A simple behaviour tree from my Archery Tag AI The first question I must address here: Why would anyone put a behaviour* tree on a camera?
Behaviour trees are a powerful tool that allows designers and artists to visualize logic flow. It is easier for a non-technical person to learn and interact with a visual system that describes the states, than one where they must infer the states. The quick wins of behaviour trees over Blueprint include less rules to understand, clearer visual connections and flow, and nodes can be renamed to disambiguate them from other nodes (all of which help first-time users too).
The video above is part of a playlist showing how to implement behaviour trees in Unreal, and is recommended viewing for anyone who wants to have a practical understanding of the features tested in this experiment. Note that we implement very basic triggers with behaviour trees in this experiment, however, these triggers are simple examples and might be better off implemented at the C++ level. Ideally, the process used in this experiment would be applied to empowering camera artists through control of camera behaviours in cases where performance costs are considered less important than giving artists a greater degree of autonomy.
Behaviour trees are a powerful tool that allows designers and artists to visualize logic flow. It is easier for a non-technical person to learn and interact with a visual system that describes the states, than one where they must infer the states. The quick wins of behaviour trees over Blueprint include less rules to understand, clearer visual connections and flow, and nodes can be renamed to disambiguate them from other nodes (all of which help first-time users too).
The video above is part of a playlist showing how to implement behaviour trees in Unreal, and is recommended viewing for anyone who wants to have a practical understanding of the features tested in this experiment. Note that we implement very basic triggers with behaviour trees in this experiment, however, these triggers are simple examples and might be better off implemented at the C++ level. Ideally, the process used in this experiment would be applied to empowering camera artists through control of camera behaviours in cases where performance costs are considered less important than giving artists a greater degree of autonomy.
This graph represents the triggering tools for camera artists on Prince of Persia. Click this picture to watch Jonathan Bard's GDC talk.
This experiment begins where Real Time Cameras in Unreal Editor 4 - Part 12 ends. Also in that article, I mentioned a GDC talk where Jonathan Bard from Ubisoft explains why they implemented a system like this for Prince of Persia. In that game, camera artists were given control of " thinking" for the camera using behaviour trees but camera senses and actions were implemented by engineers. My use of Unreal's Behavior Tree mimics the Decision Graph employed by camera artists for triggering behaviours, but I applied Blueprint for engineering tasks like scripting the camera.
*The answer to the second question is yes, I will insist on spelling behaviour in the Canadian/UK fashion whenever possible. I'll keep Unreal's spelling for their tools.
*The answer to the second question is yes, I will insist on spelling behaviour in the Canadian/UK fashion whenever possible. I'll keep Unreal's spelling for their tools.
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