Build Modifier

The Build modifier make strokes appear or disappear in a frame range to create the effect of animating lines being drawn or erased.

Options

Mode

Determines how many strokes are being animated at a time.

Sequential

Strokes appear/disappear one after the other, but only a single one changes at a time.

Concurrent

Multiple stroke appear/disappear at a time.

If enabled you can set the Time Alignment.

Time Alignment

Align Start: All stroke start at the same time (i.e. shorter strokes finish earlier).
Align End: All stroke end at the same time (i.e. shorter strokes start later).

Transition

Determines the animation type to build the strokes.

Grow: Shows points in the order they occur in each stroke, from first to last stroke. (Simulating lines being drawn.)
Shrink: Hide points from the end of each stroke to the start, from last to first stroke. (Simulating lines being erased.)
Fade: Hide points in the order they occur in each stroke, from first to last stroke. (Simulating ink fading or vanishing after getting drawn.)

Start Delay

Number of frames after each Grease Pencil keyframe before the modifier has any effects.

Frames

Maximum number of frames that the build effect can run for. (Unless another Grease Pencil keyframe occurs before this time has elapsed.)

Factor

Use a defined percentage factor to control the amount of the stroke that is visible.

Object

Object to use as the start position of the build transition.

If enabled, only modify strokes during the specified frame range.

Factor: Defines home much the stroke is fading in/out.
Thickness: How much strength fading is applied to the stroke's thickness.
Opacity: How much strength fading applies to the stroke's opacity.
Weight Output: Assign a weight value to points that have started/finished the fade.