Assassins Creed Evolution of an Engine

July 14th, 2009

Almost two years on I still have a special, warm place in my heart for Assassin's Creed. The open world it created may well be savagely short on gameplay variety, but the graphical realisation of the environments, and the interactive possibilities offered, proved to be absolutely irresistible. Going back to the game, its flaws become even more apparent: over and above the lack of mission content, the dialogue is over-long, poorly delivered and frankly boring, and the first 10 minutes are almost unimaginably, off-puttingly dull. But once you're wandering through the crowded streets of the Crusade-era Holy Land, the magic is back. Two years on and in many ways, there's still nothing to touch the world Ubisoft Montreal created.

It's fair to say that the sequel is one of my most eagerly awaited games of the year, and I was rapt by the presentation given at the Sony E3 conference, but also a touch concerned about actual engine performance. As regular readers of the Face-Offs will know, I was "gutted" by the performance of the PS3 version of the original game, lamenting the blurred visuals, the disappointing frame-rate and the corresponding lack of response from the controls. Based on what Ubisoft has revealed, is there a danger of history repeating itself?

In actual fact, there have been three major releases based on the Assassin's Creed engine, codenamed Scimitar. This codebase powered both the 2008 Prince of Persia game, along with Shaun White Snowboarding - very different games, suggesting a very adaptable engine. So I decided on a more expansive effort: performance analysis of all three games, in addition to a preview of Assassin's Creed 2, based on excerpts of the presentation given at the Sony conference. The aim: to measure progression of the Scimitar engine, with the hope being that we'd see corresponding increases in performance.

As it is, Assassin's Creed itself proved to be rather controversial back in the dark ages of Face-Off Round Six. I stand by my findings to this day, and was somewhat surprised by some of the reaction. Performance analysis using today's tools backs up what I wrote all those long months ago.

Getting for two years after the original Face-Off, finally we see Assassin's Creed performance metrics..

Performance is effectively locked on Xbox 360 at 30FPS, to the point where the game will desync from v-lock to maintain that all-important response from the controls. The cost of that decision? Torn frame measurement comes in at around five per cent of all the frames generated from the 60Hz output. The PS3 version, however, lacks any kind of v-sync at all (in excess of 40 per cent torn frames), and runs with a clear performance penalty... for the most part. What is intriguing are the blips where the game exceeds 30FPS. In none of my captures does it actually happen during gameplay, aside from within the interactive Animus loading screens, but nonetheless it suggests that Ubisoft turned off any kind of frame-rate cap, disabled v-sync and instead sought to pump out literally as many frames as possible. The result is a game that lacks consistency in both controls and visuals, making the Xbox 360 version a clear winner in just about every measurable form of criteria available. Any advantages to the PS3 code? The shadows have serrated edges in places on 360, but are smooth on PS3. That's essentially it.

Scimitar next emerged as the technology powering the visually impressive Shaun White Snowboarding. In fact, I was quite surprised to find that this was the Assassin's Creed engine at work at all. However, a quick look at the data on the release disc reveals the same .FORGE file system as used in the parent game, backing up Ubisoft's claims, and in a world where Skate can use the same level renderer as Burnout Paradise, anything is possible.

Shaun White shows a performance advantage to Xbox 360, but the inconsistent frame rate on both platforms makes it difficult to tell the difference cross-platform during gameplay.

Once again there is a disparity in performance - Xbox 360 seems to benefit from the addition of screen space ambient occlusion (SSAO), and there is a clear frame-rate advantage in the life-for-like scenes. Again, PS3 "has better shadows", which seems to be magnified somewhat due to the 360's extra post-processing. Curiously though, this time v-sync is engaged on both games, and there is no frame-rate cap. Both versions shoot beyond 30FPS, and while 360 has an advantage in the like-for-like scenes, often there is very little to choose between the two versions during actual gameplay. What is interesting is that there's nothing to suggest that the performance couldn't have been locked at 30FPS on both platforms, ensuring platform parity and a consistent response from the controls. As it is, the inconsistent refresh rate introduces a certain amount of judder on both platforms which isn't particularly appealing.

Where Scimitar reached its peak in terms of performance as a cross-platform engine was in the 2008 version of Prince of Persia. Developed by the same Ubisoft Montreal studio that brought us Assassin's Creed, it's one of the closest cross-platform releases I've played and suggests that the developers had overcome most of their issues with the PS3, with only the 1080p upscaling proving to be disappointing (thankfully disabled so long as 720p is active in your XMB).

Prince of Persia is probably one of the closest cross-platform projects released, with both platforms showing performance benefits in different areas, suggesting a high level of tuning for both consoles.

Performance profiling shows that the engine optimisations are widespread here. In exact, like-for-like situations we see both machines capable of out-performing the other at certain points while being essentially identical in all other areas. Even then, the only real difference comes down to a few torn frames. While Assassin's Creed remains arguably the more ambitious game visually, Prince of Persia is built on the concept of solid technology powering a beautiful artistic design, with wonderfully realised protagonists. And that's important. From a non-technical perspective, the script and interplay between the Prince and Elika is a particular highlight of the game - let's hope the writing in Assassin's Creed 2 is of a similar high quality.

So, with the past out of the way, what do we know of the future? Assassin's Creed 2 runs on an enhanced version of the Scimitar platform, complete with a new codename: Anvil. Its debut at E3 took the form of a five-minute PS3 play-through. We took a look at the entire presentation here, and in retrospect, while there's nothing in the analysis I'd change, one notable omission having replayed Assassin's Creed concerns the level of detail on faraway scenery: decent in the first game, but clearly improved for the sequel. The initial flybys and the Leonardo glider section showcase this effectively.

It's not just the LOD levels that that distinguish Anvil from Scimitar. It's just that the other improvements aren't quite so obvious in the presentation. Ubisoft, talking to German publication PC Games, revealed that the dynamically generated vegetation found in Far Cry 2 has been incorporated, as has the day/night cycle that worked so well in that game (the time of day also shifts in the E3 presentation). AI has also seen a significant increase - you saw the "seeker" intelligence in the E3 demo, but Ubisoft is also promising that some of your opponents possess enviable parkour skills themselves, which should make the rooftop chases from the first game that much more exciting.

Sections of the E3 Assassin's Creed 2 demo broken out for analysis. V-sync tearing cannot be accurately measured without the source video.

So, that's essentially the performance level of the PS3 game at E3. There's analysis of just under half of the original presentation (compressed video profiling requires a mixture of automated and manual checking and takes a long, long time). Torn frame measurement is effectively impossible on a 30FPS asset, but it's clearly an issue and one that I dearly hope is significantly lessened, even though this would entail a substantial level of optimisation in the short months until the game's release.

That said, this developer clearly has the proven ability to do so, and it will be interesting to see if the optimisation phase of the project sees performance that matches Ubisoft Montreal's impressive work in Prince of Persia, or whether the team is aiming for the same ballpark performance as the original game while incorporating new elements of technology. After all, all the complaining journalists in the world won't cut much mustard up against the stratospheric sales figures of the original game, currently standing at the eight million mark.

From a personal perspective, I'd hope for more, as Assassin's Creed 2 is up there with the new Modern Warfare as one of the most desirable new games of 2009. What gives me hope is that in terms of the quality of its cross-platform development, Ubi has barely put a foot wrong in the last year - Far Cry 2 is probably the only release that has seen a real tangible gameplay advantage on 360, but even that was limited compared to the perceptual gulf of performance evident in the original Assassin's Creed.

Next stop: gamescom. I'll be there, and I hope AC2 will join me...

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It became really rare for me to find good interesting game related articles lately, but after CGI-Quality posted the "Are you a graphical enthusiast? Come have a listen......

I began searching for good articles and this one was really a good and fun to read hope you enjoy it.

source:

http://www.eurogamer.net/articles/assassins-creed-evolution-of-an-engine-article

Edit: If you want to watch the videos go the source

seems i cant copy them

I love AC, ill get AC II and enjoy it.

^ yeah, but you should read this its a really good read

I want AC2 so much! I loved the first one although it had major flaws, but for this one they're are improving and removing the flaws

Wait was that comparison for the original or AC2?

If the latter, goodbye any chance of buying that game.

AC1 repetition held it back from being a masterpiece. I always knew all they had to do was add more mission variety and fix the combat which was mainly effective with counter attacks, while regular attacks were mostly blocked. Also if soldiers are a little less agile this time around when chasing you on the rooftops and not performing the same high flying moves as you (then all of my complaints would be fixed).

AC2 will be that masterpiece I believe. First day buy for me!

@Kantor

Why dont you read? He is talking about the engine and how its progressed and what will it show us in AC 2 and beyond XD

Too much for me to read.
Just want to say I'm still getting the game

Watching the first video I forgot how beautiful the world was and the shadows from the clouds above was outstanding.
I can't wait to see what updates will be in the second one.

Nice read sempai
As great as the first game was, you could tell the game was rushed and lacked in areas that could have made it a much much better game. I'm not worried about the engine or the graphics for that matter ( as they are already in the bag).What I really want to see is the potential of unlimitted action this game has and had in the first one. And seeing how Ubi has been really patient with this game for about two years, I'm really optimistic about AC II. People thought I was crazy when I put this game in my sig as "future GotY," but thats because I see it in a different light than everyone else.