Tech Analysis: Forza 3 Demo
Digital Foundry takes a closer look.
Forza Motorsport 3 is due for release at the end of this month, and while we're reserving some time for a tech analysis on the full game, the recently released playable demo also offers up a number of decent performance metrics, some neat tech stuff, and a number of interesting decisions by the developers at Turn Ten.
A quick analysis of the in-game 60FPS mode throws up a couple of interesting graphical quirks. First up, you might notice a stippled "screen door" effect on all the surrounding vegetation: a similar effect is in play on SEGA Rally. This is known as "alpha to coverage" and it's a low bandwidth method of giving some kind of transparency. You can also see it in effect at the overpass near the end of the circuit.
The effect has almost certainly been included to help sustain 60FPS. Literally rendering fewer pixels helps contain overdraw, while the framebuffer format might also be important. On some of the formats supported by Xbox 360, transparent so-called alpha pixels take twice as long to render - not good when you're looking to maintain a smooth 60FPS.
Forza's reputation for 60FPS gameplay remains virtually unblemished in this analysis, with just one minor slip during the action. The other blips are reserved for switches between the game cameras; basically unnoticeable during gameplay.
Also interesting is the inclusion of what's known as a negative LOD (level of detail) bias. In the normal scheme of things, high resolution textures are reserved for areas of the game world close to the player, with lower resolution assets deployed further away. In the case of Forza 3, the road textures detail levels are much higher than they need to be for the available resolution, and this results in some superb definition at the expense of some shimmering as the detail is downscaled. Quite why Turn Ten has opted for this method over some kind of adaptive anisotropic filtering is a bit of a puzzle bearing in mind the relative paucity of the 360's texture cache – it may well simply be the case that the developer had the GPU time to spare.
HDR tone-mapping has also been included, although its usage is somewhat muted, presumably to stop over-the-top lighting effects affecting the gameplay.
Analysis of the game's replay mode suggests that Turn Ten has taken a leaf out of Polyphony Digital's book and has opted for increased detail and effects, sacrificing the 60FPS refresh rate in the process, on the track-side cameras at least.
A rock solid 30 frames in the replay sections, though a soft v-lock appears to be in play. On scene changes in particular you get the odd torn frame.
At this stage of the game, superior motion blur effects are added, anti-aliasing is upped to a smoother 4x MSAA and interestingly the game runs with a soft v-lock at 30FPS. In this particular replay you don't see the effect much at all, but torn frames can crop in here, particularly on scene-changing moments. On the final game it'll be interesting to see how the engine copes on really challenging scenes. Also intriguing is that the alpha to coverage effect looks different in the replays. Combined with the mask generated by the 4x MSAA, it has the bonus of adding additional colour shades.
However, as some have pointed out, it is very curious to note that the car models employed in the replay mode are not of the highest quality (judged by the standards of the models elsewhere in the demo). The angles shown of the cars at the beginning of the actual race employ the highest LOD (level of detail) models, whereas the replay shows significantly less detailed meshes for the vehicles. In all honesty, this is a bit of a mystery, maybe even a bug that will be corrected in the final build.
Check out the detailing around the headlight. The replay model (right) appears to be using lower detail 3D models when compared against the intro cameras on the actual gameplay (left). Very curious and it could be a bug in the demo code.
Onto the issue of crash damage then, and it's interesting to see how Turn Ten has implemented its model. The car has been divided up into different sections, and each has a pre-determined, incremental level of damage, with a number of removable parts. In the course of general racing, the effect is fairly realistic, but it's still somewhat removed from the reality of a high-speed crash during a real race. There's no deformation along the lines of Burnout Paradise, for example, and even the dynamically generated "battle damage" in the Xbox 360 version of Burnout Revenge hasn't been replicated.
Attempts to play Forza 3 as though it's Burnout show both the strengths and weaknesses of the damage model.
So, what's the big deal with crash damage any way? The bottom line is that it's a hugely important part of games that purport to be racing simulators. High speed racing is synonymous with danger, and risk must carry the threat of dire consequences... the days of ramming opponents with impunity and bouncing harmlessly off solid walls should be well behind us. The danger principle is one of the core philosophies behind Burnout, and it is interesting to note that the Criterion game's over-the-top, enhanced crashes are still vastly more realistic graphically than anything seen in Forza 3.
Interestingly though, Forza 3's model appears to have much in common with the latest work by Polyphony Digital on Gran Turismo 5. While our first impressions of the crash damage in GT5 at gamescom were not so positive, recent footage from the Tokyo Game Show suggests that Polyphony has made big, big improvements over the GC code. Removable body parts have been joined by localised damage. Whether it is dynamically generated, or pre-determined like Forza 3 is something we won't be able to confirm until there's better video or preferably some hands-on code to analyse.
It wouldn't surprise us at all if the damage is indeed pre-determined on both games. The Burnout titles have the luxury of using non-licensed cars; Criterion are the lords and masters of their creations and can do with them whatever they see fit. Both Forza and GT5 don't have that luxury, and it may well be the case that the developers need to get manufacturer sign-off on all the in-game representations of their vehicles. Detachable parts and pre-determined damage would be a convenient solution.
Forza Motorsport 3 is an impressive-looking game. Chances are that you've played the demo and you're as impressed with it as we are. Fingers crossed we can get a closer look at the final game pre-release...
Many thanks to Alex Goh for his input into this feature.
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Comments (67) Latest comment 2 years ago
Comments threads automatically close after 30 days, but please feel free to continue chatting on the forum!
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/Loves these articles. Let the haters hate.
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Odd article...
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...Try telling that to 99% of online Forza 2 gamers! If only it were true, but sadly this feature is pretty much a waste of time. People bad enough to see the damage model in action get bored of it and turn it off, and those good enough to race with it, probably barely get a chance to see it in action by racing properly. Maybe I'm strange, but I'm only interested in watching races to perfect tune-up or watch a race I feel I did well. Watching a crash... as the article mentions, there are better games, specifically set up for crashing if that's what turns you on about racing.
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That's pretty good, among the best of this generation (only Fight Night 4, Burnout Paradise, GT5
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See GRID.
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I'm pretty sure its not a bug. The car shown at the start of the race uses the same high level model used in the car select menus. It is not used during the race or the replays though. The cars still look good to me though.
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Or perhaps it's just not particularly interesting from a technical standpoint, even though a lot of people are talking about it. Personally I noticed it (and the rather flat appearance of the cockpits) for about the first 15 seconds of playing the game but didn't give a hoot thereafter. It seems to be a game which looks better the more time you spend with it.
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However when the game the game is in motion, as DF says its looks good. I doubt anyone will be shouting: "Stupid alpha to coverage!" or "Goddam freekin' muted HDR Tone-mapping!" while they play.
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Please, T10 & PD, concentrate on the racing. Leave crashing to Burnout (and GRID, apparently).
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/end troll..lol!!
As long as there is internal damage, then thats fine by me. At least there is a performance (or DNF) penalty for driving like a Hammond.
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I really couldn't disagree with this more. You only see it when you screw up and it's not remotely realistic anyway. It's a fun addition but that's about all.
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Turn 10 have obviously compromised in order to achieve a tear-free 60 fps - as they should have - so I couldn't describe it as near photo-realistic looking like Gran Turismo 5/Prologue. Lighting isn't especially convincing to me and there's lots of noticeable aliasing on the barriers and cars. It looks good enough in-game and looks better than Forza 2, thank goodness, but I doubt it'll be praised for its visuals. Still, the graphics are not the reason I'm buying the game anyway and I'm sure it'll excel in every other department.
/Is looking foward to playing it.
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F3 and GT5 seem to use basic rigid-body physics to make the cars ("adamantium chassis syndrome"
Maybe next generation will be able to do a full physics simulation, chassis stiffness included, and we can break cars in two, make them cabrio by crashing them sideways into a tree...
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Now, I can't comment on GT5 as I haven't played it (due to it not being released yet
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What a lot of people fail to mention for some reason, is that GT5P has some issues of its own - tearing, lack of AA, etc. I don't know why these things are only mentioned in regards to Forza.
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I don't even have a fucking 360 though >
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'Dirt2 is a good example of calculated damage deformation that's not predetermined - and that's on real cars, not made up models like burnout. This makes me think the damage limitations in Forza/GT5 are probably more down to performance problems and the technical difficulty of making the damage look good. After all the Colin McRae / DiRT games have been doing damage for a long time and must have lots of experience at it. '
Get a life
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Sorry, it's the usual yawn. What a jerk
I've just read the second half of your post. You really are a 'C'
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Also ,DF bias shines through again imo. Such a let down from a hyped game as this would be like a 3 page story for PS3 saying the tiniest stupid details.
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Also ,DF bias shines through again imo. Such a let down from a hyped game as this would be like a 3 page story for PS3 saying the tiniest stupid details.''
LOL LMAO,i have GT5p and looks like crap next to Forza 3 who are you trying to kid? i bet you haven't even play the demo,let alone owning a xbox 360.
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Another shitty pointless, clueless Digitial Foundry Article!
More of these please!
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How old is the GT5
Yeah, comparing an old work in progress to a demo of a finished game. *slow claps*
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DF's bias also explains how they loved Uncharted 2's tech so much, doesn't it? Oh, wait; it's almost as if they're not biased at all, it's just fanboys getting annoyed when their chosen favourites aren't unreservedly praised and their competitors aren't roundly trounced, regardless of worth.
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edit:google gives me nothing, it must be DF making stuff up to sound clever
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neat!
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Plan of action:
Sell Dirt 2 (it was good knock-about fun for a few days but the Forza 3 demo has blown it out of the water).
Buy Forza 3
wait ages...
Buy GT5
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Read ALL the comments. I wasn't the first to mention GT5, or compare its graphics to Forza.
Suck on that egg!
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And one that I want to be part of.
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What a remarkable turn of events.
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but the ai, textures and scenery are really good. much better than gt5p, which when talking about the ai, isnt hard. the mountains on the demo circuit look stunning and full of detail. i will buy f3 coz i need a racer but i dont want it to be dull and lacking variety like gt5p and f2 did
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Of course they are. But at the end of the day they are both GAMES so importantly the gameplay must be the priority
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But in all seriousness, what are you even in this comments section for - other than troll? Go back to the GT5 forums and enjoy yourself, and let us who are looking for Forza do the same.
You're never going to convince anyone that anything is better or worse, so just quit trying. And whether one is truly better looking than the other is really inconsequential to which game is actually better. And I'd put my money on Forza begin the better all around game.
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I'll give you a +1 because you either have some issues or are taking the piss. Either way, +1 for making me chuckle.
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The lighting model used by PD is stunning. However, it's a long way from photorealistic. Real life isn't that oversaturated and over shiny. GT5 seems more "filmic" than "realistic", more Michael Bay/Tony Scott than anything approaching reality.
Don't get me wrong, it looks fantastic. Well, fantastic in replay mode, and pretty damn good in-game. But it's just too over the top to be photorealistic.
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Darren
07/10/09 @ 08:17
ignore poster | #43
@rotmm - I've played GT5 Prologue and seen enough of GT5 in-game footage to see for myself that it looks more photo-realistic that Forza 3.
But..if the car physics are floatier..maybe that's a 1up in Forzas direction eh?
I think there's little point in comparing them...Forza 2 was a great racing sim in it's own right, and it looks like F3 will be as well. Sim wise turn 10 are doing a good job
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]http://ww w.metacritic.com/games/platform...[/link]
Reviews are coming in..
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]http://ga mersyde.com/stream_forza_motors...[/link]
Poor textures, 2d bush, bitmap background. So it's confirmed, demo track is the best looking one.
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Which one looks better I think is more a matter of taste. I prefer the overall look of GT5P, but there's certainly something to be said for F3's rock solid framerate.
However I'm not too convinced about the handling in F3. It's certainly not bad, but it somehow didn't all feel very natural to me. Like it primarily aims to be a driving sim, but at the same time wants to attract some arcade fans on the side too.
Turn 10 can say what they want, but I found GT5P's handling still feel more realistic and satisfying, provided you turn off all driving aides (otherwise it's quite horrible, to be frank).
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You do realise Forza 3 handling can be tweaked from full on sim to downright casual arcadey? What setting did you play it on?
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You want the very best? Well you better be prepared for the wait while everyone else is having fun now. The choice is yours.
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Btw pacthes and updates are and will always remain free. And I bet PD release DLC for GT5.
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well they had no prob making people pay for a demo so don't hold your breath!