Text Node

The Text node enables you to create and manipulate text for final output or for testing purposes. You can specify font characteristics, color, and opacity, as well as rotate, scale, and move the text layer.

Using the Text Node to Evaluate Expressions

You can enter expressions in the text field, such that the data referenced at any particular frame will be displayed in the monitor for that frame.

The simplest example is $F, which displays the current frame number. For example, when you type "$F" in the text entry field, the number "1" will be displayed in the monitor when viewing the first frame, the number "2" when viewing the second frame, and so on.

The ability to evaluate expressions may be most useful for displaying parameter data that you have animated in other nodes.

For example, you could access data from a Brightness node to display the current brightness value at each frame by using the Chalice ch function, with the expression surrounded by single back quotes (the " ` " symbol). You enclose the expression in back quotes to indicate that it should be evaluated, rather than being treated as text:

Current Brightness: `ch("brightness1/brightness")`

The above entry in the Text field would be displayed in the monitor as follows (where "0.5" is an example to represent the actual numerical value at the current frame):

Current Brightness: 0.5

To display the ` symbol as text, precede it with a backslash: \`

Note:
If you need more information about how to use expressions to access channel data, refer to the description of Data Channel Access Functions in appendix B.

The Text node requires one input, which may be any number of channels.

The output of the Text node will be the same number of channels as the input image, with the text composited into the RGB or RGBA channels.

The Text Node Parameter Tabs

The Text node features three tabs for creating and manipulating text: Text, Font, and Color.

The Text tab is where you enter and position text over the background. The Font tab provides parameters for selecting a font and adjusting spacing attributes. The Color tab controls the color of the text.

Text Parameter Tab

The Text parameter tab enables you to enter and edit the text to be used, to display the text layer in a work monitor, and to modify the text layer as a whole (by scaling, rotating, etc.). Transformations can be made using the interactive tool in the work monitor, or by keying specific values into the parameter fields.

Work Monitor / At Resolution

First, select a display resolution for the work monitor from the At Resolution popup menu. Then click the plus icon to display the work monitor for this node, which enables you to interactively rotate, scale, and translate the text over the input image.

Work Monitor Tools

The work monitor for the node includes a control device that features a boundary box and a circle-with-crosshairs tool:

Work Monitor Hot Keys

Hot keys can be used in conjunction with the work monitor tool to "nudge" the device in small increments, as illustrated below:

You can also use the Rotate, Scale, Translate, and Pivot parameters to enter precise numerical values for these operations.

Rotate

The Rotate parameter enables you to rotate the text layer relative to the input image. Alternatively, you can use the interactive controls in the Text work monitor to rotate the text layer.

A positive value rotates the text in a counterclockwise direction; a negative value rotates the text in a clockwise direction. The rotation is centered around a pivot point that you specify by using the Pivot parameter (see below). You set the Rotate parameter by keying in a numerical value specifying the degree of rotation, in the range of 0-360, or by using the mouse to set the tuner to the desired value.

Scale

The Scale parameter enables you to scale, or proportionally adjust, the text layer relative to the input image. Alternatively, you can use the interactive controls in the Text work monitor to scale the text layer.

You set the Scale parameter by keying in a pair of multiplier values in the range of 0-1 for the X and Y coordinates. For example, entering 0.5 in both data entry boxes will create a text area that is half as high and half as wide as the input image. The 0,0 point is the lower-left corner of the source image. Keying the values 1,1 in the data entry boxes will display the text area at full size (at the same size as the input image).

Translate

The Translate parameter enables you to shift the position of the text layer along the X and Y axes of the input image. Alternatively, you can use the interactive controls in the Text work monitor to translate the text layer.

You set the Translate parameter by keying in a pair of numerical values. The first value shifts the text area along the X axis (horizontally). The second value shifts the text area along the Y axis (vertically). The distance is measured as a percentage of the X or Y axis within a range of 0 to 1. For example, values of 0.5, 0.0 will shift the text to the right a distance equal to one-half the width of the input image.

Pivot

The Pivot parameter enables you to specify a pivot point to be used in conjunction with the Rotate parameter (see above). The pivot point is the center of the rotation.

You set the Pivot parameter by keying in a pair of values in the range of 0-1. These values represent an XY location specified as a percentage of the input image width and height. The lower-left corner of the image is the 0,0 point; the upper-right corner of the image is located at 1,1; the center of the image is 0.5, 0.5.

Text

The Text parameter is a data entry field in which you can type any text that you wish. (To format the text, use the parameters in the Font and Color tabs.)

Just as you can with other Chalice text entry fields, you can cut (Alt x), copy (Alt c), and paste (Alt v) text; select all the text in the field (Alt a); and add line breaks (Alt Enter). To bring up a separate text editor window, use the "Alt e" command.

To access and display expression data, refer to the section on Using the Text Node to Evaluate Expressions at the beginning of this node description.

Font Parameter Tab

The Font parameter tab enables you to specify font attributes for the text.

Font

The Font parameter enables you to specify the Adobe Type 1 PostScript font to use. Click the plus icon to bring up a standard Chalice Choose File dialog. Navigate to the directory containing the font you wish to use and double-click on the font name.

Chalice provides several sample typefaces: Baskerville (in roman, bold, and italic fonts), Brush Script, and Liquid Crystal. They are located in the "psfonts" directory in the Chalice support directory. You can place additional fonts in this directory, or navigate to any directory that contains the font you wish to use.

Tip:
Use a monospace font such as Courier to display parameter values in diagnostic applications of the Text node. The equal width of all characters in monospaced fonts keeps the changing parameter values from seeming to jump from frame to frame.

Tolerance

The Tolerance parameter enables you to specify the level of tolerance applied as each letter is drawn on screen.

As you raise the tolerance level, fewer lines are used to approximate each letter shape. This means that for the most accurate representation you should use a low tolerance value, such as the default value of 0.5.

For faster rendering, especially when you are using the Text node for testing purposes rather than final output, specify a higher tolerance value. You may also want to experiment with high tolerance values for creating interesting and unusual letter shapes.

Alignment

The Alignment parameter enables you to specify that the lines of text be aligned flush left, flush right, or centered in the text layer by selecting an option from the popup menu. The default is centered text.

Letter Space

Use the Letter Space parameter to scale each letter to increase or decrease the space between letters in each line of text, within the current boundaries of the text layer. (This operation is somewhat analogous to kerning in the printing process.)

Line Space

Use the Line Space parameter to scale each letter to increase or decrease the space between lines of text, within the current boundaries of the text layer. (This operation is somewhat analogous to leading in the printing process.)

Anti-Alias

The Anti-Alias parameter enables you to specify the level of anti-aliasing to be applied to the text by selecting one of these options from the popup menu: None, 2x2, 4x4, 8x8 (the default), 16x16 or 32x32.

These values define the size of the grid into which a pixel is divided during the anti-aliasing process. The greater the number of subpixels, the higher the quality will be and the longer the process will take:

  • If you select "None," the resulting text will suffer from severe aliasing, which is the jagged, staircase effect visible in diagonal lines and curves.
  • For previews, "2x2" should be adequate.
  • Both "4x4" and "8x8" will likely produce very effective anti-aliasing, but if necessary you can select even higher quality.
  • Settings higher than "8x8" will slow down rendering considerably.

Color Parameter Tab

The Color parameter tab enables you to specify the color and opacity of the text.

Color

The Color parameter enables you to specify the color values of the text using RGB or HSV color space. The default mode is HSV. Click the RGB button to switch to RGB mode. The Color tab display will update to present RGB sliders in place of the Hue, Sat, and Value sliders.

HSV Mode

To specify the Hue, key a value in the range of 0-360 into the data entry field, or use the slider bar to select the desired hue. The Sat(uration) and Value parameters are specified in the same way, within a range of 0-1.

RGB Mode

You specify RGB values by keying in a value in the range of 0-1 or by using the slider bars.

Alpha

The Alpha parameter enables you to control the alpha channel value that is output from the Text node for compositing in another node. This parameter setting is only relevant when the input image has an alpha channel, and it affects the value of pixels with text-layer coverage only.

(To adjust the transparency level of the text as it appears in the Text node display, use the Opacity parameter instead.)

You can key a value in the range of 0 (transparent) to 1 (opaque) into the data entry field, or you can use the tuner to set the desired value.

Opacity

The Opacity parameter enables you to specify the opacity of the RGB channels in the text layer without adjusting the alpha channel, or if the input has no alpha channel. Key a value in the range of 0-1 into the data entry field, or use the tuner to set the desired value. A value of 0 represents total transparency; 1 is totally opaque.

This parameter adjusts RGB channel values of the relevant pixels and not the alpha channel value, if there is one.




Table of Contents | Index



Copyright 1996-1999 by Silicon Grail Corporation