Sometimes you may come across the simple need of fading an object in or out. The first idea a new user usually gets is to use the Transparency Channel of a Material. That’s a bad choice because you’ll very likely use the material on several objects and they will all be affected then. Or your object has more than one material and so every material channel has to be manipulated. Until we don’t have support for a node based material system in Cinema 4D this isn’t the way to go. And honestly fading an object in or out shouldn’t be done by changing material attributes.
Better use the visibility option in the Display Tag. This is a much better idea but you’ll run into some unpleasant things as well.
When this object consists of overlapping geometry, it might look like this:
This might not be the eye-candy quality you are looking for. In addition to looking plain ugly in most situations rendering with using the visibility option for transparency will increase render time by the factor of 2 and more. Not only it strains your eyes, it also strains your time.
A common reply for solving the fading-issue in the forums is “do it in post”. And that is a perfectly valid way to approach this task if you have a compositing software by your site. But what if you don’t own a copy of After Effects or another costly Compositing Software? Don’t give up. With a little tweaks we make this damn display-tag to work in our favor.
1.Grab yourself a compositing-tag and throw it right on fading object. Right beside the display-tag.
2. Bring the “Exclusion” Tab of the Compositing Tag to the front and drag your fading object into the exclude-area.
3. The little icons behind the objects name look per default like this now:
What do they mean? Unfortunately you wont get any hints by hovering your mouse-arrow over these symbols. From left to right their name is:
The first 3 items in this list name render-attributes of an object. You can activate or deactivate these render attributes here. This gives you the option to i.e. deactivate the reflection of another object.
The hierarchy item in the list defines whether only the object in the list should be considered here or all his child-objects as well.
You can read the default setting as: Deactivate the refraction and reflection of the listed object and all its children for the object which carries this tag. But what we want is different. We want that our transparent object isn’t affected by it’s own transparency. Sounds weird? I agree. It’s complicated to explain only with words. When you look at the third image in this post you’ll find that the vehicle itself shines through its own transparent geometry. To avoid that apply these settings:
Be sure that the object that carries the tag is the same object as the one in the list. It reads now: Deactivate the transparency of the listed object for the object which carries the composite tag. Need a hint to learn these settings? Just click every of the first 3 icons once. Because this is the exact opposite of the default state. Enough with all the talking. Let the result speak. Hit Render! This is the resulting render:
Now you can start fading objects in and out directly in Cinema 4D. Of course this works with stills as well as with animation. Isn’t that great?
If you have any ideas to improve this tutorial, or problems to get the right results make use of the comment feature.