KNOW THE ARTIFICIAL INTELLIGENCE MODEL BEHIND THE NEW GAME ” THE LAST OF US 2″

SO FINALLY AFTER BEING DELAYED DUE TO THE CORONA VIRUS PANDEMIC THE LAST OF US 2 IS OUT !! THERE HAS BEEN MASSIVE USE OF ” AI” IN BUILDING THIS GAME TO MAKE THE PLAYERS FEEL ” AS REAL AS IT GETS!!!”.

“In the previous chapter, we discussed the overall design philosophy and the AI techniques behind the Infected. In this chapter, we will discuss a question that relates to the human opponents in The Last of Us. When we started prototyping the human enemy AI, we began with this question: How do we make the player believe that their enemies are real enough that they feel bad about killing them? Answering that one question drove the entire design of the enemy AI.

Answering that question required more than just hiring the best voice actors, the best modelers, and the best animators, although it did require all of those things. It also required solving an AI problem. Because if we couldn’t make the player believe that these roving bands of survivors were thinking and acting together like real people, then no amount of perfectly presented mocap was going to prevent the player from being pulled out of the game whenever an NPC took cover on the wrong side of a doorway or walked in front of his friend’s line of fire.”

TRAVIS MCINTOSH ,CHAPTER 34 ,GAME AI PRO ,VOLUME 2

THE ABOVE QUOTATION AND OTHER CHAPTERS OF THE GAME AI PRO ALSO REFER TO USE OF AI IN THE GAMES .BUT IS THE TERM “ARTIFICIAL INTELLIGENCE” ACTUALLY IN PLAY HERE. THIS MIGHT DISHEARTEN YOU AS GAMER WHO THOUGHT ALL ABOUT THOSE FANCY DREAMS ABOUT PLAYING IN AN ENVIRONMENT WHICH USES AI , AND SEEMS ALIVE ,BUT THE TRUTH IS THE TERM AI IN GAMES IS ACTUALLY JUST A MODEL THAT SELECTS THE BEST ALTERNATIVE OF ALL POSSIBLE SOLUTIONS IN SOME CASES AND IN SOME CASES IT JUST MAKES RANDOM CALLS . THIS OPTIMISATION OF SELECTING THE PROCESS GIVES THE ILLUSION OF “INTELLIGENCE” .

IN SOME CASES A CORRECT STEP TAKEN BY A NPC (NON PLAYABLE CHARACTER ) LIKE AN INFECTED HUMAN IN THIS CASE LEADS TO REDUCTION IN ALL POSSIBLE DECISIONS THAT IT CAN TAKE INTO A RATHER REDUCED AND REFINED SET OF DECISIONS AND IT GOES ON , SOMEWHAT LIKE A BINARY SEARCH , IF IT FINDS THAT YOU ARE PRESENT IN THE LEFT HALF , THE ALGORITHM ELIMINATES THE OTHER HALF IN THE NEXT TRIAL . SUCH ALGORITHMS GIVE A FALSE SENSE OF LEARNING . WHETHER THE USAGE OF SUCH TERMS IS A RESULT OF A SIMPLE TREND OR PART OF A MARKETING STRATEGY IS OPEN TO DEBATE . RIGHT NOW LETS FOCUS ON WHAT IS THE ACTUAL WORKING MECHANISM.

SO WHAT ARE THESE ALGORITHMS

SIGHT CONE OR SHAPES

SO HOW DOES A HUMAN OR AN INFECTED ONE GETS TO KNOW ABOUT YOUR PRESENCE . IN THE GAME THEIR ARE FOUR TYPES OF ENEMIES , THE INFECTED , HUMANS , STALKERS AND BLOATERS NAMELY. EACH HAVE DIFFERENT SET OF CAPABILITIES , HERE WE TALK OF VISION . OUT OF THE FOUR HUMANS AND STALKERS ARE THE ONLY TWO PROVIDED WITH VISION ABILITIES . SO HOW DO THEY SEE YOU?

REMEMBER EVERYTHING IS JUST JUST A 2-D GRID FOR THE COMPUTER , AND FOR THE GAME PROGRAM EVERYONE JUST A LOCATION , THE ENTITY AT A CERTAIN LOCATION HAS SOME ABILITIES , SIGHT BEING ONE ,AND IN THE LAST OF US 2 , THE ” SIGHT” IS A REGION , A GEOMETRICAL FIGURE , IF YOU FALL WITHIN THE REGION , THE ENEMY CAN “SEE YOU “. OR RATHER PUTTING IT IN A PROGRAM: KEEP ” SEARCHING ” FOR THE PLAYER MEANS TO CALCULATE WHETHER THE LOCATION OF THE PLAYER FALLS WITHIN THE SIGHT SHAPE FOR THE CURRENT FACE DIRECTION OF THE ENEMY . IF YES , THE ENEMY COMMUNICATES THIS TO THE NEARBY ENEMIES BY CREATING A BROADCAST PROCESS AND ITSELF REQUESTS TO CALL A FUNCTION THAT ALLOWS IT TO APPROACH THE PLAYER .

WHILE PLAYER NOT DEAD:

IF PLAYER LOCATION IN SIGHT CONE/POLYGON :

CALL (FOLLOW SHORTEST PATH TOWARDS PLAYER)

ELSE :

RANDOMLY ROTATE THE SIGHT CONE:

EARLIER , SIGHT “CONES ” WHERE USED AS CAN BE SEEN IN THE FIRST FIGURE . BUT SUCH SIGHT CONES HAD A MAJOR DEMERIT . THE SHAPE OF THE SIGHT SPACE MAKES A DISTANT PLAYER VISIBLE . ON THE OTHER HAND , THE PLAYER STANDS TOO CLOSE TO THE ENEMY BUT IS NOT BEING “VIEWED” . THIS PROBLEM WAS ADDRESSED BY THE GAMES DESIGNERS AND THEY CAME UP WITH BETTER SOLUTIONS OF SIGHT SHAPES . THE FIGURE SHOWS ONE SUCH COMPLEX SIGHT SHAPE .

“HEARING AND FINDING YOU “

SIMILARLY FOR THE INFECTED AND BLOATERS EVERY TIME YOU CREATE A SOUND IT CREATES AN INTERRUPT IN THE CODE CAUSING A BROADCAST OF A SIGNAL IN A RADIUS OF CIRCLE R . THIS RADIUS DEPENDS ON THE INTENSITY OF THE SOUND YOU MADE , OR HOW FAST YOU ARE RUNNING . WHEN THE ENEMIES ARE SEARCHING FOR YOU EVERYONE IS TRYING TO GET YOU EITHER IN THEIR SIGHT OR AUDIO RANGE . ONCE YOU ARE IN THERE THE ENEMY CALLS RANDOMLY ONE OF THE COMBAT FUNCTIONS ONCE IT HAS APPROACHED NEAR YOU , THIS APPROACHING IS DONE USING SITEMAPS AND EXPOSURE MAPS .

THE BLACK BOXES ARE THE WALLS OR HOUSES AND THE SHADED AREAS ARE THE REGIONS THAT ARE OUT OF SIGHT OF THE PLAYER . THIS IS WHAT THE GAME ACTS ON

WHAT HAPPENS ONCE YOU ARE FOUND?

ONCE FOUND THE NPC SEARCHES FOR THE MINIMUM DISTANCE FROM THE PLAYER .SO BASICALLY EVERYTHING IS A COMPLEX IF ELSE INSTRUCTION SET AND NOT MUCH OF AN “ARTIFICIAL INTELLIGENCE” BUT DON’T LET THIS FACT COME BETWEEN YOU AND AN AWESOME ADVENTURE AHEAD!!! GO AND TAKE SOME HEADSHOTS!!! AND IF YOU WANT TO SEE HOW A DEEP LEARNING ARTIFICIAL INTELLIGENCE CAN ACTUALLY BE INCORPORATED IN A GAME CLICK HERE. ACTUAL IMPLEMENTATION OF AI WOULD MEAN THAT THE ENEMIES WOULD BE CUSTOMISABLE ACCORDING TO THE SPECIFIC PLAYER . SUPPOSE YOU LOG IN AS A PARTICULAR PLAYER .

1. EACH ENEMY TYPE WOULD HAVE A “BRAIN” .
2. EACH BRAIN IS A NEURAL NETWORK . THE WEIGHTS OF THE NEURAL NETWORKS WILL BE UPDATED AS YOU PLAY .
3. THIS WILL DEPEND EXACTLY ON HOW GOOD A PLAYER YOU ARE , WHICH WEAPON YOU USE THE MOST , HOW DIFFICULT IS TO SPOT YOU , AND SO ON .
4. THEREFORE EACH TIME YOU LOG IN , THE WEIGHTS OF THE LAST GAME YOU PLAYED ARE APPLIED AND HENCE THE ENEMIES WILL START OF “KNOWING ” WHAT SORT OF PLAYER YOU ARE !!!!