context in which it exists. The Rake widget, for example, selects a clipping or display plane through a three-dimensional object, and sets the seed points for a streamline module.

This section describes the widgets available within SCIRun and BioPSE.

6.5.1 Point Widget

Figure 6.4: The point widget for probing fields

 

6.5.1.0.1 Appearance

The Point widget consists of a sphere (see Figure 6.4).

6.5.1.0.2 Purpose

The primary purpose of the Point Widget is to select and retrieve information about a point, for example when probing a field.

6.5.1.0.3 Controls

Clicking and dragging the sphere moves the point widget to a new location.

6.5.2 Rake Widget

Figure 6.5: The rake widget for setting location and density of seed points

 

6.5.2.0.1 Appearance

The Rake Widget has an orientation, length, and value (see Figure 6.5). It consists of two spheres (A) connected by a cylinder (B) with a small slider collar (C) on the cylinder. There are also small resize cylinders (D) extending from the spheres.

6.5.2.0.2 Purpose

The primary use of the Rake Widget is to set the location and density of streamlines emerging from the long cylinder. It can also be used as a more general purpose three-dimensional slider, or a source for a stream surface.

6.5.2.0.3 Controls

Clicking and dragging either sphere changes the widget's orientation. Dragging either of the resize cylinders causes the size of the widget to change, and dragging any point on the main cylinder moves the whole widget without any change in orientation. Dragging the slider collar changes the associated value, typically the density of seed points for a streamline source.

6.5.3 Frame Widget

Figure 6.6: The Frame Widget

 

6.5.3.1 Appearance

The Frame Widget (see Figure 6.6) consists of four cylinders connected in a rectangle. In the middle of each cylinder there is a sphere (B), from which a resize cylinder extends (C).

6.5.3.2 Purpose

The Frame Widget is primarily used for image plane definition, defining stream volumes, and as a "tie dye'' similar to the Ring Widget described in Ring Widget.

6.5.3.3 Controls

Dragging a sphere rotates the widget about its center. Dragging on a resize cylinder extends or contracts the rectangle. Dragging any cylinder drags the entire widget through space.

6.5.4 Box Widget

Figure 6.7: The boxwidget for selecting sub-volumes

 

6.5.4.1 Appearance

The Box Widget (see Figure 6.5.4) consists of twelve connected cylinders (A) to form a hexahedral box (B) (three-dimensional rectangle). In the middle of each face of the box is a sphere with a protruding cylinder (C) providing resize control.

6.5.4.2 Purpose

The Box Widget is primarily used to select a subvolume of the workspace for further manipulation (e.g., volume rendering, isosurfaces, streamlines, mesh adaption) where the faces of the widget act as orthogonal clipping planes.

6.5.4.3 Controls

Clicking on and dragging a sphere rotates the widget about its center without changing the position of the center. Clicking on and dragging any resize handle causes the associated face to extend without changing its orientation. Dragging a cylinder causes the entire widget to move without changing its orientation.

6.5.5 Ring Widget

Figure 6.8: The ring widget for selecting cutting/projection planes

 

6.5.5.1 Appearance

The Ring Widget (see Figure 6.5.5) consists of a ring (A) with four embedded spheres (B), each with a resize cylinder attached (D). Between two of the spheres is a sliding collar (C). One of the resize cylinders has a special material property (typically a different color from the other cylinders) to indicate that it is the ``halfway point'' for the slider (E).

6.5.5.2 Purpose

The Ring Widget is primarily used to set the density of streamlines emerging from the ring. The ring serves as a set of seed points from which streamlines emerge. The Ring Widget can serve as a three-dimensional angle gauge, as a source for multiple streamlines throughout its surface, as a source for a stream surface from the outer ring, and as a source for a stream volume. The Ring Widget can also be used as a color sheet, or ``tie dye'', in which the surface is colored as a function of the scalar value of the field at each point.

6.5.5.3 Controls

Clicking and dragging the slider collar along the ring changes the density of the seed points or some other related parameter. Dragging the spheres controls the orientation of the Ring Widget, while moving the resize cylinders change the radius of the Ring Widget about its center. Dragging any other point on the ring moves the ring in space without changing its radius or orientation.