Some of the additional capabilities of the transfer function editor include:
- Multi select: You can select multiple control points using ctrl-left click (command-left click on Mac) or shift-left click. Then all of the selected control points can be dragged together.
- Binding color and opacity control points. If one color control point and one opacity control point are selected, you can click the buttons "Bind Color->Opacity" or "Bind Opacity->Color". When opacity is bound to color, the selected opacity control point will move to the same position on the x-axis as the selected color control point. The opposite occurs when color is bound to opacity.
- Histogram scaling choices: Click on the left mouse button in the editor window, and choose either "Boolean", "Linear", or "Log" scaling of the histogram. The boolean scaling is useful to identify where any data points are. The log scaling provides enables both large and small histogram values to be seen together.
- Multiple opacity widgets: By default the opacity is determined by a single function, defined by interpolating a set of opacity control points. Additional opacity widgets can be created using the right-mouse menu in the editor window. When you create a new opacity widget, you have the choice of creating one based on "Control Points" (as above) or using a "Gaussian" or "Inverted Gaussian" curve. A Gaussian or inverted Gaussian curve can be edited by selecting it and then dragging the red and blue control points associated with it.
- To remove an opacity widget, select it by clicking on its opacity curve with the right mouse button, then select "Delete Widget".
- When multiple widgets are defined, the full opacity function is either the sum or the product of the opacity functions. To control the combined effect of multiple opacity widgets, select the opacity curve of a widget with the right mouse button, and choose Opacity Composition to be either "Addition" or "Multiplication".
- Controlling the display of mouse coordinates in the transfer function window: On some systems the display of mouse coordinates in the transfer function editor may interfere with interactive editing. This can be disabled by un-checking "Track Mouse Position in Transfer Function Editors" in the User Preferences Panel.
