Enabling NPCs

The past week was all about building internal systems to support NPC behavior. Much of the time was spent reading up and learning new techniques (see resource links below), then designing and figuring out how to implement in code.

What's new:

• Fact database - for storing information about the world state, quest progress, NPC knowledge... 
• NPC rule-based behavior - allows NPCs to execute scripted behavior and make simple decisions based on info from the fact database and/or sense perception.
• Location aware conversation selection - some conversations can be set to only/never occur at specific locations.

To do:

• Extend the rule-based decision making to conversation selection.
• Stress test the various behavioral systems to expose logic bugs, conflicts and limitations

The screenshot above shows an example of what can happen when you try to initiate a conversation with a NPC that needs to go somewhere. Normally, the NPC will stop to converse.

The following resources helped tremendously to inspire and inform the creation of these systems. My gratitude goes to these guys:

• Programming Context-Aware Dialogue in The Last of US, GDC 2014 talk by Jason Gregory of Naughty Dog (video)

• Rule Databases for Contextual Dialog and Game Logic, GDC 2012 talk by Elan Ruskin of Valve (PDF)