Graphics Reference
In-Depth Information
tached to the surface, or from random values of the individual particles. Before coloring the grass (or fur, in
this case), the elements need to be generated.
To add fur to an existing material, choose Fur Material from the Special section of the Add Layer drop-
down menu in the Shader Tree. You will need to adjust the default settings significantly to create a proper
grass material. Make the following changes to adjust the fur to make it look like grass:
1.
Set the Render Density to 250%.
2.
Decrease the Spacing to 3 mm. This places the grass blades 3 mm apart, but since the density is at
250%, there will be 2.5 blades in that space.
3.
Set the Length to 50 mm. This makes grass blades that are about 2 inches tall.
4.
Set the Width to 50%. This will create blades that are half of the Spacing distance in width (about
1.5 mm).
5.
Set the Taper to 75%. This will make the tip of the blades one-quarter the width of the base.
6.
Change the Type from Cylinders to Strips. This both simplifies the geometry and makes particles
that are more similar to grass in appearance.
These settings on a simple terrain will look like
Figure 11-26
.
Figure 11-26:
Grass particles with no color attached
As previously stated, the color of the fur can be controlled from the base material, in which all of the
strands are a single color. However, subtle and realistic shading comes from image maps or gradients. To
attach random color to the individual blades, create a gradient layer (from the Processing section in the Add
Layer menu) and then make the following changes:
1.
In the Input Parameter menu, choose Sample Parameters
⇒
Particle ID.
2.
Click Edit Gradient.
3.
Set the existing gradient key to the desired base green color.
4.
Create an additional key at 1.0 along the horizontal axis and set the color to an alternate green color.
(I chose a darker, more yellow color for the secondary color.)
