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### 6.3. Gradient Tool

This tool fills the selected area with a gradient blend of the foreground and background colors by default, but there are many options. To make a blend, drag the cursor in the direction you want the gradient to go, and release the mouse button when you feel you have the right position and size of your blend. The softness of the blend depends on how far you drag the cursor. The shorter the drag distance, the sharper it will be.

There are an astonishing number of things you can do with this tool, and the possibilities may seem a bit overwhelming at first. The two most important options you have are the Gradient and the Shape. Clicking the Gradient button in the tool options brings up a Gradient Select window, allowing you to choose from among a variety of gradients supplied with Gimp; you can also construct and save custom gradients.

If the gradient appears in black-and-white, then it will actually use the foreground and background colors instead (and you will see it colored that way in the tool options area). If it appears in color, then it will be used as is.

For Shape, there are 11 options: Linear, Bilinear, Radial, Square, Conical (symmetric), Conical (asymmetric), Shapeburst (angular), Shapeburst (spherical), Shapeburst (dimpled), Spiral (clockwise), and Spiral (counterclockwise); these are described in detail below. The Shapeburst options are the most interesting: they cause the gradient to follow the shape of the selection boundary, no matter how twisty it is. Unlike the other shapes, Shapeburst gradients are not affected by the length or direction of the line you draw: for them as well as every other type of gradient you are required to click inside the selection and move the mouse, but a Shapeburst appears the same no matter where you click or how you move.

| Tip
Check out the Difference option in the Mode menu, where doing the same thing (even with full opacity) will result in fantastic swirling patterns, changing and adding every time you drag the cursor.

#### Activate Tool

- The Blend Tool can be called in the following order, from the image-menu: Tools/ Paint Tools/ Blend.

- The Tool can also be called by clicking the tool icon:

#### Key modifiers (Defaults)

Shortcut

  The L key will change the active tool to Gradient Fill.

Ctrl , Ctrl ,

  Ctrl is used to create straight lines that are constrained to 15 degree absolute angles.

#### Options

Overview

  The available tool options can be accessed by double clicking the Gradient Tool icon.

Opacity

  The Opacity slider sets the transparency level for the gradient. A higher opacity setting results in a more opaque fill and a lower setting results in a more transparent fill.

Mode

  The Mode dropdown list provides a selection of paint application modes. A list of these modes can be found in the Glossary.

Gradient

  A variety of gradient patterns can be selected from the drop-down list. The tool causes a shading pattern that transitions from foreground to background color, in the direction the user determines by drawing a line in the image. For the purposes of drawing the gradient, the Reverse checkbox switches foreground and background.

Offset

  The Offset Value is the "slope" of the gradient.

Shape

  The Gimp provides 11 shapes, which can be selected from the drop-down list. Details on each of the shapes are given below.

  Linear

    The Lineargradient begins with the foreground color at the starting point of the drawn line and transitions linearly to the background color at the ending point.

  Bi-Linear

    The Bi-Linear shape proceeds in both directions from the starting point, for a distance determined by the lenth of the drawn line. It is useful, for example, for giving the appearance of a cylinder.

  Radial

    The Radial gradient gives a circle, with foreground color at the center and background color outside the circle. It gives the appearance of a sphere without directional lighting.

  Square

    There are four shapes that are some variant on a square: Square, Shapeburst(angular), Shapeburst(spherical), and Shapeburst(dimpled). They all put the foreground color at the center of a square, whose center is at the start of the drawn line, and whose half-diagonal is the length of the drawn line. The four options provide a variety in the manner in which the gradient is calculated; experimentation is the best means of seeing the differences.

  Conical (symmetric)

    The Conical(symmetrical) shape gives the sensation of looking down at the tip of a cone, which appears to be illuminated with the background color from a direction determined by the direction of the drawn line.

  Conical (asymmetric)

    Conical(asymmetric) is similar to Conical(symmetric) except that the "cone" appears to have a ridge where the line is drawn.

  Spiral (clockwise)

    The Spiral tools provide spirals whose repeat width is determined by the length of the drawn line.

Repeat

  There are two repeat modes: Sawtooth Wave and Triangular Wave. The Sawtooth pattern is achieved by beginning with the foreground, transitioning to the background, then starting over with the foreground. The Triangular starts with the foreground, transitions to the background, then transitions back to the foreground.

Dithering

  Dithering is fully explained in the Glossary

Adaptive Supersampling

  Adaptive Supersampling is a more sophisticated means of smoothing the "jagged" effect of a sharp transiton of color along a slanted or curved line.

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