Graphics Reference
In-Depth Information
Because all RGB values range from 0.0 to 1.0, multiplication can only leave a value the same or darken it.
Any pixel multiplied by a black pixel (RGB value 0, 0, 0) will result in a black pixel. Any pixel multiplied by a
white pixel (RGB value 1, 1, 1) will result in a pixel of the same color as the original pixel. A pixel multiplied
by another pixel that is neither black nor white will have its RGB values diminished according to the RGB val-
ues of the second pixel. This is why multiplication is appropriate for render passes that darken an image. The
main two render passes that do this are the Shadow pass and the Ambient Occlusion (AO) pass.
First, let's work with the Shadow pass:
1.
Add a Mix node by choosing Color > Mix from the Add (Shift+A) menu, as shown in
Figure 9-16
.
Figure 9-16
Adding a Multiply Mix node
2.
Choose Multiply from the drop-down menu, set the Fac value to
1.0
, and connect the input node's Dif-
fuse output socket and the Shadow output socket to the first and second input sockets on the Multiply
node.
3.
Send the output from the Multiply node to a Viewer node, as shown in
Figure 9-17
.
