LIKE GAMING HARDWARE, the balance of geopolitical power is always in flux. Back in 2001, when the first Operation Flashpoint* game was released, Cold War tension was still being shaken off. For that reason, its battlefields were fictional Northern European islands in the Baltic Sea where Communist hardliners threatened to overrun a small NATO garrison.
The PC-only game won many plaudits for its authenticity as a military simulator. It was also part of the first wave of first-person shooters to move beyond the run-and-gun corridor and involve the player in tactical squad-based decision making. Players quickly learned you couldn’t cross an open field with all guns blazing in a game that included real-world ballistics and one-shot kills. You wouldn’t even hear the shot that took you down, let alone see the shooter.
Throw in the ability to jump into jeeps, armored vehicles, and helicopters, and small wonder Operation Flashpoint went on to sell over a million units.
Fast-forward eight years, and the world’s focus has moved eastward, dominated more by pragmatic fears over the future supply of natural resources rather than ideology. So when oil and gas reserves are discovered on Skira, a sparsely populated Russian-owned island in the Sea of Japan, a resurgent Chinese People’s Liberation Army (PLA) is quick to take advantage of the situation. Once again acting as the world’s policeman, the U.S. Marine Corps is called into action to recapture the island.
Welcome to Operation Flashpoint: Dragon Rising.
The scale of the battlefield
“When we first considered making a sequel to Operation Flashpoint, the key things we wanted to get right were those features players had really enjoyed, such as its authenticity in terms of military hardware and enemy Artificial Intelligence (AI), a large combat area, and providing lots of units for them to interact with,” explained senior game designer Tim Browne.
Great for gamers, such a feature list created a series of conflicting requirements in terms of the title’s underlying technology. The scale of the battlefield immediately threw up difficult issues.
Loosely based on the real-world island of Kiska (located in the Aleutian chain, off the Alaska Peninsula), at 32km long by 17km wide Skira provides a huge 225km square playing area, or 500km square if you include the surrounding sea.
Skira takes players around nine hours to walk across, four hours to drive across by wheeled vehicle, or 20 minutes to fly across by helicopter. However, the inclusion of fast jets in the game’s armory, which can appear almost instantaneously, albeit not as playable items, ensures the tactical balance always rests on a knife edge.
In this way, Skira is a canvas full of opportunities for designers.
Created using a mixture of satellite imagery and creative license, its natural geography is varied with flat areas for military operations involving tanks and other armored vehicles, while a 1,000 meter-high volcano at one end creates mountainous conditions to fight through. Each mission also includes what’s referred to as an area of interest such as a fishing village, lake, or bunker to provide focus.
“We make sure we have an area of interest in each mission to keep the game exciting for the player, as well as to direct their movement through the game,” Browne said.
A thread in time saves nine
The fact that players need to be able to see what’s going on around them, up to 30km, is a real bind for programmers though.
Both in terms of CPU and GPU resource management, such a long draw distance needs to be carefully managed in order to stop the frame rate of even the most powerful PC rigs from grinding to a halt.
Operation Flashpoint uses Codemasters’ in-house EGO* Game Technology Platform. This consists of a core system, which shares common elements, and two separate versions: EGO Racing for racing games such as the DiRT * and GRiD* series, and EGO Action for first-person shooters.
The difference between the two versions is surprisingly subtle, affecting low-level systems, for example the occlusion culling system. This includes a variety of techniques ensuring that pixels hidden behind other pixels in terms of the camera viewpoint aren’t rendered. As such overdraw can include dozens of pixel layers, this has a significant benefit on performance.
Because the racing games are track-based, the EGO Racing engine utilizes an offline process that creates a pre-computed table of which objects can be visible at any point of the track. This greatly reduces the in-game processor workload.
In Operation Flashpoint, the player can be anywhere and looking anywhere in the environment. This means what’s visible has to be worked out in real-time: a much more complex and processor-intensive situation.
Weapons of War
One of the most important aspects of Operation Flashpoint* in terms of its verisimilitude is the accurate modeling of the military hardware operated by the U.S. Marine Corp and the PLA. These range from ensuring the look, operation, and ballistics of basic infantry weapons, such as the M249 light machine gun, the M107 Barrett anti-matériel sniper rifle, and the Chinese Type 2004 RPG, through to the full range of armored vehicles, helicopters, and light patrol boats. Players can play in the various roles enabled by such vehicles, including commanders, gunners and drivers, pilots, copilots, and door gunners.
These vehicles are also correctly modeled in terms of their physical properties with the Havok physics engine used to set up vehicle dynamics for the different wheeled and tracked configurations. Even aerodynamics, such as the ground effect that sees a cushion of air providing additional lift when helicopters hover near the ground, are included.
“EGEGO provides us with a lot of flexibility when it comes to threading and this has been adapted to support open-world shooters such as Operation Flashpoint,” explained Graham Watson, who, in addition to being EGO engine’s group lead, optimized the PC version.
“To enable this, we spent a lot of time working on threading and parallelizing features to take advantage of multi-cores. This hadn’t previously been an issue for us, but in this case the draw distance was a big bottleneck,” he added.
Particular systems that took advantage of this work were the visibility system and the grass renderer. Wherever you look in Operation Flashpoint, you can see grass; so finding a way of dealing with this in a highly efficient manner was a necessity.
In more general terms, however, as a cross-platform game much of the game’s functionality is controlled by what Codemasters calls EGO’s multi-core aware task-based system.
This creates a fixed number of threads based on the number of cores available on the hardware on which the game is running. There are dedicated threads to handle fixed jobs such as feeding the graphics engine and for processing critical game logic. Whatever remains is handed over to the task manager, which organizes how secondary processes such as high-end graphics and the particle effects are dealt with.
“We have two main threads—update and render—and a set of worker or job threads,” said Watson. “These jobs threads do a lot of the heavy lifting for other systems such as physics, animation, streaming, and render visibility, to name a few. We have a data-driven worker map system that reads in a pre-defined XML file and describes how the different systems will be mapped to the hardware threads. During the optimization phase we adjust these mappings to enable the best performance for each core configuration.”
Obviously, the more cores that are available, the higher the quality of the game experience. On the PC, Operation Flashpoint scales from its minimum specification of a dual-core 2.4 GHz system with 1 GB of memory and a 256 MB graphics card, to a recommended specification of a quad-core system with 2 GB of memory and a 512 MB graphics card. Providing more cores and making more threads available means the performance can be fully ramped up in terms of graphic quality such as texture resolution and the quality of the particle effects.
More good news for PC owners comes in the form of the Mission Editor, which is exclusive to the PC release. This allows players to create, share, and play their own missions using tools similar to those used by the game’s development team.
“Obviously we want to reach the widest possible audience but at the same time we need to keep the quality of the game high for everyone,” said Bryan Marshall, Codemasters’ chief technical officer, concerning the issue of supporting the widest range of PC hardware. With the release of the Intel® Core™ i7 processor for mobile users, Operation Flashpoint can be played anywhere, anytime with unparalleled mobile gameplay.
“We offer graphical scaling options in the main menu to give users a choice of end-visual fidelity. Frame rate is the main item affected by CPU configuration since we don’t want to turn off any gameplay features. Playing Operation Flashpoint on a top-end PC, such as one with an Intel® Core™ i7 processor, whether in a desktop or a mobile system, allows us to double the texture resolution compared to the consoles and to run at a 60-Hz-plus frame rate—making it a great experience for our players.”
“In addition, we’ve worked closely with Intel for a long time, so we have a lot of knowledge within Codemasters about how to make the most of development for Intel® platforms,” he added. “We are in regular contact with Intel engineers who help us profile builds using tools such as the Intel® VTune™ Performance Analyzer.”
“Another toolset we started using on Operation Flashpoint is the Intel® Graphics Performance Analyzers. During our last profiling session with this toolset, we isolated a stall that was costing between two to six milliseconds a frame, or about 10 –15 frames per second, depending on resolution. It’s extremely useful to be able to hook into that experience, as well as gain insight into Intel’s longer term roadmap, so we can prepare our EGO game technology platform for the road ahead.”
Squad to attention
While the scale of Operation Flashpoint’s battlefield creates a problem for its programmers, at least it’s a problem that operates within well-behaved limits. Landscape geometry and buildings are fixed in place, as are the dimensions of the island.
This alone wouldn’t make for a very interesting game however. A great game demands a realistic enemy to fight against. In fact, it demands a lot of realistic enemies to fight against.
“A core part of the Operation Flashpoint experience is large battles set over large areas, meaning the game engine has to support a large variety and number of soldiers and vehicles on screen at any time,” said Tim Browne.
Even the game’s most basic level, the player is never alone as he or she acts as the leader of a Marine fire team, consisting of the player and three other soldiers.
With the release of the Intel® Core™ i7 processor for mobile users, Operation Flashpoint can be played anywhere, anytime with unparalleled gameplay performance.”
—Bryan Marshall, Codemasters’ Chief Technical Officer
In the cooperative mode, the fire teams can be controlled by other human players, but more generally are run by a combination of their AI and direct commands from the player. The latter is handled using a pre-set menu system in which you can change formation, the rules of engagement, and direct moves, such as flanking and assaulting enemy positions and clearing buildings.
“The fire team typically operates as part of a larger squad, with the player given a particular objective or target to seek out on the battlefield, while the rest of the squad goes about their objectives,” said Browne.
The online multiplayer game mode enables players to be more flexible, choosing to be an individual soldier, lead a fire team, or take control of the entire squad of up to five fire teams. There are also plenty of specific roles, ranging from riflemen and grenadiers to medics, engineers, snipers, and armored vehicle and helicopter crewmen.
CODEMASTERS
As the oldest major UK developer and publisher still in operation, founded by brothers Richard and David Darling with the help of father Jim in 1985, Codemasters has long traded on its technical expertise across multiple platforms. From the days of quirky yet seminal pre-PC machines such as the Sinclair Spectrum*, the BBC Microcomputer*, and the C64, and games such as the Dizzy* series, through the rise of the consoles—Micro Machines and Music—Codemasters has continued to support the PC platform.
Indeed, current games series such as racers DiRT * 2 and GRID*, action games such as Overlord* II, as well as sport title Ashes Cricket* 2009 are all being developed for the PC as well as Sony PlayStation* 3 and Microsoft Xbox* 360 consoles.
Codemasters is now majority owned by venture capital group Benchmark Capital Europe.
CHECK OUT THIS VIDEO!
Get the developer perspective and behind-the-scenes insights on the creation of
Operation Flashpoint: Dragon Rising* in this amazing new video.
Building a thinking enemy
Creating a well-balanced enemy AI system wasn’t easy, of course, and an early design decision concerning how it worked had a fundamental impact on the game’s development.
“We didn’t want our AI to cheat,” said Browne. “In some games, you can do everything right but the AI will still win at the last minute because it can do something sneaky, like being able to see through walls. Our AI operates the same way as you and uses the same information that’s available to you. Everything is done via line-of-sight calculations, so if your troops hide behind cover or use a smoke screen, it will only know the position where it saw you last.”
A laudable aim, this had significant implications for the game’s underlying technology. “The compromise is between lots of stupid units or fewer, cleverer units,” Browne said.
In order to provide the best of both worlds, the AI works off a system Browne compares to the set plays used by basketball or American football teams. In fact, these were modified from official Marine sources. Codemasters worked closely with the Corps on aspects of the game ranging from such tactics to the correct use of radio communications and what soldiers are trained to do if their gun jams.
“We don’t script our AI apart from key moments so the enemy is always considering its plays,” Browne explained. Throw into the mix a morale system that varies between different types of units and that can result in a collapse of discipline, and Codemasters is confident it’s in the sweet spot in terms of both enemy quantity and quality.
Still, such a dynamic system demands a lot of processing, so Operation Flashpoint’s coders have to be careful when prescribing how the AI system works.
“AI is a challenge especially when it comes to optimization because it always has to be running,” pointed out Graham Watson. “You can’t switch units off because the player can’t see them, for example. The point of the game is it’s a unified battlefield, so every engagement has the potential to affect every other engagement.”
Another corollary to the AI system is that the processing overhead it requires isn’t limited to working out what the enemy should do, because when battle commences, many other related tasks are required.
One of these is path-finding, which is how the AI determines how characters and vehicles get from point to point: a task made more difficult as the environment can be changed by the player’s actions.
Other tasks range from the basic graphical demands of, say, rendering an incoming troop of PLA Type 99 tanks with accompanying WZ-10 attack helicopters, to other systems such as the rigid body physics engine provided by the Intel-owned Irish middleware company Havok that underpins the in-game ballistics, to the spectacular particle effects triggered by explosions.
“The game can become CPU-bound in instances where a lot of AI units simultaneously come into view, especially when you have particle effects kick off and other environmental interaction,” said Watson.
“In particular, having characters on screen stresses animation and AI CPU calculations. For that reason, we design our systems so that loads can be spread out over frames if needed. We also use a lot of level of detail optimizations so we’re only using high-quality assets when the player can actually see them. For units in the distance, we can swap in lower-quality models and animation to maintain a constant frame rate.”
In this way, ensuring you’re playing intensive games as Operation Flashpoint on a desktop or laptop with a high-end CPU, such as an Intel Core i7 processor, is often more important than your graphics card (recommended GPU specifications assumed, of course).
Yet aside from all the fine tuning and technical deliberations, the most important outcome for the developers who have worked on Operation Flashpoint: Dragon Rising is that players experience the most realistic tactical military shooter possible.
War is hell, certainly, but played on a computer screen it can provide as much of the exhilaration as anyone could want, without having to sign up. And there’s none of the pain either, especially if you have a PC with all the settings turned up to 11.
About the Author
Jon Jordan started writing about game technology and the development process in the last century at UK magazine Edge. Since then his work has appeared in publications including Official PlayStation, 3D World, and the Financial Times, as well as on Web sites, such as Gamasutra and Pocket Gamer.
