Relic Entertainment came onto the PC gaming scene with the very strong debut of their three-dimensional RTS, Homeworld. Critically revered and also an excellent seller Relic has since gone on to make numerous real-time strategies, including Warhammer 40,000 and Impossible Creatures for Microsoft, before being acquired by THQ. Last year Company of Heroes was deservedly acclaimed and winner of many "Game of the Year" awards as Relic brought the strategy back to real-time strategy games, doing away with most of the repetitive resource collecting and putting it back on tactics, what units to use when and where and how to corner and annihilate a competitor. An excellent blend of tacts with an amazing looking engine which brought new life to the WWII genre. The game was also built from the beginning to eventually make use of DirectX10 when it was to be released with Windows Vista and not long ago that promise was finally fulfilled and Company of Heroes became the first commerical DirectX10 game on the market (Capcom released a DX10 demo earlier of Lost Planet).

We looked at DirectX10 performance of Company of Heroes earlier in the month when the 1.7 patch was released but today we're taking a closer look at the visuals and the impact of DircectX10. As we're no programmers, we'll let Relic say it themselves in this post from their forum documenting the graphical improvements in DX10 version:

Soft FX Blending

In previous generation games, 2D sprites are often used for explosions. Where these intersect the ground or other objects it becomes apparent these are simple 2D cards, not real 3d objects. CoH uses multiple render targets to store the depth information to a 2nd texture before rendering our FX. Using this depth information we can properly blend as the intersection approaches to maintain the 3D illusion.

These are always enabled, unless the video card runs out of memory. When doing comparison benchmarking at high resolutions and anti-aliasing settings it is important to check the warnings.log for texture creation failures due to running out of memory to see if this feature was silently disabled which will result in a small performance gain for cards that run out of memory.

Litter Objects

Previous generation games generally have flat terrain with a few objects such as trees or barrels placed on them for variety. CoH advances this by adding small procedurally generated 'litter' objects. These are added to all existing levels without requiring any work from map artists by adding objects based on the material type of the terrain. With the Direct3D 10 renderer users get to have real 3d models of small plants growing in the fields or real 3d models of rocks on the roads instead of just paintings of rocks on flat terrain.

The number of objects is tied to the model quality slider in the graphics options menu and uses the Draw Instanced API.

Short Grass In addition to having litter objects areas of the maps where grass is growing will have 3D grass in Direct3D 10. Grass 'shells' are drawn over the terrain using the Draw Instanced API so that soldiers will be able to walk on real grass instead of a flat painting of grass.

This is enabled in the options menu by selecting the Ultra detail terrain setting.

Point light shadows In Direct3D 10 mode all lights can be shadowed. Whether it is a huge explosion, a street light, or even a match lighting a cigarette, the light has the potential to be shadowed.

This is implemented by rendering the entire scene is to all six faces of a cube map for each shadowing light using a combination of the Draw Instanced API and the Geometry shader. As long as shadows are enabled this feature is enabled.

General Improvements

As all the lighting in Direct3D 10 is 100% per pixel, the shadows are more softened, the lighting is more detailed, and there are more shadows the pixel shaders are up to five times longer than they were in Direct3D 9 mode. Many of these instructions can be skipped in typical day missions with only a few point lights, but night missions will tend to have more point lights which will require more work to draw the shadow maps and then more work to render the world scene with more active shadow maps.

In Direct3D 9 only the main sun/moon light was normal mapped; the ambient light and other lights were calculated per vertex. This is most noticeable when the object you're looking at is in a shadow and only ambient light is on it.

On a first-hand basis we also immediately noticed a difference in graphics quality with a much sharper, cleaner, and dynamic graphics. Sometimes it is definitely hard to tell if you play Company of Heroes zoomed out most of the time as we do but when you zoom in the difference in quality is dramatic. Rocks and other litter cover the landscape, the textures from the ground to the player's faces seems dramatically improved and lighting starts to shine with DX10. It's not night and day all the time but if you've got a high-end system and have been looking for something to show off DirectX10 on then this is the game to do it on. Here are a number of DirectX10 vs DirectX9 screenshots with DX10 on top. Click for a HD, 1920x1080 resolution.

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