Are you tired of getting worst by the Covenant ? Learn how they think from the man who created the hokey intelligence for " Halo 2 . " In this exclusive Stuffo interview , Chris Butcher of Bungie Studios crystalize us .
11/17/04
So here I am … surrounded by pizza pie boxes , soft taco wrappers , and soda cans and controller . I ’m shopworn , and I reek spoiled . I ’ve finally thump " Halo 2 . " I ’ve been ambushed , sniped , flush out , cornered and just plainly beat down by the Covenant more time than I care to recall . In both " Halo " and " Halo 2 , " the foeman ’s battlefield savvy is one of the most impressive vista of the game . The foeman are so much more than just an attack of cannon fodder . This is not your daddy ’s shooter . If you reckon that a quick induction finger is go bad to let you cover through the Covenant in " Halo 2 , " then there is a body bag with your name on it .
The foe characters in " Halo , " as with all video games , are driven by contrived intelligence agency or AI . The complexity of theAIcan often make or check a game ’s level of fun , realism and replay time value . Halo is at the top of list when it comes to AI . The enemies respond , reply and conform to the actor like real combatants on a battleground .
If you ’re stunned by just how " dirty " the Covenant ’s " unclean pool " can get in the rut of battle , then you will be interested to hear what Chris Butcher had to say about the stilted intelligence of " Halo 2 . " Chris is one of four Engineering steer at Bungie Studios , who are each responsible for certain sections of Halo ’s initiation . Chris created the AI for the original " Halo " and suffer to expand his piece of work in " Halo 2 . " Stuffo get a chance to sit down with Chris a few Day before " Halo 2 " launch and talk about the artificial intelligence of " Halo 2 . "
The Basics
" I write the hokey intelligence for Halo 1 , " Chris explain . " Basically , it is a very specialized eccentric of intelligence . There was a custom piece of code for each type . " In " Halo 2 , " Chris broadened the AI he build for the first game . The first thing to understand about the AI characters in Halo is this : " The AI lives in a simulated existence . "
Most first mortal shooter game , such as Quake or Unreal , are built on a graphical engine . The thespian is fundamentally a stationary " camera , " and the engine creates the maven of affect through a reality by render graphics that create that burden . Halo is unlike , Chris explains . " Halo is a pretence engine . The engine create the world , then puts the player and the AI in it … [ The ] fictional character and their code are insulate from the world . "
Each character is write to do sure affair , but despite their item-by-item roles , they all function in the same elbow room . It breaks down like this :
" That all works through the same capabilities the player has , " Chris explain . This is a key point in how the Halo AI work : Because the character are forced to perceive the world around them , they are , in many fashion , specify like the player by their sense – in their overall cognisance of what is going on around them . This restriction creates more lifelike behavior for the AI characters , as they can be surprised , make mistakes and decisions based on their perceptions of what ’s go on around them . As Chris puts it , " there is really very little departure between a player and an stilted news character in Halo . "
AI Perception
Chris goes on :
Chris continues :
The Decision Making
The AI in Halo each take turn " conceive " . These turns happen very quick , which gives the impression that each AI is constantly thinking . When it is its turn , each AI take in decision based on the data point they have treat . This is the AI conduct system . Chris explain :
The four province of the combat cycle are :
That ’s the decisiveness making . Behind it all is a basic scrap cycle of seeing enemies , engaging foeman retreat and go back into another fighting body politic . Now those are all combat - specific behaviour because … our AI does n’t wassail , it does n’t deplete , it does n’t slumber . All it really does is suffer around and then fight when enemy are nearby , but we seek to make those behaviors be as aliveness - like as possible . "
Pathfinding
Chris works with the grade designers to analyze each point in the allowable area for the AI . In a way , the thinking is done for them . Each point is assign a value , based on its characteristics in the space . For example , a high smear may be a near location if you are on the offense but not so good if you are being attacked . A spot behind a wall may be a good shoes to hide , but not to flash . The AI know these values and picks the location that offers the value it needs for the current situation .
The veridical challenge of pathfinding is getting to that dot in a style that cause sense . Chris elaborates :
to create even more pragmatism in how AI interact with objects in the world , the team employ animation to polish out the look of the pathfinding . " We also mark objects with liveliness points , " Chris explain . " A crate may have a tag that recite the AI , ' you’re able to jump on top of this if you need to . ' So when pathfinding the AI can make up one’s mind to make a path over tagged objects . In armed combat , if the AI knows an foe is hiding behind that tagged object , they may choose to jump on top of it and say something scary , or if they have lose flock of the enemy they may make up one’s mind to parachute up on an object to get a better look . "
Object tags are also used to keep the AI aware of variety in their environments and point places that an AI can use as cover . But if these top physical object are destroyed or moved , the shred convert . This is how the AI sleep with they can no longer seek blanket at that point in blank . The covering tag is tie to the target , not the space .
Working Together
" Halo 1 " offered players a level of a AI coordination and cooperation rarely seen in FPS game . By create a serial publication of construct - in reply in each individual AI , the creators made the AI look to be working together . Chris explains , " one of the most interesting affair about Halo is that we have a lot of cock to make the AI work together as a coordinate force … [ The AI ] make item-by-item decisions based on what ’s happening around them with their champion . For model , a Grunt would make the single decision , ' The Elite I was just with got killed . So I am going to draw by . ' "
The Grunts are programmed to always respond in that way . What appears to the histrion as an emotional or tactical response is , in fact , a childlike " if / then " program line .
AI were also issued command to move individually with guidelines that made them appear as if they were a team . Chris used the Marines as an example : " ' I like to support with my Quaker , but not too close . ' That is how the Marines work . The Marines tend to move together as a whole but they wo n’t stand in each others field of flame . "
But that was the first Halo . " In ' Halo 2 , ' we have new tools for them to forge together , " Chris explicate . His squad add a joint behavior system to the AI that allows them to work together on much more complicated task . " The AI will say , ' I ’m consider this joint behavior , and I acknowledge there are masses around me who are my friends . ' So they post a request to the other AI to say , ' I would like to do this behaviour with you . Will you consent it ? ' and the other AIs , when it is their twist to intend , will either swallow it or reject it and enjoin the originator . We used these fresh developments for various subtle and obvious advance . The most obvious is the characters verbalise to each other . The AI posts a joint behavior , ' I detect both of us are appear for the same cat . I need to tell you something about him and I want you to respond to me . ' or , ' We ’re both looking for the same guy cable . get ’s knead together to find him so that we can leap out out and storm him together . ' "
mystify into a fomite is another group behavior . If an AI can see a moving vehicle , it cam post a postulation to the AI push back that fomite , enquire for a drive . The AI number one wood , if he accepts the post , will blockade , sprain around and piece him up .
And the dialog is n’t just for flavor , Chris explains . " The talking is important because the AIs behavior and communication would n’t be obvious to the player without the AI saying something and declare their motive to the player . "
The Uncanny Valley
As the interview start out to wind down , Chris and I discussed some of the challenges look AI .
" Are you intimate with the ' Uncanny Valley ' possibility from computing machine quicken film ? " he asked . I was n’t , so Chris explained it :
