I often see suggestions of using Compound Paths, Subtracting Front Shape, or Knockout (or even Page Knockout!) in the creation of vector graphics, for example, in Illustrator. When should each be used?
Are there specific functions or drawbacks to any of them? I understand that Knockout is to go all the way down, but I still see people suggesting compound paths for this function, is there a reason? And what about Compound Path vs Substract Front, is there even a difference?
I think you may be confusing the definition of Compound Path vs. Subtract Front.
Compound paths are groups of vector clusters that have no connecting path. That is, they are a single object with distinct separate clusters of vector points.
When using “Subtract Front”, often times it is best to have your subtraction object be in a “Compound Path” format. The reason for this is that if you use “Subtract Front” with a group of objects (instead of a Compound Path), only the first object in the group will apply to the subtraction.
To address your question specifically, applying Compound Paths is advised when using Subtract Front, as it will ensure the object you are subtracting is complete. A knockout is preferred when you need to preserve the points in the bottom layer, since knockouts do not create or destroy vector points.
In the end, the only major difference is preservation or destruction of vector points.