Whether you are blending two or a dozen textures,
you use a shader mixing tool to blend colors, shaders, and images together.
Each texture can have its own weight and mixing mode assigned to it.
Mixer shaders are an alternative texture blending
tool to a shader’s built-in support for texture layers. Like texture
layers, they allow you to blend textures together, one after the other.
Unlike texture layers, which are blended with a shader’s parameters,
mixer shaders are used to drive shader parameters directly, using the
result of the mix.
Mixer shaders also lack the flexibility of texture
layers. For example, while you can move texture layers up and down in
the mixing order with a single command, the only way to change a mixer
shader’s mix order is by changing all of its shader connections.
For more information about working with texture layers,
see Texture Layering.
This section describes how to use a mixer shader’s
various blending options to mix textures together.
The Mix 8 Colors shader allows a
wide range of control over how your colors and/or textures are blended.
All of the SOFTIMAGE|3D blending methods are still available. See the
following table to learn how they translate.
SOFTIMAGE|3D Mode
XSI Equivalent
Without
Mix (Alpha option not checked)
Alpha
Mix (Alpha option checked)
RGB Intensity
RGB Intensity
RGB Modulate
Hide/Reveal
In XSI, the default is equivalent to SOFTIMAGE|3D’s
Alpha option.
The following images define each mixing mode and how
it reacts according to a gradient, a repetitive texture, and an image.
How the Mix 8 Colors shader reacts
to a “white-to-black” gradient and a repetitive, colored
texture.
How the Mix 8 Colors shader reacts
to a “white-to-black” gradient and a texture map.
Mix Calculates a simple average of each layer’s pixel values.
This is the default mode for the mixing shaders.
Tip: Scrub the Weight
slider for a cross-fade.
Add Compensate (Blend) Makes the brighter sections of the second layer gradually (and
proportionally) screen out the darker sections of the first layer. This
mode compensates the first layer prior to adding, so the resulting color
never exceeds 1 (100%).
Tip: You can use this
mode to blend two high-intensity images without losing detail.
Add The Add mode adds the first and second layers’ pixel values.
The result is not clipped at 1 (100%).
Add (Bound) Performs a similar calculation to the Add mode, but all values
are clipped at 1 (100%).
Hide/Reveal (Multiply) Multiplies all of the layers’ pixel values. Using a 1 (white)
Weight value, the second layer’s pure white pixels reveals the
color values of the first layer. If the Weight is set to 0 (black),
a black image is displayed. Because this mode often produces dark results,
consider the full range of the layers. Good, intense blends can be achieved
by using two light-colored sources.
Hide/Reveal Bound (Multiply) Performs a similar calculation to the Hide/Reveal (multiply),
except that all values are clipped at 1 (100%).
RGB Intensity Calculates a proportional average of each layer’s pixel
values. The average is dependent on the brightness of each layer.
Darker Sets the darkest color (between the first and second layer) as
the result color. Pixels darker than the blend color are not replaced.
Lighter Sets the brightest color (between the first and second layer)
as the result color. Pixels darker than the blend color are not replaced.
Difference Takes the brightest color (between the defined color and the
base color) and subtracts it from each of the color channel’s values.
Hard Light Causes the first layer’s bright pixels to brighten the
next layer’s light pixels. Also, the first layer’s dark
pixels dims the second layer’s darkest pixels. Visually, each
layer is pushing the other layer’s extreme pixel values; that
is, the darks become darker and the lighter parts become brighter.
Hue Offset Makes the darkest pixels of the second layer dim the gamma and
boost the contrast of the first layer. Meanwhile, the brighter pixels
of the second layer boost the gamma and dim the contrast of the first
layer. The brighter the layer, the more it offsets the first layer’s
hue. Visually, you’re controlling both the gamma and the contrast
values simultaneously on different parts of the image.
Screen Multiplies each color channel’s values with the inverse
of the defined color and the base color. The Screen function results
in a lighter color as though the original color has been faded.
Soft Light Mixes the first and second layers, then reveals the resulting
color with the brightest pixels of the second layer.
