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Masking

You have already learned about what shape or mask is in previous lesson. We even learned the relationship between clips and shapes. In this page, we learn about how to use an automation script to create mask.

Shapery

automation menu The script we use is called Shapery so download it from Dependency Control. Shapery is an script for all things related to Shapes. Shapery has a lot of sub-menus. We will run out of keys if we bind them all to hotkey so we will use it from the Automation menu itself but if you find yourself using a sub-menu a lot, you can bind it to hotkey.

When you install Shapery, it will make two entries in the Automation menu: : Shapery Macros : and Shapery. Both of these have sub-menus and we will talk about the sub-menus that I find the most useful.

Shapery Macros

Clip to Shape

clip to shape example 1

Nichijou Episode 5: 0:21:10

Signs like this is where we apply mask. We can cover the box with a black mask and put the text over it. Follow the steps below to convert clip to shape:

  1. Draw a clip (rectangular or vectorial).
  2. Go to Automation -> : Shapery Macros : -> Clip to Shape.
  3. Open Edit Tags and make necessary changes (color, border, opacity etc)
  4. Put text over it.

clip to shape example 2

Kaguya-sama: Love is War Episode 1: 0:06:50

The Japanese text here is unfortunately vertical. While kanji may be read vertically, English text is not meant to be read vertically. This is why we will not mask over the original text. We can instead put the mask above the box.

Shape to Clip

Since we can convert a clip to shape, we can do the reverse as well. The main reason why we would want to do this is to convert the shape to clip and change the coordinates of the clip using Aegisub tool and reconvert it back to shape.

Another reason would be to convert the shape to clip and use this clip in other lines. This way other lines will be clipped inside the shape.

Although the name says Shape to Clip, if you have a text and run this the text will directly be converted to clip.

Shape Clipper

If a shape has clip, then this menu removes the portion of the shape that the clip tag removed which means the clip tag is no longer used but its appearance remains unchanged.

So what is the use of this menu if it removes already invisible portion of shape? If you remember past lesson, clip creates hard edges that even the blur tag does not fix. Removing clips this way is one of the ways of solving this problem.

If you run this in the line with text, the shape is first converted to shape and then that shape is clipped.

Shape Expand

Shape Expand bakes in as much tag as it can like scale, perspective etc into the shape itself. Think of it like the shape uses the least amount of tags but keeps the original appearance of the shape.

If you run this in a line with text, it just converts it to shape. This is the recommended way to convert text to shape.

Shape Merge

You can select the multiple lines with shapes and running this menu will merge all these shapes into one line.

Warning

This method is just taking the drawing commands and appending it to a single line. If you want to merge all the shapes into a single shape, there is another method below.

Shape to 0,0

This will keep the appearance of the shape but change the position of the shape to (0,0).

Shape to Center

This will keep the appearance of the shape but change the position of the shape to the center of the bounding box of the shape.

Shape to Origin

This will keep the appearance of the shape but change the position of the shape to the origin of the shape.

Shape trim

If you select multiple lines and run this menu, it will remove all the portion of the lower shape that has been covered by shape above it. It does not seem to respect the layers. It will trim with respect to the last line in selection.

Shapery Sub-Menus

Manipulate

manipulate gui

There are two things you can do in Manipulate: simplify the drawing command or flattening the drawing command. Both of these are used to clean up the drawing commands.

Flattening means converting a complex path which is made up of numerous bézier curves into a series of small straight line segments.

Simplifying means reducing the number of points or segments in the drawing command while keeping the original appearance of the shape.

The variables of simplify:

Variable Meaning
Tolerance How far the simplified shape is allowed to deviate from the original shape
If deviation of a point is more than tolerance, point is not simplified
Angle Threshold How much can a curve be simplified to a straight line

So higher the value of the variables, the more the shape changes due to simplification. The lower the tolerance, the less simplification occurs.

The variables of flatten:

Variable Meaning
Distance Maximum distance between curve and the approximated straight segments

So higher the distance, the coarser the approximation is but has lesser line segments. The lower the distance, more detailed the approximation is but also has more line segments.

In the GUI, if Fit Curves is enabled, the script will try to approximate the curve for it while simplifying else it will use line segments.

If Execute On \clip is enabled, the simplification or flattening will be executed on the clip of the line not the shape.

Offsetting

Offsetting is used to expand or contract the shape.

  1. Go to Automation -> Shapery -> Offsetting.
  2. In the GUI, set the stroke weight to a positive value to expand and negative value to contract the shape.

  3. In the corners style, select how sharp the corner is after offsetting:

    Corner Sytle Meaning
    Miter Sharp, pointy and angled corner
    Round Curved corner
    Square Flat and squared corner

  4. Stroke here refers to border. Align stroke tells the script where the border should be placed relative to shape.

    Align Stroke Meaning
    Center Border is centerd on path i.e. half of border covers shape, half is outside the shape
    Outside Border is completely outside the shape
    Inside Border is completely inside the shape

  5. Miter Limit determines the maximum allowed sharpness before switching to a flat bevel corner

  6. Arc Precision determines how accurately offsetted curves are approximated with straight lines. (Higher precision means use more line segments means smoother curve)

Pathfinder

pathfinder

This menu provides a way to perform boolean operation on shapes. You either add clip to a line and operate between the drawing command of clip and drawing command of shape.

Or you select multiple lines, click on Multiline and operate on the drawing commands of all the lines.

In the dropdown, you will find four options:

Unite

Combining all shapes into one shape.

Mode Operation
Single Line Mode Combines the shape with its clip
Multi Line Mode Shapes of all lines is combined into one

This is the alternative to shape merge as mentioned above.

Intersect

Keeping region shared by all shapes.

Mode Operation
Single Line Mode Keeps the region overlapping between shape of a line and clip
Multi Line Mode Keeps the region overlapping between shapes of all lines

Difference

Think of carving out a piece from a shape.

Mode Operation
Single Line Mode Removes the region that is covered by clip
Multi Line Mode Removes the region in the first shape that overlaps with all the other shapes
Does not seem to respect the layers

Exclude

This is inverse of Intersect i.e. removing region shared by all shapes.

Mode Operation
Single Line Mode Removes the region overlapping between shape of a line and clip
Multi Line Mode Removes the region overlapping between shapes of all lines

Masks with fades

Signs that have fades is difficult to mask because during the fade, the original text underneath will be visible. So how do we deal with such signs?

Don't use mask

One thing you could do is of course not to use mask. Put the text outside the sign somewhere and fade it like usual.

TODO: Add example

Just use fade

Add the fade like normal and see if it looks bad or not. In cases when the fade is short, the problem of original text being visible might not even exist.

TODO: Add example

Shorten the fade

You could also shorten the duration of fade. Do this and check if the shortened fade looks off or not.

TODO: Add example

Extend the duration of the sign

You could make the sign start earlier and add fade in or make the sign end later and add fade out such that the fade in and fade out occurs when original sign does not even exist in the background while the sign is opaque during the original fade.

TODO: Add example

Animate the color

Keep the mask fully opaque and animate the color instead. This works well for signs that fade to or from a color, or signs that appear over a background that's largely a single color.

TODO: Add example

Recreate the background

This is of course not always easy and the results are not always satisfactory. Not to mention, it takes long time.

I had to work in this sign:

One Pace - Wano 35: 0:26:56

I chose to recreate the background for this sign since the fade is quite short. The background also moves so this added another layer of complexity. So I chose to recreate a big background, clip it and then use \move tag to move the background since the movement was linear. Then I created the white mask over it.

I added the background but only during the duration of fade.

Then I added the white mask throughout the duration of the line.

Then I finally added a text with fade.

Multiple Drawing Commands

A single drawing command starts with the command m and ends only when the next m command is encountered. Aegisub's tools only allow you to draw a single drawing command so if you want to draw multiple drawing commands, you'd have to do it manually by typing.

You could of course draw multiple shapes in multiple lines and merge them as I demonstrated above. However, there is a better way. We will be using a script called New Clip Shape by petzku. As soon as you install it from Dependency Control, bind it to a hotkey but not in Subtitle Grid section but in Video section. This is because as we are drawing clip, we want to press this hotkey to start a new shape. I personally bind it to letter n in Video section.

  1. Draw the first shape normally using clip.
  2. After you draw the first shape, draw the first point of next shape. It will look odd since the last point of the first shape and first point of new shape are connected
  3. Press the hotkey that runs the script New Clip Shape. This will disconnect the last point of the first shape and first point of new shape. All this is doing is inserting m before the last coordinate.
  4. Continue drawing the second shape.
  5. Repeat.

Masks with Hole

If you want to draw masks with hole, you could again use Shapery like I demonstrated above or you could draw the clip in such a way that creates holes. You could draw the clip in clockwise direction or anti-clockwise direction. Most of the time, it would not make much of a difference but if you draw shapes in the same line in opposite direction, it will create a hole in the shape.

You could start drawing clockwise and then draw an anti-clockwise hole or vice versa.

mask with hole

Hoshikuzu Telepath Episode 06: 00:09:35

Take this example. When you draw the shape above, you would cover the notes as well. When you draw the clip here, you can at the same time draw the holes too. I'm doing sloppy job drawing clips. Please be better than me when you are actually typesetting.