Alpha Section

Alpha Maps

The alpha map works in conjunction with the color map. It uses the current texture function and blend points to create an extra channel that can be used to control all of the other surface attributes, see the Affect Attributes Section. The Alpha map can also be used to control the bump height, see the Bump Attributes Section as well as controlling the combining of two other materials when the texture is being used as a material map, see the Texture Layer Section. As with the color maps the alpha map will be affected by the current wave type selected and the state of the Do Blend check box. Examples of some simple alpha maps are shown below:

Alpha Map 1

Here a simple gradient has been set up to go from alpha being 0% to alpha being 100%. On the sample cube the alpha channel has been used to control the diffuse setting on the surface based on a fBm texture.

Alpha Map 2

Here a simple gradient has been set up to go from alpha being 0% going to 100% and back to 0%. On the sample cube the alpha channel has been used to control the diffuse setting on the surface based on a fBm texture.

Wave Type

The wave type control allows the texture function to be mapped to one of ten different wave types. By default a Sawtooth wave form is used but by selecting one of the different wave types a whole set of new pattern variations can be created. Looking at the wave types below, it can be seen that something like fBm can have considerably different appearances:

Wave Types

Cosine	SawTooth	Sine	Scallop	Smooth	Triangle
Invert	ArcTan	Exponent	Power	Round

Do Blend

The Do Blend check box controls whether the color and alpha maps are blended or use discrete steps. With the check box enabled the blends are smooth transitions for one value to the next, just like the ones shown on the Color Maps Section. When the Do Blends is switched off the transitions are discrete. It is important to note the when blending is switched off the first blend point, Blend 1, sets the point at which Color 1 transitions to Color 2. So if Blend 1 is 0% then none of Color 1 is shown as the color map transitions straight to Color 2. Some examples of the discrete blends can be seen below:

Non-Blended Color Map 1

Here a simple gradient has been set up to go from Yellow to Red. As the Do Blend check box has been disabled the color map is done using discrete steps.

Non-Blended Color Map 2

Here a simple gradient has been set up to go from Yellow to Green to Red. As the Do Blend check box has been disabled the color map is done using discrete steps.

Blend Type

The blend type setting controls how the current texture color is mixed with the underlying color when an alpha map is used in conjunction with the Affect Layer control. The Affect Layer control allows a alpha map to control the intensity of the current texture's color. By using this with a alpha map the current texture color can be faded, mixed or removed based on the texture function. By default the color is mixed with the underlying color. However, by selecting a different blend method the color can be Added, Subtracted, Multiplied, Ored, Anded and Xored with the underlying color. The strength the current texture's color based on the alpha map. If the alpha map is 0% the color is full on while at 100% the color is fully off. So for Mix mode where the alpha map is 0% the color derived for the current texture is applied full on and where the alpha map is 0% then underlying color will shown through completely. Values in between will cause a mix between the two. The other blend type work in the same way. Say the object was Blue and a linear gradient was applied with all with all its colors Red but with an alpha map that went from 0% to 100%. At 0% the gradient would trying to apply Black as the alpha would have completely turned the color off so Blue + Black is Blue. When the alpha map reached 100% the Red would be applied full on. So Blue + Red is Magenta. The final surface would then be a gradient Blue to Magenta.

Blend Types

No Affect	Mix	Add	Subtract
Multiply	And	Or	Xor
For the pictures a cube was created with a black and white striped pattern on it. A second texture was added that a linear blend with all its colors to white. A alpha map was created the went from 0% to 100% across the range of the blend. The Affect Layer check box was enabled and the different blend types were selected.

Affects Type

The affects type control changes the way the surface attributes defined by the current texture are combined with the current surface attributes. When Layer is selected then attributes will be added to the current surface attributes. This means the strongest attribute prevails. With Mix selected the attributes created by the current texture are simply mixed with the current surface attributes. Finally, if force is selected then attributes created by the current texture are applied to the object without regard to the current surface settings.

Affect Types

Base Layer	Layer	Mix	Force
Here a simple transparent/opaque stripe pattern was placed on the cube to create the base layer. The same texture was then applied, rotated, using the three affect types.