Curve Editor

Two-dimensional curves are used for many purposes in Realsoft 3D: as a VSL shading object, for controlling animations etc. Consequently, The Curve Editor documented below can be encountered in many areas of the user interface.

The curve editor can be used in a default state where the 1-4 transformation curves are visible. A curve object consisting of one sub curve is suitable for transforming time, whereas a three-component curve can be used for rgb transformations. The sub curves are colored as 1.=red, 2.=green, 3.=blue, 4.=black.

The Curve Editor in the default state

The Gradient state of the curve editor shows a curve-transformed rgb gradient on the background of the editor. This is especially convenient when designing color gradients for materials or when viewing animated color attributes. It is much more intuitive to see the actual color than three curves representing numeric rgb components.

The curve editor has only a few controls: the actual graphical area showing the curves, and two floating value gadgets for accurate control of selected curve points.

The Curve Editor in the gradient state

Mouse Navigation

The following mouse operations are available for quick navigation:

Point Editing

Adding points: You can easily add a point to a curve by clicking the curve. A new point is inserted to all visible curves that were hit and which did not have a point at the clicked position.

Deleting points: Select the points and hit Del key or select 'Delete' from the popup menu.

Moving points: Select the points. Then press the left mouse button down on top of a point and move the mouse holding the left button down. Release the left mouse button to finish moving. You can cancel the move operation with the 'Esc' key. It cancels the operation, but it does not undo already moved points.

Point Selection

The point selection rules are similar as in object or 3D handle selection. You can select points by clicking or dragging with the left mouse button. Key modifiers add useful selection functionality. Without a modifier, a selection operation always clears the previous selection. Clicking or dragging empty area deselects all points.

The summary of point selection operations is shown below:

The Popup Menu

Delete Points: Deletes the selected points. Note that a valid curve has always at least two points. The delete tool does not allow point reduction below this minimal amount.

Create Predefined Curve: Initializes an empty curve to a simple default shape. This operation is available for example in animation curve editing where new animated attributes may not have any curve initially defined. The following alternatives are available:

Type: Selects the type of the curves from the following alternatives:

Extrapolation: Defines the result of curve evaluation outside the range of curve points.

  • Flat: The default choice. The value of the first point is applied for parameters before the curve starts. For parameters after the curve end, the result is defined by the last point's value.
  • Linear: Curve is extended linearly to the tangent directions at end points.
  • Repeat: The curve shape is repeated in a cyclic manner.
From top to down: Flat, Linear and Repeating extrapolation

Fit View to Curve: Resets the curve editor after zoom and pan operations so that the current editing range (see 'Set Minimum and Maximum Values' below) matches exactly the window size.

Simplify: Removes unnecessary points of the curves i.e. reduces the point count without changing the curve shape.

Align: Changes the y values of the points between the first and the last selected point of each visible curve so that the points match a straight line.

Set Minimum and Maximum Values: Opens a window for controlling the parameter and output range of the curves. The curve editor allows editing within a certain numeric range. You can define the range using this window.

The scaling dialog has the following options:

  • Rescale Curve: If set, the curves are scaled to match the change in editing range.
  • Apply: Sets the new scale. The scaling window is left open.
  • OK: Sets the new scale and closes the scaling window.
  • OK: Closes the scaling window without changing the scale.

Red, Green, Blue, Black Curve: These menus control visibility of the component curves. When editing complex curves, it may be necessary to hide all but one curve. The hidden curves do not interfere with editing actions.

Show All Curves: Makes all component curves visible.