| Illumination | Transparency | Indirect Illumination | Render Tree Usage
Shader Type: Material
Output: Color (RGBA) value
Controls the diffuse, ambient, and specular RGB colors, transparency, and indirect illumination of hair objects using gradient sliders so that you have a high degree of control over where the shading occurs on the hair strand.
Name |
The shader’s name. Enter any name you like to give it a unique identity, which is especially useful when selecting hair elements. |
Diffuse
Enable Diffuse Shading |
Uses the diffuse color settings for the hair as defined with the regular color controls. |
Use Diffuse Gradient |
Uses the diffuse color set with the gradient slider that appears when you select this option. |
Gradient Slider |
The gradient slider determines the diffuse color value along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. • The small circle marker at the top of the slider is the interpolation markers. This marker is always between each pair of color markers (square markers), indicating the mid-point in the blend between those two colors. Moving the circle closer to either color marker causes less of that color, and more of the other, to appear in that “sub-gradient”. The net effect is a sharper blend and a larger portion of the dominant color. • Square markers on the bottom of the gradient bar are color markers. You can add up to 8 color markers, each with their own color. Clicking on the gradient slider inserts a color marker at the click-point. By default, the new marker assumes the color of that point in the gradient. To delete a color marker, right-click it and choose Delete marker from the menu or press Delete. Color controls: Controls the R, G, B, and alpha values for the selected color marker. Value slider: Sets the overall color value for the gradient slider. Pos:.Controls the position of markers on the gradient slider: - Color Markers (squares): If a color marker is selected, the Pos value indicates its position, on a scale of 0 - 1, within the entire gradient. - Interpolation Markers (circles): If an interpolation marker is selected, the Pos value indicates its position, on a scale of 0 -1, between its associated pair of color markers. Cubic/Linear: Switches between linear and cubic interpolation of the gradient. Cubic interpolation results in a smoother transition between alpha values, while linear interpolation results in sharper transitions. |
Ambient
Use Ambient Gradient |
Uses the Ambient color settings for the hair as defined by the gradient slider that appears when you select this option. If this option is off, the ambient color settings are defined with the regular color controls. |
Gradient Slider |
The gradient slider determines the ambient color value along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. The gradient slider options are the same as described for the Diffuse Gradient parameter above. Ambient color is weighted by the scene’s global ambience. |
Diffuse / Ambient Blending
Use Blend Gradient |
Uses the Blend color settings for the hair as defined by the gradient slider that appears when you select this option. This determines what percentage of the diffuse and ambient colors are used on the hair. |
Gradient Slider |
Determines the diffuse and ambient color blend along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. A value of 1 means that both Diffuse and Ambient are visible, and a value of 0 means that only Ambient is visible. The gradient slider options are the same as described for the Diffuse Gradient parameter above. |
Specular
Enable |
Enables the calculation of specular highlights and uses the Specular color settings for the hair as defined with the regular color controls. |
Use Specular Gradient |
Uses the Specular color settings for the hair as defined by the gradient slider that appears when you select this option. |
Gradient Slider |
Determines the specular color value along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. The gradient slider options are the same as described for the Diffuse Gradient parameter above. |
Specular Decay |
Controls the size and falloff of the specular highlights. This option is unavailable if you select the Use Specular Gradient option. |
Specular Decay Root / Tip |
When you select the Use Specular Gradient option, you can also set the location (root and tip) and value of the specular decay along the length of the hair strand using its own gradient slider. The gradient is used as a weighting factor to modulate the hair root and hair tip shininess. |
Enable |
Enables calculation of transparency values. |
Overall Transparency |
The transparency value of the whole hair strand. A value of 0 is completely opaque and 1 is completely transparent when Length and Cross are not active. When either Length or Cross are active, a value of 0 is no transparency and 1 is 100% of either Length of Cross (whichever is active). |
Length
Enable |
Enables the calculation of transparency values along only the length of the hair strand. |
Gradient Slider |
The gradient slider determines the transparency value along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. A value of 0 is completely opaque and 1 is completely transparent. The gradient slider options are the same as described for the Diffuse Gradient parameter above. |
Cross
Enable |
Enables the calculation of transparency values across the hair strand. |
Gradient Slider |
The gradient slider determines the transparency value across the hair strand. The left end of the slider represents the hair strand edges (rim) and the right end represents the hair strand center (core). A value of 0 is completely opaque and 1 is completely transparent. The gradient slider options are the same as described for the Diffuse Gradient parameter above. |
Global Illumination / Caustics / Final Gathering
Radiance |
Used to control the color and intensity (strength) of any indirect lighting effect (global illumination, caustics, or final gathering) over the object’s surface. Also, you can texture this parameter in order to reveal indirect illumination on a given location on the hair. |
Translucency
Translucency allows light to partially or diffusely pass through the hair strands. The Hair Geo shader computes the illumination from both sides of the hair and adds the result. This lets you create a glow or rim lighting effect on hair, which can increase the realism of hair, especially when the hair is white or light-colored or in a brightly lit environment.
You can set the overall translucency for the whole hair strand or you can use the gradient slider to have varying translucency values along the hair strand. For example, hair is usually more translucent at the tips but less so at the roots.
Enable |
Activates the calculation of translucency on the hair. |
Translucency |
If you select Enable, you can use this slider to set the hair’s overall translucency level. A value of 0 is no translucency, and 1 is full translucency. |
Translucency Gradient |
Activates translucency using the gradient controls. The gradient slider determines the translucency value along the hair strand’s length. The left end of the slider represents the hair strand root and the right end represents the hair strand tip. A value of 0 is completely opaque and 1 is completely translucent. The gradient slider options are the same as described for the Diffuse Gradient parameter above. |
Incandescence
Adds an emissive color to the hair strand on top of the hair shading. This lets you create glow effects and allows the hair to appear more “tubular” when a light color is used on the inner core of the hair strand and a darker color is used on the edges (rim) of the strand.
Inner |
|
Enable |
Uses the incandescent color settings for the hair as defined with the color controls. This is applied to the inner core of the hair strand. |
Color controls |
Controls the R, G, B, and alpha values for the emissive color applied to the inner core. |
Intensity |
The intensity of the incandescent color values. |
Rim
Enable |
Uses the incandescent color settings for the hair as defined with the color controls. This is applied to the edges or rim of the hair strand. |
Color controls |
Controls the R, G, B, and alpha values for the emissive color applied to the hair strand edges. |
Intensity |
The intensity of the incandescent color values. |
This surface shader can be connected directly to the Surface and Shadow inputs of the Material node of a hair object. You can use textures to control color inputs (such as Diffuse or Ambient Color). Alternatively, you can attach an illumination shader such as Phong to the Hair Geo Shading’s material input to replace the shader’s own illumination calculations.
You could use an image shader or procedural shader to “texture” the hair. Or use the Scalar State shader to extract the hair length/crosswise information, which can then be regrouped into a vector (Scalars2Vector shader). This vector can then be used to lookup a procedural noise or image.
SOFTIMAGE|XSI v.6.01