Andy Mees wrote:Take a look at Chapter 143, “Combining Keys and Using Mattes.” in the Reference Manual ... page 2892 is where it gets in to adding and subtracting keys.
That is hugely important. The trick is (I almost said "the key is") to figure out a way to constrain and control the key so that only what you want to control will be affected by the key. I tend to think of a MATTE as everything "inside" the window that I'm actually keying, and a MASK (aka a garbage matte) is everything "outside" that I'm trying to avoid changing. Sometimes you need to use multiple windows, like in a case where you've got a shape around one character and another person walks in front of them. That requires animating and tracking a mask on that person, in the same node, in mask mode so that the key doesn't affect them.
There are good video tutorials that explain the basics of keying and masks in great detail: I often recommend Ripple Training, Mixing Light, and FXPHD as being great resources to anybody using Resolve, new and old. And Lowepost, TACResolve, and De-Mystify Color also have some additional training ideas that are helpful. Cullen Kelly and Darren Mostyn on YouTube have some great free tutorials as well. All of them cover keying and masks/windows in great detail.
Hey, if you think keying/masking in Resolve is difficult now, you should've seen it 20 years ago: it was a nightmare with daVinci 2K (the predecessor of Resolve). That was very tough. From 2008 on, DaVinci Resolve became much more streamlined and understandable, so what we have now in 2021 represents literally decades of thought on how to make operations like this easy and accessible, and not so cryptic and weird. Once you know what you're doing, it takes maybe 10-15 seconds to set one of these up.