Trapcode Form

Base Form > String Settings Group

The String Settings group sets the size and basic appearance of the Box Strings base form. It is enabled when you choose the Box – Strings option in the Base Form pop-up.



Sets the density of the strings. Higher settings produce denser strings and take longer to render. The default value of 15 will generally produce good results, while values lower than 10 will cause the strings to degrade into dots. Very high values (in the hundreds, for example) can cause dense glowing lines because of the default Add transfer mode used to composite the particles.

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Left to right, Density at 1 and 8.

Size Random

Sets a randomness to the size of the strings. By varying the size of the particles that make up the string, this makes some strings thicker and some thinner.

Size Rnd Distribution

Controls the random distribution of smaller and thicker strings, and generates lines that appear randomly thicker or thinner across the form.

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At left, Size Random at 12, Size Rnd Distribution at 3. At right, Size Random at 12, Size Rnd Distribution at 7.

Taper Size pop-up

Applies a tapered string thickness at the ends of the strings with two options.

  • Off: No taper is applied.
  • Smooth: Offers a taper that starts closer to the center of the form, which makes the falloff more gradual.
  • Linear: Uses a linear falloff model, which causes the taper to only begin near the edges of the form.

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Left to right, Taper Size is Off, Smooth and Linear

Taper Opacity pop-up

Applies a tapered opacity at the ends of the strings with two options. Like Taper Size, these controls produce slightly different visuals.


  • Off: No tapered opacity is applied.
  • Smooth: Causes the ends to appear shorter and more transparent.
  • Linear: Only tapers the opacity close to the edge of the form.