Adobe Illustrator CS-CS5 Drawing Tool Tutorials
All Tutorial Text & Images - Copyright © 2011 KHI, Inc.
In Adobe Illustrator CS, and later versions, tonal gradations are rendered via the Gradient Mesh tool (U) and the Gradient Tool (G). The Gradient tool is fairly straightforward in its approach to rendering a gradation and blending subtle tonal and color gradations. On the other hand, the Gradient Mesh tool is one of the more labor intensive and frustrating tools in the Illustrator tool palette, especially for the Illustrator newcomer. Once you become comfortable with this tool you can create seamless blends and gradations that are infinitely scalable in vector format, making the final file far more versatile than a Photoshop raster file.
Gradient Palette Attributes: The Illustrator Gradient Tool (G) is accessed through Illustrator's Tool palette (Fig. 1). Once a simple gradation has been created it is controlled through the Gradient palette shown in Fig. 2. A gradation is created by selecting a contained shape (square shown in Fig. 3) and dragging across it with the Gradient Tool (G). You will notice that the white-to-black gradation is indicated in the Gradient palette shown in Fig. 2.
Gradient Mesh Tool Attributes
Tonal gradations can also be created via Illustrator's Gradient Mesh tool (U). This tool is used to render complex gradations and shapes. It is also accessed through Illustrator's Tool palette (Fig. 4). Once a gradient "Mesh" has been created (Fig. 5) you will notice a grid pattern overlaying your shape. The grid is controlled in much the same way as you would control Illustrator's Pen Tool. You can drag anchor points and add them just as you would with the Pen tool.
Unlike the Gradient Tool (G), the Gradient Mesh tool does not make use of the Illustrator Gradient Palette shown in Fig. 6. It is totally controlled by manipulating the anchor points on the grid "mesh". You will notice that the center anchor point in Fig. 5 is active (solid) and that the grey color it is introducing into our black square is shown as the "Fill" color on the Tool palette (Fig. 4).
Using the Gradient Tool's Linear and Radial settings
In this demonstration we will create a matt finished metal tube using only the Illustrator Gradient Tool (G). For this type of gradation we will "Gradient" Palette to "Linear" in the pull-down menu. By clicking on the gradient bar in the Gradient Palette (Fig. 8), you can add new gradation points. This gives you the multiple banding effect that is necessary to render a reflective metallic surface. You will see that our new gradation is shown as the "Fill" color on the Illustrator Tool palette (Fig. 7). You control the color that each new gradation point introduces by double clicking on that point and using the "Color Palette" to modify its color properties.
In Fig. 9 we have hardened up the gradation to simulate a highly reflective chrome surface. This is achieved by moving the gradation points closer together thereby shortening the span of each gradation step.
In this palette window you can also adjust the angle of the gradation from 0° to 360° by using the "Angle" setting in the pull-down menu. In our example above we have set the angle to zero degrees. If you were illustrating a sphere instead of tubing you would set the "Gradient" palette to "Radial" in the pull-down menu. This would create a radial gradation that emanates from the center of your defined path.
Using the Gradient Mesh tool
In this next demonstration we will create a convex shape using the Illustrator Gradient Mesh tool (U). We will start out with a simple shape (Fig. 11). Once a gradient "Mesh" has been established to our shape (Fig. 12) you will see our grid pattern overlaying the shape. At this stage all anchor points are active (solid). Now we will click on the center anchor point to activate it and deactivate all of the other surrounding points. Once again you will notice that the center anchor point in Fig. 13 is active (solid) and that the white color it is introducing into our grey shape is shown as the "Fill" color on the Tool palette (Fig. 10).
As was stated in the preceding paragraph, you can control the illusion of shape by dragging or adding anchor points to the mesh grid. This will change the location and intensity of the gradation thereby affecting the shape. Remember to control the mesh anchor points in the same way that you would control the anchor points along a Path or Stoke.
In Fig. 14 we see our shape as it is integrated into the final image. All of the anchor points have been selected and the "Fill" color on the Tool palette will show a "Question Mark" to indicate that there are multiple colors at work in the selection.
Pushing the limits of Illustrator's Gradient Mesh
This is a very basic lesson in the use of the Illustrator Gradient Mesh tool and its ability to create smooth gradations and blends. Using the techniques discussed in this tutorial there is no limit to the complexity of the subject matter you can render with these tools. Fro an example of just how far you can take Adobe Illustrator's Gradient Tools, check out the article on Yukio Miyamoto's work in Illustrator (samples below).
Perhaps the single greatest limitation on how far you can go with this tool is the file size, and its ability to drastically slow down screen redraws. This is especially annoying when dragging the file with the Hand Tool while zoomed in to the image. If this is the case, you will want to set the "View" mode to "Outline" which will turn off the tonal color work, thereby speeding up screen redraws. Note: The following hardware and software was used in this tutorial: Apple Mac Pro, a Wacom Intuos 6x8 drawing tablet and Adobe Illustrator CS-CS5 vector drawing software.
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