There are some nodes like the slot and anim offset nodes which have the pin for base pose
What are they used for? for example if I use an aim offset I use a blend by bone layer to apply aim offset anim only to upper bones and it works fine.
However shootergame example has very complicated graph and uses things like anim montage and slots . what is the base pose pin of slot used for? After all you are playing all of it from the montage then why does it need the base pose.
Same with aim offset why would you ever need base pose?
The Base Pose is the Normal Animation you want to have on your character.
For example a Running Animation. If you want to blend a reloading animation into it, you would plug
the Running Animation into the Base Pose and the Reloading Animation in the Blend Poses 0 Slot of your Layered Blend per Bone Node.
Each layer has a Weight that goes from 0.0 to 1.0. So you could for example blend a second Animation over all others by adding for example a Jumping Animation to a new Blend Pose Pin. With the Weights you can change what Animation should be seen. With 0 at the blends, the base animation is played (running). With 1.0 in Reloading, the Reload animation would 100% overwrite the running animation.
So now you would ask “ok, but then i would have no running animation”, yes that’s true and this is where the “BONES” of the layerd blend per bone comes into play.
With the settings you can add a Bone. The Bones and its childern will be affected. So for example only the bones for the upper body, head and arms:
This is just to combine several things into one animation.
Here is a list of the docs:
Some additional uses for Montages include:
The ability to play an animation from within an AnimBlueprint’s EventGraph.
Chaining together a complex sequence of animations that you want to think of as a single animation.
Looping only a specific portion of animation or animations based on code or Blueprint script.
Handling event-based switching of multiple animations based on code or Blueprint script.
Proper handling of Root Motion for your characters.
The ability to assign complex animation sequences to named slots that can be switched between in code or Blueprints.
Precise switching between various AnimSequences based on code or Blueprint script.
(Source [Docs][2])
Also you can create Slots that limit your Animations to specific body parts. For example a sword swing can be put to the Upper Body Group, so it will only effect the upper body. Or a reload animation can be divided into Standing, Crouching and Running Groups. But you can read up all of this in the Docs i mentioned.
The Animation you want to blend the Anim Offset to. For example an Idle Animation. The Aim Offset itself is just blending between different poses of your character. Like looking up, down, left and right. You need to blend these into other animations.
You plugin the animation you want as a standard and blend the aim offset into it. What animation you want to blend it can be changed by the whole anim blueprint. Like running, crouching, idle etc.