path
Paths are created using path or addpath command from points. Paths can be created using all the points or the selected set of points. Path consists of atleast 2 points. Once a path is created points used for creating the path are removed. A path can be modified after it has been created - points can be added, moved and removed from the path.
Paths can be employed for cropping and blending transfer functions. Volumes can be cropped along a given path. Thick slices can also be viewed along a given path.
Users can add, load and save path data via command dialog.
Keyboard and Mouse bindings for path.
Commands via path dialog
Left click on the path curve will add a point and right click on a point will remove the point. Left mouse drag will move the selected point. Middle mouse drag will move the entire path.
Users can undo/redo changes made to the paths.
Mouse grab for crop/dissect/blend/displace/networks/paths/clipplanes is switched off when project is first loaded and when playing keyframes. Toggle mouse grab with g or toggle via Toggle menu.
Viewport functionality adds a multiperspective camera. Viewing direction for the multiperspective camera is along the green axis. The up-vector for the camera is the red axis. Snapshot are taken along the path and are joined together to form a single cohesive image. Near and far cutting planes is controlled by the green axis length. Users can press spacebar while in viewport window to bring up the path dialog.
| Parameters | Description |
|---|---|
| Color | Path color. |
| Opacity | Path opacity. |
| Smoothness | Controls spline interpolation for intermediate points on the path. Value of 1 implies linear interpolation. |
| Sections | Controls the number of facets when path is rendered as tube. |
| Cap Style | When path path is shown as tube, end the path with flat face/round face/arrow. |
| Arrow Direction | When path has arrow style draw arrow forward/backward facing. |
| Arrows For All | Applicable only when cap style is arrow. |
| Arrow Length | Controls length of arrows - when cap style is arrow. |
| Display Angle | Show angle between first 3 points of the path. |
| Display Path Length | Show length of the path besides the path. |
| Text Color | Text color for path length. |
| Length Text Distance | Display length of the path at a distance in screen pixels away from path. -ve values will display path length on the opposite side. |
| Same For All | Set radii and angles to be the same for all points on the path. |
| Use For | Switch on crop/blend options. Paths can be used for cropping and blending operations. |
| Keep Inside | When using path to crop/blend, flip the direction of crop/blend operation. |
| Keep Ends | When using path to crop/blend, decide on what to do beyond the end of the path for crop/blend operation. |
| TFset | Choose transfer function set when applying blending option. |
| Interpolate | Interpolate this path between keyframes. Path points, radii and angle are interpolated only if the two paths at the keyframes have identical number of points. |
| Viewport | See below. |
| Viewport tfset | Create the straightened image with the transfer functions from the specified transfer function set. Value of -1 will switch off the texturing on the clip plane. |
| Viewport style | Show straightened image in horizontal/vertical fashion. Users can manipulate the path from within viewport only when viewport style is in horizontal mode. |
Viewport
Viewport functionality adds a multiperspective camera. Viewing direction for the multiperspective camera is along the green axis. The up-vector for the camera is the red axis. Snapshot are taken along the path and are joined together to form a single cohesive image. Transfer functions from the set specified by Viewport tfset are used to create the textured slices in the image. Near and far cutting planes is controlled by the green axis length.
Users can press spacebar while in viewport window to bring up the path dialog.
Viewport is specified by four parameters - x,y,wd and ht. x,y specify the lower left corner of the viewport; wd and ht specify the width and height of viewport. The x,y,wd and ht all are normalized values and should be between 0.0 and 1.0. This is done so that viewport scales with the size of rendering window.
Viewport is switched off by removing all the viewport parameters, or, by pressing DEL in the viewport.
Users can interact with a path from its viewport. Mouse and keypress commands can be issued to path via its viewport. Following is the mouse bindings and keystrokes that are recognized from viewport :
Mouse Bindings
| Mouse drag | When dragged horizontally path will be moved along the spine. When dragged vertically the path is moved along green axis. When one of the path points is green (i.e. selected) then only that point will be moved. The viewport will change accordingly. |
| Alt + Mouse drag | Rotate path about spine. |
| Shift + Middle Mouse drag | Change red axis length, which in turn changes the image height. When one of the path points is green, then red axis length for only that point will change. |
| Shift + Mouse wheel | Change green axis length, which in turn changes the slab thickness. When one of the path points is green, then red axis length for only that point will change. |
| Mouse wheel | Move path up/down along the red axis. |
*Keyboard Bindings*
| Space | Opens path dialog. |
| DEL | delete viewport - set viewport parameters to (-1,-1,-1) |