3D Hair Brush is a powerful hair tool, including 3D brushes with Pie Menu, Use Radius Curve, Use Diameter Random, and Hair Modifier. 

3D brushes can distinguish complex muscle surfaces of models and provide artists with a wonderful experience of grooming hairstyles in Blender; With multiple well-designed brushes presets, it gives efficient solutions to making varying hairstyles;

Using Radius Curve makes it convenient for us to control hair shape; 

Using Diameter Random makes it possible to randomize the thickness of hair in just one particle system.

Modifier gives us an opportunity to add modifiers layer by layer until we get a good result and it doesn’t destroy any hair shape we created before.

Running Environment

Windows 10: Blender 2.93, 3.0, 3.1, 3.2

Mac os 10.15 and above: Blender 2.93, 3.0, 3.1, 3.2

Ubunto 18.04&20.04: Blender 2.93, 3.0, 3.1, 3.2

Installation

Click Edit -> Preferences -> Add-ons -> Install, select the Zip file, and hit Install Add-on.

Uninstallation 

1. Disable this add-on.
2. Save Preference settings, which is done automatically by default. 
3. Restart Blender, and then remove this add-on. 

Features

BRUSH

Options Enable 3D Brush: When a guide’s second point from the root is in the brush area, 3D brushes can work normally. Auto Switch: When enabled, the brush is toggled between 3D mode and 2D mode when it’s on or off the geometry. When disabled, there is no brush when it’s off the geometry. Brush Scale: When enabled, the brush can keep its scale in 3D space. When disabled, the brush can keep its scale in 2D space. Comb brush When Preserve Root Length is unchecked, guides can be moved along the surface of geometries. If you want to move the guides away from the surface, you can select the default Comb brush. 


Smooth BrushLength: Smooth the guides to make them average in length.
Add Brush
Length BrushTarget Length: It’s the limit when the guides are lengthened or shortened. Notice: It doesn’t work when set to 0.
Puff Brush


Weight Brush Increase, Decrease, Smooth: Modify weight smoothly  Strength: The strength of the weight brush. Note: Left click somewhere in 3D space to activate weight display, and the same operations to disable it when switching to other brushes.

Orient BrushOrient, Sunder, Repel: Orient brush only changes the orientation of the guides while keeping the original shapes. With the Curve enabled, the guides will be bent slightly.


Bend BrushBending guides.
Attract BrushCreating clamps.

Noise Brush Use Roughness: It works the same as the Roughness in the Children. Axes Locking: Disable the noise on one or more axes as per the locked axes.



Part Brush Modifying the orientation of the guides only.
Clone Brush Clone Source: Pick the source of the guides to be cloned. Clone Draw: Clone the guides at the position where this brush stays. Rotation Angle: The rotation angle of the clone brush which can also be achieved with the shortcut—CTRL + MOUSE WHEEL Note: It only works when the Enable 3D Brush is checked. It works only when location, and rotation are both set to 0, and scale is set to 1, as well as those in Delta Transform.
Color Brush Group the guides by different colors to avoid repeated selection. The color groups can be edited. Note:  Click anywhere in 3D space to activate color display after restarting a project, so that the colors can be displayed in Object Mode. Errors may occur in the color group when the number of guides changes. Try fixing the errors by hitting Hide Hair Color and display again. If it doesn’t work, you may need to delete the color groups and then recreate.  If there is just one color group, it’ll be deleted by default when a project is saved. You’d better not use Particle Settings repeatedly to avoid errors, because the data of Color groups are saved there. No need to worry if there is no color group.

Notes: The actual particles of Children cannot be updated in real time in the Particle Edit mode when 3D brushes are used. Switch to Object Mode to update.

PIEMENU

Hot Key Hit V to display the pie menu of brushes.  Hit J to display parameter menus.
Usage of Pie Menu




Customize Pie Menu

Use Radius Curve 

The following steps are required before using it. Switch the Render Engine to CyclesHair. Set the Hair Shape Type to Strip, and Additional Subdiv is optional under the Hair tab. Enable Use Radius Curve under the Hair Shape tab. Set the viewport shading to Material Preview Mode or Render Preview. Now, the shape of the guides are completely controlled by the curve. Curve settings can be saved as presets for later use at any time. Note:  In the CyclesHair render engine, Material Mode is just for displaying the thickness of hair. Strand Steps under the Viewport Display tab can be raised up somewhat if a high subdivision is required. At least one 3D viewport is required during rendering, or this function won’t work normally. When the render engine is switched to CyclesHair, the Cycles renderer is still used. When Use Radius Curve is enabled, adjusting parameters by dragging may cause display lag. Adjust the parameter again to fix it. 

Use Diameter Random

It takes care of setting random thickness for the hair in one particle system. Enable it, there are 3 additional parameters.
Random Seed:


Start: It ranges from 0-1, determining the smallest diameter. When reaching to 1, there is no random thickness.


Threshold: It ranges from -1 to 1, determining the amount of hair that is affected by Use Diameter Random. When it’s set to 0, all hair will be of random thickness, that is, all will be affected.  
Modifier


Modifier is Children based. And there are 3 common modifiers—Length, Clump, and Noise. Note: Please use the ABC Export (File -> Export -> Alembic HairModifier(.abc) ) when the works created by the Modifier need to be exported.
Every modifier comes with these 3 parameters which are used to control： Influence: It determines the influence degree of this modifier.  Seed: Random Seed, tweek it to find out a good result. Threshold: It controls the amount of hair that is affected by this modifier. The larger it is, the more the hair not affected by the current modifier will be.  When the Seed and the Threshold in a modifier are the same as in another modifier respectively, both modifiers will take effect on the same hairs. There are 2 Threshold parameters in Clump modifier: one controls clumping, the other controls kink effect.
There is Random by the side of many parameters. Enable it, there are 3 additional parameters below:  Seed: Random seed. We can modify it to randomize the effect of the current parameter.  Random Range: It controls the range of Random. Manual typing is required when it is greater than 1. The largest value is limited by each parameter itself. There is no effect when it’s 0. Threshold: It controls how much hair is randomized. When it’s set to 1, there is no random effect.
Vertex Group & Texture Vertex Group: Assign a vertex group as the mask where the current parameter works, the usage is the same as the default function. Texture: Set a Texture as the mask where the current parameter works.  Note: To ensure the accuracy of it, the texture needs to be in the Non-color color space, like Raw. Besides, unwrapped UV is required. Length Modifier: used to modify the length of hair。  Mode: Scale, scale up/down hair without hair shape change; Cut, cut hair off somewhat. Scale: determine the scale  Cut: determine the length of hair after cutting.  Note: the steps of hair won’t be reduced. Noise Modifier: basically the same as Roughness. Seed: Random seed of the noise.  Size: The size of the noise. Magnitude: The magnitude of the noise. It can be controlled by a curve.  Tip: The Magnitude is gradually getting larger from 0 to 1 from roots to tips.  Threshold: It controls the amount of hair affected by the Noise modifier, which is the same as the Threshold under Roughness. Preserve Length: Preserve the original length, to avoid being stretched. 
Clump Modifier
Options:  Factor: It controls how much the clumping is. When reaching 0, there is no clumping, but with Kink effect. Clump: it’s basically the same as the default parameter. Yet, there are some differences. No matter how much it is, the roots won’t be affected. 

Shape: It’s the same as the default parameter.  Tip: It can be controlled by a curve. When the curve is disabled, it’s linearly getting larger from 0 to 1 from roots to tips.  Preserve Length: Preserve the original length, to avoid being stretched.
Clump Type Parent: Clumps are generated according to the guides. Blender can run faster in this mode when a large amount of clumps are required.Subdivision: Split the clumps into multiple parts.  Note: The integer is needed.

Generated: Clumps can be generated randomly on the surface, and the amount is controllable without any influence of parent clumps. If you want to attract some clumps which have different parents, this type can help. Blender may run slower in this mode, and it’s recommended to use this type when only a few clumps are needed.
Seed: Random seed. Randomness: The randomness of clump distribution. 
Density: The larger it is, the more but finer the clumps will be.


textures. Add 2 clump types: Parent and Generated. Add ‘Use Diameter Random’.