After seeing the basic functions, we will see how to use Materials ID to control the emission zones of the hair parameters with bitmap textures...

Before starting, erase the hair created by Shag in the preceding page (object HS _ * *) also erase the entry Shag Hair in the Environment window.
Keep the hair model.

To select the sphere, change it into an Editable Polygon and select the top part.

In Surface Properties modify Mesh Edit, and assign Material ID 2.

By default the remainder of the sphere has Material ID to 1 assigned to it.

Then in Material Editor, create a Multi/Sub-Object with 3 materials.

The 1st will have the color of the sphere at the time it started, the 2nd will define the establishment of the hair and the 3rd their lengths.

Assign this material to the sphere.

The sphere must have this aspect with the two zones, corresponding to Material ID 1 and 2.

(do not to forget to get out of Sub-Object mode before assigning our new Material)

Shag Hair creates the SH_sphere01 object representing the hair.

Click on Face Level, a window appears, select By Sub-Material ID 2.

Now Shag Hair knows that it is zoned to Material ID 2 which is the zone transmitter of the hair.

Rendered with the default settings of Shag Hair.

(Sphere radius of 100 Generic units and 32 segments)

Now we can graphically define the length of the hair.

Create a texture similar to that shown above left and apply a Cylindrical UV Map to Material ID 2.
In Material Editor, and in the 2nd Material, put our texture into the Diffuse channel.
Activate show texture in the viewport.
The sphere should look like above right.

Put the following parameters into Shag Hair.
Length Multiplier, activate and put a 2 in SubMat ID.

The length of the hair is now a function of the texture contained in Material ID 2.

White, hair normal, black absence of hair.
The intermediate levels of gray would give us decreasing lengths.

Apply a rather conspicuous texture to the SH_sphere01 object to see the hair well.

Normally we would have activated SubMat ID in Density to establish the same hair. Nevertheless some hairs have appeared in the black zones (bug?).

With this texture, we controls the length of the hair.
We add it in the diffuse channel of Material ID 3. For the mapping co-ordinates, Shag will automatically use them in the zone of emission (Material ID 2).
Put these parameters into Shag Hair above right. It should be noted that this time it is the Material ID 2 (Density) which controls the establishment and Mat. ID 3 the length.

In addition to choosing the zones where the hairs appear, we control their length graphically also.

Now we will put the same color onto the hair that is on the remainder of the sphere.
Up to now it was for checking the texture and coordinates.

In Material Editor, add a sub-material by clicking on
Set Number.
To copy the same color as the ID 1 (drag and drop then Copy).

Select the sphere, and Polygon mode, select the faces having ID 2 (Select by ID) and replace them with the ID 4.
In the Perspective view, there are no more Shag hair points with Material ID 2 and the sphere has a uniform color.

In Shag Hair, click on Face Level and replace the 2 with 4, the hair will reappear in the Perspective view.

There are still some very useful functions, presented on the next page...