9.5.2

840 • CHAPTER 18
MATERIAL EDITOR • 841
Premultiplied
Enable this option if you are using a texture with a premultiplied alpha channel. Certain graphics
applications only produce this type of alpha channel.
Texture, Mix Mode, Mix Strength
For details on these settings, look up ‘texture settings’ in the index.
Example
Suppose you want to place a scanned picture of a tree into a scene. First, you
should create a material, enable the Color channel, choose a picture of a tree
as the color texture and then assign this material to, perhaps, a rectangular
polygon.
If you render this scene, you should see the tree on the rectangle polygon.
However, the area around the tree is probably not transparent, but blue if the
scanned picture has a blue sky background (Figure 1).
Now edit the tree material, enable the Alpha channel, switch to the Alpha
page and load the tree texture there. Use clipping to mask out the tree. Use
the mouse to choose the color which you want to mask — in our case, the
blue sky around the tree (Figure 2). CINEMA 4D sets the color sliders to this
color and masks according to the picture. The tree is now shown without the
surrounding background (provided that you have Gouraud Shading or Quick
Shading on).
Figure 1. Figure 2. Figure 3.
You can now select a slightly different color on the Alpha page and see the
effect immediately. However, some background may be left around the
leaves, branches and the trunk. So the result is not quite right yet. For a more
accurate result, create an alpha channel in your image editor and integrate this
into the tree image; for details on how to do this, consult you image editor’s
documentation. Load this picture into the Alpha channel and enable Soft and
Image Alpha. The texture is now masked cleanly (Figure 3).