Empire: Total War Takes to the Waves

By Jon Jordan

At the start of the eighteenth century, Portsmouth, England’s harbor was the global hub of the world’s most powerful fighting force, the Royal Navy. Bristling with forts and gun emplacements, it contained squadrons of ships-of-the-line ready to sail into the Atlantic to defend the empire and in pursuit of treasure and adventure. It’s somehow appropriate then that war games developer The Creative Assembly is located a mere 40 miles up the road.

Not that the 70-strong team has had much time for days off in recent months. Empire: Total War*, the fifth game in its massively successful and critically acclaimed PC strategy franchise, has only just been released. Moving the action on from previously examined battlefields, such as feudal Japan, medieval Europe, and the Roman republic, Empire: Total War targets that period of revolution and rebellion, the 1700s. From the rumblings of the French Revolution to the American Revolutionary War, the wheels of modern history were set in motion thanks to a combination of hard-nosed diplomacy, yards of billowing sail cloth, and the flash of gunpowder. You get the impression the Total War team had been waiting for years to sink its creative teeth into that era.

Strategy on land and sea

“Empire: Total War is a revolutionary step for the series, both in terms of technology and gameplay. It’s our biggest and most ambitious title by some margin

Mike Simpson
Creative Director, SEGA

Such confidence is demonstrated by the headline feature: real-time 3D naval battles. In previous games, such conflicts were automatically worked out by the artificial intelligence (AI) as part of the game’s turn-based strategy gameplay, and hence didn’t provide players with the opportunity to bring their own tactics into play. The importance of naval power in terms of the wars in the Americas and Europe, climaxing with the Napoleonic Wars and the Battle of Trafalgar, meant it was necessary to include in Empire: Total War a real-time mechanic similar to the massive land battles that characterized the hands-on action element of the previous Total War games.

“After a number of years developing Total War on land, this has certainly been a breath of fresh air, but there’s been a lot of things to consider,” Simpson revealed. “At first, the sea seems a simpler environment, but as you dig down you notice complexities. The ships have a different movement and damage mechanic from what we’ve done before. Everything is continually in motion, which introduces a new set of challenges especially for the AI.”

One example is the importance of properly modeling the weather and sea conditions: high wind conditions create a choppy sea, which affects everything from how a ship can move to the accuracy of the gunfire.

“In the game, the sea is a complex surface, combining several components to generate the animated heights,” said Simpson. “This feeds into the motion of the ships, which use a flotation model, to move realistically up and down with the waves. In turn, this affects the damage results from cannon hits and so on. It’s an approach more weighted to simulation than crafted gameplay.”

A pirate ship is fired on from up close.

When it came to allocating system resources, graphical elements, such as shading techniques, reflections, refraction, and a pass to handle the particle effects, also had to be bundled up. “It’s a sizeable load for the CPU,” Simpson said. “It took some time to optimize, especially to get the sea surface right. However compared to the land battles, we’ve found that the less complex pathfinding and not having to render the vegetation frees up sufficient CPU budget for it not to be too much of a problem.”

Other new features that had to be handled included the use of buildings as cover for troops during land battles. Empire: Total War is the first game in the series to enable you to concentrate your men in and around buildings, such as farm houses, earthworks, and portable barriers. Adding in the knock-on effect for pathfinding results in deeper AI options that deal with counter-moves, such as how generals use their artillery. Other subtleties include the effects of bad weather on the performance of troops using gunpowder, while the game’s animation system has been completely overhauled to ensure that cavalrymen lower their lances in the charge and riflemen use their bayonets correctly. Such attention to detail is one of the reasons the Total War games have such a loyal fan base.

A well-balanced system

Such demands means the Total War’s engine undergoes continuous redesign as part of the game development process to make the most efficient use of new multi-threaded, multi-core CPUs, such as the Intel® Core™ i7 processor family.

An admiral watches as an enemy ship sinks.

“Our engine is architected in such a way that the bandwidth between the CPU and the GPU shouldn’t be a limiting factor because we only send data to the GPU through dynamic vertex and index buffers, perhaps a few megabytes a frame, which is quite reasonable for current architectures,” Simpson said. “In general, we have to worry more about pathfinding and the battle and campaign logic, which can be very CPU intensive. Thankfully though, there are powerful multi-core processors out there, and multi-threading will continue to help with this issue.”

As he also explained, getting the correct balance between a PC’s CPU and GPU is a tricky process, especially considering the range of systems from low-end laptops to monster, water-cooled gaming rigs that must be supported. “On its highest graphics setting, Empire: Total War can be made GPU-bound because of effects such as high dynamic range imaging, depth of field, and multi-sample anti-aliasing, but the load is varied by using level-of-detail settings which allow the game to scale,” said Simpson.

Using Intel’s development tools was a major part of ensuring would-be world conquerors will get the best experience their PCs can offer. The Creative Assembly used the Intel® VTune™ Performance Analyzer (Intel® VTune™) and Intel® Thread Profiler, as well as the Intel® Graphics Performance Analyzers (Intel® GPA).

“Intel VTune was very helpful on many levels, starting from providing a high-level overview, such as showing how much time is spent in the drivers, in the game, or in the D3D runtime, to finding and analyzing specific bottlenecks in the code,” Simpson said. “We used Intel VTune to speed up game loading process, pathfinding, the user interface, the graphics—almost every area of Empire: Total War benefited from using Intel VTune. The Thread Profiler meanwhile was utilized to verify the multi-threaded behavior in the game.”

Although Intel VTune is a well-known development tool, Empire: Total War was the first game from The Creative Assembly to gain advantage from time spent with the new Intel GPA.

“One of our key ongoing strategies is to design SEGA titles to play really well on a wide range of PCs, including laptops,” explained Simpson. “Our customers can expect to see a reversal in the normal trend where titles require ever more demanding hardware and start to see our games running better on lower-end machines.”

This is one area where use of the Intel GPA really helped, as the game’s engineers invested a lot of time in optimizations both for laptops and machines with integrated graphics. “The platform is definitely more limited—it’s very noticeable when you’re trying to squeeze the rendering engine into a graphics chip which does 2,100 MTexels as opposed to one which does 26,400 MTexels—but these are the challenges of PC game development. We feel the result has been a very playable and enjoyable game on those platforms,” Simpson said of the process, which involved close cooperation with Intel’s developer support team.

“We first investigated Empire: Total War using a pre-beta version of Intel GPA to look for GPU hotspots in the frame,” said Steve Hughes, Intel applications engineer. “The game uses some pretty special shader technology to render its realistic terrain, and Intel GPA showed that the simpler shader path that was supposed to be implemented for integrated graphics wasn’t being enabled at low-detail settings. Fixing this took us from 11 frames per second (fps) to about 15 fps.” Hughes continued, “Although the title is still in development, SEGA now has the frame rate well above 20 fps.”

During a naval battle, smoke billows after the cannons are fired, and the hull of the enemy ship shatters.

The result of all this hard labor is that the game’s minimum specifications are a reasonable 2.4 GHz single-core CPU with 1 GB RAM for Microsoft Windows* XP (Service Pack 2) or 2 GB RAM for Microsoft Vista* and a 256 MB DirectX* 9.0c-compatible video card that supports Shader Model 2.0. Indeed, the requirement for 15 GB of uncompressed hard drive space might be more of a burden for some people’s overstocked systems.

Of course, space aside, the other attributes a successful player of Empire: Total War needs are confidence and ambition, which will be particularly relevant for those who want to display their tactical nous to the world using the all-improved online multiplayer modes that use Valve Software’s Steam* technology. Wannabe Napoleons, the road to a new set of worlds to conquer starts right here.