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Gradient Editor

The Gradient Editor viewport lets you control Gradient textures in Modo. Gradients are useful in modifying values gradually across a certain parameter such as along a surface, based on its length or angle. Gradients can also be used to drive other layers for complex texturing. It's all dependent on the Layer Effects that are selected and the input parameters. For more information on Gradients, see Gradient.

Usage

A gradient layer is added to the Shader Tree using the Add Layer button under Processing > Gradient. Once created, you need to assign the appropriate effect for the target surface. For more information on working with Shader Tree layers, see the Shader Tree topic. With the gradient item selected, in the Properties panel, you next need to select the input parameter, controlling how the gradient modulates the surface it is applied to. By clicking the Edit Gradient button you can open the Gradient Editor viewport. The Gradient Editor is in many ways similar to the Graph Editor; the only difference being that the graph editor modifies values over time. It is helpful as well if you are familiar with the Color Picker Viewport as its use is integral for selecting color values.

Channels and Channel Visibility

From within the Channels section on the left side, you can select the appropriate value(s) you want to modulate. This is dependent on the desired effect; for diffuse color this would be the Color R, -G, and -B channels, for specular amount this would be the Value channel (any input that requires a single percent is a Value graph). Once selected, a line representing the numerical values of the channel appears in the graphing window for adding keys.

Along the right side of the viewport are some toggle buttons that control the visibility of the channels.

Key Creation and Selection

Keys can be added to the currently-selected curve(s) by middle-clicking either on the curve itself or anywhere on the background. Alternately, you can use the Ctrl+Alt+click to create a key. Key values are created at the location of the cursor. The Input and Value numeric fields in the upper-left corner allow for precise numerical editing of selected keys.

Selecting a key can be done by clicking with the cursor directly over the key itself. Holding the Shift key while selecting a key adds it to the selection. Holding the Ctrl key removes a key from the selection set. Clicking on the editor's background deselects all keys.

Clicking and dragging on the background starts a box marquis selection. Drag out the box to enclose the keys you want to select and release the mouse button. All keys within the box become selected. Any keys outside the box are deselected. Holding down the Shift key adds the keys within the box to the selection while the Ctrl key removes them.

Setting Colors for Keys

The color of selected keys can be set or adjusted by either clicking and dragging on the Color Picker viewport, or from within the right-click context menu. Selecting Key Color from this menu opens the Color Picker, from which a color may be chosen. In both cases, additional keys may be created on associated curves at the key Input value. Clicking the corner swatch for the color opens the system color picker.

Deleting Keys

Keys can be deleted from curves in two ways: to delete only the currently-selected keys, press the Delete key, to delete the currently-selected keys and keys at the same Input value on associated curves, select Delete Key from the right-click context menu.

Editing Keys

Clicking and dragging on a key selects the key, if it's not already selected, and allows quick editing of both Input and Output values at the same time. If there are several keys already selected and you click and drag on one of them, then all the selected keys are modified. Middle-clicking and dragging on a key works in a similar way except that editing is constrained to the Output value. Similarly, right-clicking and dragging constrains the edits just to the input parameter value.

Middle-clicking and dragging vertically on the background adjusts the Output value of all selected keys. Right-clicking and dragging horizontally on the background adjusts the Input value of all selected keys.

Ctrl+middle-click+drag on the background provides constrained editing of Input and Output values for selected keys, based on the initial direction of movement. Double-clicking on a key selects all the keys on the curve.

Context Menu

The Gradient Editor context menu is accessed by right-clicking. If the cursor is over an un-selected key when the menu is opened, the key is added to the selection. Operations performed from the context menu affect all the currently-selected keys.

Navigation

Panning and zooming behavior in the Gradient Editor is similar to that in the 3D Viewports, with a few additions:

• Alt+middle-click+drag adjusts the start value of the Input Range (horizontal), displayed in the editor, while Alt+right-click+drag adjusts the end value of the Input Range.

• Alt+Shift+middle-click zooms the Output Range, displayed in the editor, while Alt+Shift+right-click zooms the Input Range. In both cases, the zoom is centered on the initial cursor location.

• Alt+Ctrl+right-click provides box zooming.

• The mouse wheel zooms in and out around the cursor location.

Modifying Curves

The Gradient Editor also offers a lot of control over how values interpolate from one key to the next. This is represented by the curve/line that connects each key. By default, the values gradually fade from one to the next: this is the Auto setting. You can adjust the key settings so incoming and outgoing lines are smooth, linear, stepped, or a variety of other shapes. Small Bezier-like handles appear next to selected keys that allow you to make these adjustments. Clicking and dragging the handle modifies it, putting it in to the Manual mode. The handles relate to the key in two ways - there is the angle of the handle called Slope, and then the length of the handle called Weight. These two options combine to produce the final shape of the curve. Some buttons quickly set the most common Slope and Weight combinations.

The next group of buttons gives full control over both handles for each key: the incoming handle and the outgoing handle. You can think of the buttons representing the left side handle and the right side handle, where the setting is directed to each side, independent for the Slope and Weight. If the handle is unified, meaning adjusting one side moves the other in a straight line, then the outgoing settings are grayed out. The option gear in the middle allows you to "break" the handles or "unify" them, and to zero out the angle, which makes them perfectly horizontal again. There are a number of settings under the pop-up menu when clicking any of the buttons.

The Slope controls include:

• Manual - gives full control over Slope (handle angle).

• Auto - automatically adjusts Slope to produce a smooth ease-in and ease-out from the previous key value to the next.

• Linear In - angles the Incoming Slope to point toward the previous key, producing a straight line between keys.

• Linear Out - angles the Outgoing Slope to point toward the next key, producing a straight line between keys.

• Flat - sets the Slope to 0 degrees flat, regardless of the positions of the previous and next keys.

• Auto Flat - acts just like Auto except when the incoming or outgoing keys match the value, then it acts like Flat.

• Stepped - eliminates the Slope and Weight altogether, retaining the previous key value up until a new key is introduced.

The Weight control include:

• Manual - gives full control over Weight (handle length).

• Auto - automatically adjusts Weight to produce a smooth ease-in and ease-out from the previous key value to the next.

The following buttons also allow you to quickly break or unify the handles Slope and Weight in a single stroke.

Managing Keys

The Gradient Editor also offers some useful functions for working with key values. Working with a clipboard buffer, you can move keys around, and even move them from one channel to another. The Paste command simply adds the key values to the target, the Insert command adds them to the target and moves other keys as necessary, while Replace adds the keys, removing any existing keys it might overlap.

The following buttons open dialog boxes that allow for easy gang editing of multiple selected values.

Icons	Action
	Opens the Set Input Value dialog panel for adjusting the time position (not directly applicable to gradients). • Time - determines the position in time to move the selected keys to. • Absolute - when enabled, Absolute time is used, where a specific time can be defined; when disabled, the time is relative to the current time position. • Linked - when enabled Linked keys (such as those of the R, G, and B channels) remain linked in the same relative position, even if only a single channel is edited; when disabled, keys can be moved freely. • Ripple - when enabled, all the following values of those selected are shifted by the same amount.
	Opens the Set Key Value dialog panel for adjusting the value of the selected keys. • Value - defines the new value that is applied to the selected keys when the mode is set as Set; defines what value is added when mode is set to Add. • Multiple by - acts as a multiplier of the selected values when mode is set to Multiply. • Mode - determines how the values affect the selected keys: Set, Add, and Multiply.
	Opens the Scale Keys dialog panel for scaling the value of the selected keys. • Scale - defines the amount of scaling applied to the selected keys. • Center Options - determines the center location to scale the keys from- Start, Center, End, Time, and User. When Time or User is selected, the Center Value can be used to define the specific center. • Center Value - determines the specific center locations when the Time or User options are selected as the Center Option. • Mode - two modes to determine which direction gets scaled: Input scales the interval (horizontal) while Output scales the value (vertical). • Link - when enabled, linked keys (such as those of the R, G, and B channels) remain linked in the same relative position, even if only a single channel is edited; when disabled, keys can be moved freely.
	Opens the Key Invert dialog panel for adjusting the value of the selected keys. • Mode - two modes to determine which direction gets inverted: Input inverts along the interval (horizontal) while Output inverts along the value (vertical). • Local - when the Local option is enabled, the inversion happens individually for each channel; when disabled, the inversion happens as a group for all that is selected.

Behaviors

The Behavior buttons define the incoming and outgoing curves that are outside the area of defined keys. The left button defines the per-behavior and the right button the post-behavior.

• Constant - values remain the same. With the Auto Slope and Weight options, ease-in or out as it transitions to the key values.

• Stop - values remain the same. For Auto Slope and Weight, transitions to the key values act as if linear - a sudden transition.

• Linear - values project outward in a linear fashion from the first or last key, providing a constant offset.

• Repeat - values of keys are repeated. When incoming and outgoing values match, a loop can be created.

• Oscillate - values are repeated forwards, and then reversed, like a ping-pong type effect.

• Offset Repeat - values of keys are repeated, but each subsequent repeat is offset by the amount of the last key.

• Reset - values are set to flat 0 (zero) outside the key area.