October, 2006
So let's start out with a little scene. In the scene we have a cloud formation. I want to use an opacity mask on it.

With the cloud selected we can see it in Transparency.
Keeping the cloud selected, click on the arrow and choose Make Opacity Mask.

Click on the black square.
Choose a white to black gradient.
Create a rectangle around the cloud. The gradient will automatically be applied.
And now we have a more interesting looking cloud. Try applying different gradients to the rectangle.

Copyright (c) 2006, Jacquelin Vanderwood, All Rights Reserved