Input Masks

You can mask most of the Hair Deformers input properties with various types of masks. Theirs value is clamped to: 0.0 - 1.0 range, thus if you have Noise Amplitude value set to 5, and mask is 0.5, then it will result in Amplitude of 2.5.
Masks can be stacked on top of each other, to create complex effects.

Note: The order matters: first top mask is evaluated then next to the bottom

To add mask click drop down menu icon on right and pick mask type

Color Attribute

Color Attribute: use vertex color attribute to mask hair effects. If multiple channels are used, then the average value is used for masking.

Curve Masks

Curve Influence Range

Similar to Influence Range mask but can be assigned to any type of deformer input property.

We use Quadratic falloff to control Duplicate Strands deformer falloff on the curve

  • Simple - gradually changes the mask falloff from 0 to 100%. Can be inverted.
  • Quadratic - gives you independent mask control on strand: beginning, center and end
  • BiDirectional - control mask falloff and value at both ends of the strand

Note: The main reason why Influence Range still exist - is that it can use 'Profile Curve' type of mask, which is not available in Curve Mask

Curve Attribute

Curve Attribute: Use Curve attribute to mask hair effect. This is intended to be used with Edit Curve Attribute feature in HTool

Edge Mask

Border Edge Distance

Border Edge Distance: Mask an effect based on the distance of strand from the mesh border. Above Aligned Tilt to Mesh Border only on strands that are closest to mesh border. It has invert option.

Edge Attribute Distance

Same as above, but uses user selected edge attribute to calculate distance between: strand and edge with attribute.

Invert

Invert: Not useful by itself, but placed after another mask, it will invert the previous mask effect

Length Mask

  • Assigns Min value to the shortest strands,
  • Assigns Max value to the longest strands.
  • Swapping Min and Max values will invert the effect

Math

Math Mask: Mostly useful for sorted strands, e.g. Strands From Grid Surface

  • Select N-th - select every N-th strand periodically: _ | _ | _
  • Wrap - slowly increase the mask value from 0 to 1, repeat periodically: /|/|/|
  • Ping-Pong - change mask value from 0 to 1 and back to 0, repeat periodically: /\/\/\

Vertex Group/Texture

Vertex Group/Texture: Use vertex group or texture for input masking

Object Vertex Group/Texture

Same as above, but samples vertex group/texture from custom object

Radius Mask

Radius Mask: Mask an effect based on strand radius. In video above I reduced noise on braids, at thinner places.

Offset/Gain

Mask Offset Gain: Not useful by itself, but placed after another mask, it can increase the mask contrast (gain) or brightness (offset)

Randomize

Randomize: Outputs random value for each strand.

Random value will be picked from within [x-RandRange; x+RandRange] bounds, where x - is any input value - e.g. from vertex group mask
You can disable lower/upper bound using </> buttons, thus limiting Random value range.

  • Rand Range - 0 - no randomization; 1 - maximum randomization
  • Variance < 0.5 outputs mostly smaller values, from within given range,
  • Variance == 0.5 all random values are drawn uniformly, from within given range,
  • Variance < 0.5 outputs mostly bigger values, from within given range,
  • Use Parent IDs - if enabled each child strand will inherit random value from its closest parent.

Procedural Mask

Procedural Mask: Use procedural noise texture to randomize hair look. No need for UVs

  • Min, Max - bring these values closer together to get sharper noise transition,
  • Scale - the bigger scale the more detailed the texture will be,
  • Distort - distorts the noise,
  • Offset - offset the noise sampling position

Viewport Mask

You can mask hair effect based on if the object is displayed in the viewport or rendered in final image. Can be used to reduce hair density in 3d viewport.

Influence Range

*Special mask that allows to modulate influence of deformer over strand length (e.g. taper only tip of strand).

Only available for some types of Deformers inputs - with 'Influence' in the name.

Types of Influence range masks:

  • Constant - the effect is uniform along the whole strand length
  • Simple - gradually changes the mask falloff from 0 to 100%. Can be inverted.
  • Quadratic - gives more detailed control. Modulate effect independently at strand beginning, center and end
  • Profile Curve - most detailed control using profile curve