|
[In this reprinted #altdevblogaday opinion piece, Visual Outbreak creative director Alex Nortonshares how his team set out to create an infinite, procedurally generated game world .] Procedural generation is definitely in vogue, and I personally havebelieved that it is the way forward in video gaming for many yearsnow. Using procedural generation in games is nothing new of course,as fans of games such as Elite or The Sentinel will know that we've been seeing it in games for a good 25 years. Older titles made good use of it due to the memory constraints ofthe hardware of the time. It was simply more efficient to havegenerated levels rather than hand -rafted ones, but that is noexcuse for games not to make better use of it now that we havebetter specced hardware. Fans of the RPG genre will no doubt remember The Elder Scrolls II: Daggerfall , which had one of the largest in-game worlds ever seen, and stillto this day tramples almost every RPG made in terms of world size.I recall reading somewhere that the in-game world of Daggerfall was equal to twice the landmass of the British Isles. That is a heck of a lot of world to explore, and – from agame design perspective – a nightmare to recreate by hand.Through clever use of procedural generation, however, it is easilypossible, which is what Bethesda Softworks did with Daggerfall . The settlements and towns were hand-crafted, with the wildernessin between being generated by the game. But why stop there? Why have world borders at all? Proceduralgeneration code hasn't changed much in the last 25 years. Peopleare still stuck using fractals and diamonds and blobs to doeverything, which becomes repetitive and quite simply looks like procedurally generated content. To any programmer looking atit, it virtually smells of procedural generation. On top of all this, if you get it wrong, it will end up VERY wrong.The indie crowd seems to do it best, with titles like Dwarf Fortress generating MASSIVE worlds with lush histories and more world thanyou could ever hope to explore. But still, they aren't pushing theenvelope. My aim was to fix that by making it work. An infinite game worldshould be possible, and indeed it is. The idea Just over two years ago I began assembling a team to make the firsttruly infinite, fully 3D fantasy RPG, entitled Malevolence: The Sword of Ahkranox. It was to be played in a style similar to the classic grid-based,first person RPGs of the late '80s and early '90s such as Might & Magic, Eye of the Beholder and Dungeon Master , but set in a literally infinite world. We had originally thought to make it a planet-sized world, but inthe end decided on the story being that the game's world was beingcreated within the imagination of a sentient sword, which would actas a way to "explain" the infinity of it. After much experimentation and very complex math, we got it working, but allin raw data. Nothing really playable. But we had in front of us aninfinite world filled with infinite dungeons and infinite citiesfilled with infinite NPCs. We then worked to get a game working insuch a world (some of the efforts of which, you may have read aboutin my last post ). Now, just to confirm, this world wasn't being randomly generated.It was both infinite AND persistent. Without going into too muchdetail, this is achieved by making the world dynamically affectedby the passing of time. Every part of the world is identified aseither affected by time or timeless. The lay of the land with itshills and caverns… That's all timeless, and never changes. Because those parts never change and cannot be affected by theplayer, they only need to be loaded into memory when the player cansee them (or if they are needed to generate quest information,etc). However, if an object is affected by time (for example, thecontents of a chest), then they have a time coefficient applied tothe procedural algorithm that generates them. This means that a chest in a dungeon, for example, will havedifferent items in it depending on WHEN the player opens the chest.If the player was the clear out that chest, that act is stored in adatabase of player changes, but then re-set when a certain amountof time has passed. This ensures that the database of playerchanges to the world never exceeds a certain size (which isestimated to be around 250mb at the very most, but morerealistically around 50mb) This generation accounts for almost everything in the game. Spellcreation, item creation, weapon creation, potion creation, NPCdialogue system, even the spell effects that happen on the screen. Due to this, the world that the player explores will beever-changing and infinite. They won't keep finding the same oldweapons or items, there will be no end to the number of spells theycan find or use, they won't even keep having the same conversationswith NPCs. This is necessary to keep a player interested for longenough in an infinite world. Public acceptance Back when the game Elite was first being worked on, it was planned to have around 282 trillion galaxies with around 256 star systems in each one, but theirpublisher, Firebird, were worried that such a large in-gameuniverse would be intimidating to players and put them off. I haveto say I had wondered at that, and was interested to see how thepublic would react to an even bigger in-game world. I was surprised at the results. We've been quite public with our development process for the gameso far and generated a small cult following on communities such as IndieDB , but very few people seem to quite grasp the scale of an infiniteworld, despite our thorough descriptions of it. We had put uprenders of the world generation data, showing just a tiny fractionof the world: And then, we showed them this: That inland sea is around the size of the entire in-game world of Skyrim . Funnily enough, the largest response we got from this informationwas disbelief. Many called us liars and that it simply wasn'tpossible. Others began to believe that the world size of Malevolence was the entire above image, rather than infinite. Only about 20percent of people really understood . So, from a marketing perspective, it's been a bit of a nightmare tohave an infinite world. We've even had many suggest that Malevolence is just a rip-off of Legend of Grimrock , despite the fact that Malevolence was started about a year before. But that's always going tohappen, no matter what the game. What happens upon release willhappen, and that's just how the cookie crumbles with gamedevelopment. Funnily enough, that hasn't been the hardest bit. The hardest bithas been the math involved in making a world like this one. The Math Being infinite, procedural AND persistent, most of the mathematicsbehind Malevolence is theoretical math – that is, mathematicswith few or no fixed/known values acting in a volatile space. Butwe've broken the world creation down into multiple layers. The first layer is the one you saw above. A large world segment isgenerated which covers an area of about 400x400km. This is the onlylayer of the game that uses a standardised procedural generationsystem ( perlin noise ) That is then broken down into chunks that are around 3x3km,calculating the biome information within that area, like so: In the end, all of these steps need to be completed when each newworld segment is generated in order to turn the raw data into this: That is just for the overworld. Every world segment that is VISIBLEto the player (as in the view above) is given a unique code,generated by the procedural algorithm. If there is a dungeonentrance in that segment, the dungeon is generated using thisunique code, ensuring that every time the player returns to thatspot, the same dungeon will be there: This same method is used for town generation, graveyards, ruins oranything else that the player may encounter. And this goes onforever. If a player was to turn off collision and hold down the'move forward' button, it would take them just under three weeks towalk from one end of a world segment to another, and then theywould simply move to a new world segment seamlessly, and thenanother, forever. The biggest question we have been given is how we have dealt withthe data type limitations on player co-ordinates, but unfortunatelywe can't give away all our secrets :) But I can tell you that Malevolence doesn't sufferfrom the Minecraft world-edge issue , it just keeps going on and on. Conclusion Using procedural generation in your game can be a rewardingexperience, but definitely don't rush into it. It takes goodplanning, clever usage and most of all it needs to feel seamless,otherwise the public simply won't accept it. If you'd like to read more about Malevolence: The Sword of Ahkranox , you can check out these links: [This piece was reprinted from #AltDevBlogADay , a shared blog initiative started by @mike_acton devoted to giving game developers of all disciplines a place tomotivate each other to write regularly about their personal gamedevelopment passions.] Related news: In-depth: Software rasterizer and interpolating in screen space Opinion: Once upon a time... In-depth: Functional programming in C++. We are high quality suppliers, our products such as China 7 MID UMPC Tablet PC , Slate 8 Inch Android Touch Tablet for oversee buyer. To know more, please visits Apple Accessory Kit.
Related Articles -
China 7 MID UMPC Tablet PC, Slate 8 Inch Android Touch Tablet,
|
