Excuse me if this feature exists, I don't believe it does.
xLights is aware of pixels and knows how to drive them but currently it drives those pixels through the idea of models. Models are groups of pixels.
xLights makes it easy to treat my entire house as one big giant "model". That gives me tons of power and is the reason I switched to using xLights.
I can also create and control certain areas of my house by creating groups. Groups are sets of models connected together into the group and now I can make the whole group fade from red to green. Nice.
The new feature I'd like to see added to xLights would take xLights to the next level. It's the ability to create dynamic groups of pixels that are no longer tied to the old paradigm of models. I call the feature Spotlight models because that's the easiest way to think of it. Imagine an old school spotlight that you can control pointed at your house. If pointed at the center of your house the "group" would include a certain set of pixels. Point the spotlight to the left side of your house and the group changes to include a completely different set of pixels. That's the dynamic part. The group is no longer fixed, its morphing as the sequence plays. Here's how I'd want the feature to work.
1. Open the 2D Preview window.
2. Right click in 2D space and select Create Spotlight -> Star
3. A star shape appears in the view.
4. Resize, move and rotate the shape to get it the size and location you want.
That's it. Phase one, we might just stop here. We've drawn a shape and should be able to determine what pixels from what models should be included in this new "group". The key is that we no longer need to include the whole model, only certain pixels from within it.
Phase two makes it even more powerful. Imagine that we can animate this shape, say have it follow a bezier curve over time, have it rotate and resize. That gives us another giant step in power.
