Hair Node

HAIR NODE

Hair Node is another settings node in FurryBall, it is connected directly to a mesh that has hair system attached. Hair node describes mainly the final looks of hair, base geometry and dynamics is set elsewhere (see Hair System section).

Note that hair node attributes have effect only if Hair feature is enabled in currently active render node (see Render Settings Node section).

Unlike other settings nodes hair node is attached to a hair system by default so there is no need to do this manually.

Attributes

Most of the hair node's attributes are related to hair curves, just few of them to guides and Maya curves. See Hair System section for more details on the hair system 3-level hierarchy.

• HAIR GUIDES - Only attributes in this section are related to guides which means they have influence on both guides and hair curves.

• CVS Per Guide - Number of control vertices (points) per guide curve. This is set when creating hair system but it is possible to change the number of control points whenever needed. Note that changing this can change the looks of the hair greatly so it is good to set this parameter before setting anything else. Also note that the number of control points per guide has major influence on hair geometry complexity. Typical use is:

• 2 - leaves (no surface deformation)
• 4 - fur
• 8 - longer fur or short hair
• 16 - hair
• 30 - long hair

• Guide Length - Guides' length is also set when creating hair system but can be changed here whenever needed.

• B-Spline - When turned on, higher quality B-spline interpolation is used to generate hair geometry. When turned off, linear interpolation is used. This parameter together with CVS Per Guide and Curve Smoothness affects hair smoothness.

• HAIR CURVES - Attributes in this section are related mainly to hair density and curves' size.

• Render - Enable or disable rendering of this hair system. Useful for some tweaking or resolving performance issues.

• Curve Smoothness - This parameter affects smoothness of the final rendered hair curves. If guide curves have enough control points (see CVS Per Guide attribute above) and thus hair geometry is smooth enough it is not necessary to modify this parameter. If hair geometry is just minimalistic and most of the modifications is to be done here on the hair curves it is good to increase smoothness when needed. Hair smoothness is in fact number of control points per hair curve segment, where segment is part of curve between two guide control points (see CVS Per Guide attribute above). This means that the final rendered curve has (approximately) guideCVS * smoothness control points.

• Density - Number of hair curves (or clumps) per unit area on mesh surface. Density does not depend on size of mesh or its complexity, this is very important as it is possible to create a hair node preset and use it on several meshes without the need to adjust density for each mesh if its size or complexity differs. But if mesh is scaled after creating hair on it the density remains the same. Please note that this parameter has major impact on performance. If the performance is very low but density is not high enough try to decrease CVS Per Guide and/or Hair Smoothness. There are two objects with different size but same density in the picture below.

• Density Map - Density multiplier as a texture mapped to the mesh's surface using its primary UV set. Color intensity is used as multiplier (zero for black and one for white).

• Curves Per Clump - Clumps are groups of hair curves with similar properties. There are no clumps by default when you create hair system, if you increase Hairs Per Clump all hair curves are replaced with groups of hair curves - clumps. Note that clumps can increase total number of hair curves dramatically so it is sometimes good to decrease overall density. Clumps have its own parameters described in Hair Clumps section below.

• SHAPE
• Scale - Scale rendered hair curves only (not hair guides).

• Length - Change length of hair curves only (not hair guides).

• Billboard - If checked (default), generated hair geometry always faces the camera. This is useful for long, thin hair. When turned off, hair geometry orientation is randomly generated and fixed. This is useful for rendering leaves or other bigger pieces of hair.

• Min Billboard Width - Minimum width of billboard hairs in pixels. Useful for disappearing hair in distance. Hairs will not be rendered smaller than this value.

• Min B. Width in Shadow - Minimum width of billboard hairs in shadow map pixels.

• Orientation - Hair geometry rotation about its normals, 0-360 degrees. Works while billboarding is off.

• Orientation randomness - Setting this value to 1 causes complete randomness in hair orientation. Setting of 0 causes all hair planes to be parallel, depending on normals.

• Offset Map - Map a texture that will offset hair along their normals (vertically), using mesh's primary UV set.  Use texture color balance attributes to adjust the offsets.

• Length Map - Length multiplier as a texture mapped to the mesh's surface using its primary UV set. Use texture color balance attributes to adjust the lenghts.

• Length Randomness - If non-zero hair curves' length will vary from curve to curve.

• Length Random Probability - Has effect only if Length Randomness is non-zero. Values near zero mean there is higher probability that hair curves will be shortened (most curves will be short, only few longer). Values near one mean there is higher probability that hair curves will be prolonged (most curves will be long, only few shorter).

• Root Width - Width of hair curves' roots.

• Tip Width - Width of hair curves' tips.

• Width Randomness - Adds randomness to hair curves' width if non-zero.

• Tip Softness - Hair curves' tips are blended slightly to make tips softer. It is recommended to use this parameter only when Jitter Multisampling is enabled (see Render Settings Node section) as it is related to this technique.

• Border Softness - Blend hair curves' vertical borders. See previous attribute.

• HAIR CLUMPS - Clumps only section, modifications and other parameters related to clumps. Clumps are groups of hair curves with similar properties. There are no clumps by default when you create hair system, if you increase Hairs Per Clump all hair curves are replaced with groups of hair curves - clumps. Note that all other attributes outside of this sections take clump as a single hair curve, ie. all modifications are made to all members of clump. If seme parameters are meant to vary from curve to curve (all randomness attributes) they vary from clump to clump in fact.

• Clump Base Radius - Every clump has its center it was created from (original single hair curve when clumps are disabled), other clump members grow in a circle around the center, base radius is maximum distance between the clump center and any clump member.

• Clump Inclination - Clump members grow in a circle around clump center and can be bent towards the center (positive values) or away from it (negative values) using this parameter. See picture above with relatively high positive clump inclination.

• Clump Length Randomness - Hair curve length randomness affects all clump members, there is no randomness in length of particular clump members. This parameter adds length variations to clump members.

• Clump Kink - Similar as with length randomness, hair curve kink is applied to clump as a whole. This parameter adds length variations to clump members. See Kink attribute below for more details on kink.

• Clump Mutant Rate - Mutant rate attribute in Hair Color section is an exception from other clump attributes, it creates mutants not from clump as a whole but from single hair curves - members of clumps. Using clump mutant rate it is possible to make a mutant from a clump as a whole - all members will be mutants. See Mutant Rate attribute below for more details on mutants. See picture below - left picture shows Mutant Rate attribute effect and right picture shows Clump Mutant Rate attribute effect.

• HAIR MODIFICATION

• Bend Angle - Angle in degrees to bend all hair curves to.

• Bend Direction - Direction angle in degrees for bending and inclination. Default direction (zero angle) is positive V axis from UV texture coordinate system taken from primary UV set of the mesh.

• Bend Randomness - Bending/inclination angles and direction will vary from curve to curve if non-zero.

• Inclination - Inclination angle in degrees. Unlike bending inclination does not bend the shape of hair curve, it rotates hair curve as a whole. Bend direction is used to determine the direction for inclination.

• Waviness - Waviness adds the effect of wavy hair. Waviness frequency and smoothness depend on CVS Per Guide and Smoothness attributes. Increase CVS Per Guide for higher frequency and Smoothness for smoother waves.

• Kink - Adds kink effect to hair. Kink just randomly shifts control points along the curve, ie. kink frequency depends on total number of hair curve control points (see Hair Smoothness).

• Kink Frequency Limit - This is just to decrease kink frequency, it means kink is only applied to every Nth control point.

• HAIR COLORS

• Root Color - Color of hair curves' roots, if texture is used texels are mapped to the mesh's surface using its primary UV set.

• Tip Color - Color of hair curves' tips, if texture is used texels are mapped to the mesh's surface using its primary UV set.

• Body Color - Color of hair curves' bodies, if texture is used texels are mapped to hair curve (bottom of texture is mapped to hair curve root).

• Alpha Mask - Check this and use the alpha (4th) channel of hair 'Body Color' texture as an alpha mask. Pixels with alpha intensity less than 0.5 will be discarded. Use this setting for grass or leaves rendering.

• Alpha Mask Mipmap Fix - Use alternative alpha mipmap generation method ("max" instead of "average" filter). This helps with thin features disappearing in distance.

• Hue Variance - Adds randomness to final hairs' color hue. Hue will vary from curve to curve if non-zero.

• Saturation Variance - Adds randomness to final hairs' color saturation. Saturation will vary from curve to curve if non-zero.

• Value Variance - Adds randomness to final hairs' color value. Value will vary from curve to curve if non-zero.

• Mutant Rate - Rate of hair curves (clumps) that will be mutants. Mutants are special hairs with their own color different from other hair curves.

• Mutant Color - Mutant color for all mutants in hair system, if texture is used texels are mapped to the mesh's surface using its primary UV set.

• Mutant Color Fade - Rate of original (non-mutant) color to be added to mutant base color.

IMPORTANT NOTE: If no special shading is enabled material shader linked to source mesh (mesh with this hair system attached) is used. Also some material attributes are shared - ambient color and incandescence color.

• HAIR SHADING - Hair usually needs special techniques when shading. However furs or very short hair can be shaded using standard shading models. Attributes in this section are related to special shading attributes if they are enabled and special shadow attributes if hair shadows are enabled (see Render Settings Node section).

• Long Hair Diffuse - Special hair shading technique for diffuse color will be used if enabled. This method is better for longer hair, not very suitable for fur.

• Long Hair Specular - Special hair shading technique for specular color will be used if enabled. This method is better for longer hair, not very suitable for fur. Other specular attributes are used if enabled, two shifted specular colors are used, see attributes below.

• Normals - Type of normals used for hair shading. Vegetation shading always uses hair surface normals.
• Mesh Normals - Shading normals are taken directly from the underlying mesh. This might be useful for short hair and fur.
• Hairs - Hairs will be shaded along their curvature.
• Hair Surface Normals - Individual hair face/surface normals are used. This is similar as using a standard shading model such as Blinn.

• Leaf Translucence Focus - Works only with vegetation shading. Maximum focus means that light translucence from back faces will be concentrated against light.

• Vegetation Shading - EXPERIMENTAL vegetation shading suitable for leaves and foliage. If enabled, hairs will take colors from the Vegetation Colors attributes, instead of Body Color, etc. Alpha masks will still apply.

• Specular Color 1 - Primary specular color for hair specular shading only.

• Specular Shift 1 - Both specular colors are shifted slightly when specular shading is enabled. This parameter can be used to adjust primary specular color position shift.

• Specular Exponent 1 - Primary specular color exponent (similar to Blinn exponent parameter).

• Specular Color 2 - Secondary specular color for hair specular shading only.

• Specular Shift 2 - Both specular colors are shifted slightly when specular shading is enabled. This parameter can be used to adjust secondary specular color position shift.

• Specular Exponent 2 - Secondary specular color exponent (similar to Blinn exponent parameter).

• HAIR SHADOWS - Not just special shading is needed but also shadows require special treating. Shadow attributes from light node (see Light Node section) are not used for hair rendering, use these attributes below to adjust some shadow parameters. Note that variable penumbra shadows are not supported for hair (received shadows only).
• Shadow Filter Radius - Same as Filter Size attribute in Depth Map Shadow Attributes section of light shape node. This parameter adds the soft shadow effect if greater than one.

• Shadow Volume - Tuning parameter for volumetric shadows simulation, it allows shadow intensity adjusting of deeper hair layers (regions closer to source mesh's surface).

• Curve Width In Shadow - Tuning parameter for removing alias from cast shadow. Hair is usually represented with extremely high frequency geometry, which is not good for depth map shadows. Width of hair curves can be temporarily enlarged using this parameter when casting shadow.

• Shadow Intensity - This multiplier parameter allows to adjust shadow intensity received by hair.

• Shadow Bias - If set to non-zero, this attribute overrides received shadow bias on hair. See the Lights sections.

• AO Intensity Out - This parameter allows tuning of AO shadow that comes from this hair system, ie. importance of this this hair system as an occluder for other meshes.

• AO Intensity Received - This parameter allows per mesh tuning of AO shadow received by this hair system from other meshes.

• Hair Opacity - Hair opacity for usage with deep shadow maps (transparency shadows). Zero means fully transparent and one fully opaque hairs.

• Shadow Method - Method for hair shadow creation. If a light isn't enabled with the more advanced shadow mapping methods, hair shadows always fall back to standard shadow maps.

• VEGETATION COLORS - Colors intended for experimental foliage shading. Only used when Vegetation Shading enabled.
• Leaf Front Color - The front face color texture. Alpha mask is taken from its alpha channel.

• Leaf Back Color - The back face color texture.

• Leaf Normals - Normal map texture. Use standard normal maps, where (0.5, 0.5, 1.0) means no bumps.

• Leaf Thickness - Thickness texture. Black means minimum thickness, white maximum thickness. This attribute is used to fake leaf translucence.

• COLOR BLEEDING - Tuning parameters for color bleeding on a per hair system basis.
• CB Intensity Out - This parameter allows tuning of color intensity that comes from this hair system, ie. importance of this hair system as an color emitter for other meshes.

• CB Intensity Received - This parameter allows tuning of color received by this hair system from other meshes.

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