Saturday 1 January 2011

Retro Tech Analysis: Virtua Racing (MD vs 32X)

Well, here’s the final part of our Christmas/New Year holiday coverage. Having mostly been put together after hours outside of a busy period at work this week, you’ll find a comprehensive and in-depth head-to-head analysis of Sega’s Virtua Racing.

I guess you could have see it coming from our earlier post. Regardless, it's certainly been fun putting it together. Anyway, we’ll be back after this sometime next week for the start of our regular 2011 updates, but for now, have a Happy New Year and enjoy!


Virtua Racing wasn’t the first 3D racing game to properly make use of polygons in the make up of both its cars and environments, although it did firmly set the president for all other arcade racers to follow. With a decidedly unique approach to realism – slidey handling mixed with spin-outs and flip-over crashes – it not only played differently to similar sprite-based games, but also delivered that 3D ‘wow’ factor by giving players four different viewpoints to choose from, and three highly detailed tracks to immerse you in its world.

It was also one of the first fully featured 3D titles to arrive on home consoles, battling against the likes of Starwing and Stunt Race FX on the Super NES for domination of the early 3D arms race before it really kicked off with the 32bit generation.

Sega first produced a version of the VR for the MegaDrive, using a similar method of in-cart enhancement as Nintendo, courtesy of the SVP (Sega Vitual Processor) chip - which handled all the geometry calculations and drew all the polygons for the game - but then transformed the idea into the fledgling 32X, a full blown add-on for the aging 16bit MD, along with a expanded release of the game, dubbed Virtua Racing Deluxe, in time for the machine’s launch in November 1994.

Today we shall be looking at both the MD and 32X ports of the game, comparing and contrasting the two for a special retro tech analysis of sorts. However, in order to capture screenshots for this feature, and to compare direct performance via (sadly unpublished) videos, we’ve had to use emulation for the basis of our analysis rather than actual hardware. Thankfully, in order to keep any rendering errors, and artificial performance anomalies to the bare minimum, we are running both games using Kega Fusion - the most accurate of all the MD emulators out there - with settings that closely represent the game running on original hardware.

So without further ado, let’s get on with it.


MD


32X

Like with the latest titles on both the Xbox 360 and the PS3, framebuffer resolution was as important back then when it came to image sharpness and clarity as it is now, with many games boasting a range of differing native resolutions. Virtua Racing is no exception. Rendering in 256x240 on the MD and 320x240 on the 32X, both versions feature the same overall 240p vertical resolution with the MD sacrificing some horizontal resolution for performance reasons.

However, both versions are also clipped to a 192 vertical resolution, with black boarders being used for the remainder of pixels rendered on screen. This means, that like in SF2:SCE, there are small boarders visible at the top and bottom of the screen that appear in PAL and NTSC versions of the game – the boarders are just larger in PAL 50hz mode owing to the extra unused screen resolution on display.

As expected there is also no anti-aliasing to be found - a visual effect which didn’t appear in home console graphics architectures until the debut of the N64 in late 1996. Instead polygons are presented in one of their rawest forms, flat shaded with pixel edges clearly being visible throughout.


MD


32X

In screenshots, the difference in native resolution comes across with one image looking smaller than the other. Although, on the TV this manifests itself with the MD version looking softer than the 32X game. As there is no scaling involved at any point, it’s instead up to the TV to manually stretch out the picture to the correct aspect ratio of the screen, which is done on a CRT by the electron bean scanning the lesser amount of pixels across a greater number of phosphors without any digital processing.

Softness is also increased by the MD version’s use of heavy dithering, used to simulate more colours on screen at once than what the system is capable of. Essentially, the MD game uses 15 colours for the polygon layer – 4bit pixels paired as single 8bit pixels, whilst the 32X version uses the system’s direct colour mode with 15-bit RGB and 16bpp in order to deliver 256 plus colours on screen at once. Using this mode, its actually possible for the machine to display up to 32,000 colours on-screen. Although, VRD doesn't do this.


MD


32X

As a result VR on the MD uses lots of selective dithering for representing many different shades of geometry for both the scenery and the actual cars, while on the 32X dithering is reserved purely for transparencies, with multiple shades and colours being used for polygon details.

In the screenshot above, you can see that on the 32X transparent objects such as shadows and selected smoke effects are dithered, whereas on the MD everything from the cars, the environment, and the effects use the technique. There are comparatively few areas of the stock VR game that don’t use dithering to balance out the lack of available colours for suitable 3D rendering. Unlike fully textured geometry, objects using flat shaded geometry require a greater number of colours to represent detailed imagery.

The downside to this, is that the heavily dithered image composition of the MD game leads to some noticeably fuzzy edges being present, along with making it more difficult to read the road up ahead – something which also isn’t helped by the game’s short draw distance.


RAW FB


Filtered FB

Dithering however, is largely only visible in unfiltered images. For example the above screenshots show, roughly, how the game would have looked via the MD’s – and indeed the 32X’s – video outputs using RGB SCART cables on a SD CRT. As you can see, dithering is greatly reduced due to the blending effect created by the filtered FB output, although some sharpness is lost as a result.


MD


32X

It’s fair to say then, that the Megadrive wasn’t set up with 3D rendering in mind. The system has no geometry processor, and features a CPU which is insufficient in rendering anything but the most primitive of polygonal shapes in small amounts. However, Virtua Racing manages to push around 6,500 polygons per-second via the use of Sega’s SVP chip – a DSP created by Samsung that handles all the geometry transform and rasterisation.

By contrast, the 32X has the benefit of featuring two Hitachi SH-2 CPU’s running at 23MHz in tandem, thus being able to churn out up to 50,000 polygons per-second in a best case scenario. How many PPS Virtua Racing Deluxe is pushing on screen we’re not exactly sure. However, it is definitely apparent that the number is significantly higher than what the MD using the SVP is doing.

On the other hand, the arcade version – powered by Sega’s Model 1 board – can deliver up to 180,000 flat-shaded PPS in-game, and does so with Virtua Racing at 30 frames per-second, so obviously it still has a sizable lead over both the MD and 32X games respectively.

In fact, the 32X game has much more in common overall with the MD version than with the coin-op. Although the cars themselves more accurately represent the arcade game in terms of raw detail, the trackside scenery, and the level of detail overall looks far more like an expansion of the modelling done on VR for the limited capabilities of the SVP chip powering the MD game. That said, the 32X version does a great job of representing the arcade on much weaker hardware.


MD


32X

The differences between each system’s hardware capabilities naturally have a great impact on just how well each version is replicated onscreen, with the added polygon pushing power of the 32X resulting in more detail cars and trackside scenery. Whereas the MD game just about resembles the coin-op, the 32X version on the other hand manages to replicate it a lot closer in certain areas.

The cars for example, are massively paired back on the MD. For comparison purposes we can only look at the stock formula 1 car, as the 32X game features the inclusion of two exclusive vehicles not in the arcade original or the MD game – the stock car, and prototype car. However, the formula 1 vehicle is bar far the most complex, featuring small interconnecting parts with more intricate geometric shapes making up its polygonal design.


MD


32X

Looking at the player’s car, we can see that its design on the MD is simply made up on more angular, square and rectangular-like shapes, with the wheels being directly attached to the side of the main body of the vehicle.

Around the front, and we can see examples of the curved design iconic to that of F1 and IndyCar vehicles, although decidedly blocky and very low poly. It can be quite hard to recognise the individual details which make up the various parts of the car in the rear, chase-cam view in comparison to both the 32X game and the coin-op.

The 32X version on the other hand, has a main vehicle that is not only more intricately detailed but also one that better represents the ones found in the arcade original as a whole. As you can see above, the wheels are now connected to the main body via individual rods, just like they would be on a real F1 car.

In addition, the front structure is more curved, and features an increased cone-like design, which better replicates the aerodynamic chassis required for high-speed racing. There is also better separation of the front, cockpit, and rear of the car, with the individual elements being more identifiable than on the MD version.

Despite the more detailed nature of the cars in general in the 32X game, there are some elements of the blocky MD vehicles that more closely represent the arcade version in some scenes.


MD


32X

In terms of the environment, both versions are at times reasonably close to each other, with the overall landscape holding similar shape and geometric composition despite the differences in polygons used throughout. The 32X version however, features bulked up parts of the environment using more geometry and a greater number of on-screen colours to smoothen off the rougher edges. Mountains in particular not only look larger on the 32X, but also feature much smoother transitions between gradients.

In other areas we can see more in the way of smaller environment details. In particular, the ferris wheel on the fairground is noticeably more complex in VRD compared to the MD game. While similar things can also be seen with the stands throughout the opening section of the Expert course, along with additional extras such as more in the way of metal railings and other trackside structures.


MD


32X

The pit crew look largerly identical, with only minor tweaks and featuring a different colour scheme. They appear to be constructed from various rectangular and square shaped boxes in combination with strips. Obviously, due to the poly starved nature of both the MD and the 32X, neither version showcases anything near approaching a human-like representation of people.


MD


32X

Strangely, there are areas in which the 32X game seems to feature less in the way of trackside detail than the MD one. In the above screenshots we can see what looks like a group of small white buildings upon the mountains in the MD version, while in the 32X version, although the mountains themselves appear fuller in terms of size and complexity, the buildings have been removed.

Across the whole game there are other such discrepancies between the two versions, in which some subtle details have been removed in the 32X version in order to accommodate the higher poly - and in itself more detailed - baseline scenery instead. On the plus size, the courses themselves are made up of larger objects which bring a far greater sense of scale to the proceedings compared to the standard VR on the MD.


MD


32X

Of course not all of the changes between VR and VR Deluxe are technical enhancements and compromises. A few differences appear to be purely cosmetic. Take for example, the sign pictured above from the Expert Course: on the MD it says “Sonic”, whereas the same one is displaying “32X” for Sega's upgraded Deluxe version.


MD


32X

The Course Select screen has also been updated in the 32X version from both the MD and the arcade. Each course has been given a rotating 3D model on the selection screen, along with the cars being given the same treatment on another menu. However, in the original arcade and MD games, the course select screen simply features a still 2D bitmap image instead.

The improvements don’t have a baring on the overall conversion quality of the two console conversions, although the spruced up presentation elements of the 32X game makes initial experience feel a little fresher and more in-keeping with the early 3D revolution that was taking place at the time.


MD


32X

Draw distance however, does greatly impact on the level of enjoyment you’re likely to get from each game, not least of all because the dithered nature of the MD version also further affects this, sometimes adversely – the fuzzier overall look makes seeing distance objects somewhat more difficult.

While both versions initially appear to have similar levels of polygon pop-up, there are instances where the 32X game suffers from closer on screen draw-in of certain objects, whilst the MD version features a more consistent level of draw-in on the whole. Smaller environmental details tend to pop-up later on the 32X, while the larger chunks of scenery usually appear at the same time, or slightly earlier than on the MD.

However, this peculiar observation seems to be track specific, with most of the offending examples happening on the beginner course. On most of the other tracks, pop-up seems to be near identical for both games; that is to say, while it can be rather intrusive at times, it is for the most part tolerable once you get used to it. Although, using the in-car view is pretty much useless, with the default, and higher viewpoints providing by far the best gameplay experience due to the closeness of the draw distance and overall image quality as a whole.


MD


32X

Moving on, and performance is rather interesting in Virtua Racing, not least of all because the game runs at such low framerates by modern standards, but because it still feels rather smooth on both formats despite this. Obviously, as already mentioned, the arcade game runs at a solid 30fps with full v-sync enabled - something that neither of the two home console conversions could manage without further heavy cuts in detail, and even then it would be virtually impossible on the MD using the current SVP chip implementation.

Instead, we see the framerate on the MD version halved in comparison to the coin-op. Virtua Racing runs at a solid 15fps on Sega’s 16bit platform, right in accordance with the SVP chip’s 6,500 polygons per-second at 15 frames per-second in-game limit. Even when spinning out of control, or crashing with other vehicles before flipping your car over in a similarly ridged fashion to that of the arcade game, VR never slows down.

By contrast, similar games from the time – like the Super NES’ Super FX powered Stunt Race FX – run at anything between 12-15fps depending on engine load and scene complexity, making Sega’s conversion to the MD all the more impressive. This feat is further enhanced when you consider that the game allows you to select all four views from the original arcade game – one of which sees you looking down on the race via an ‘eye in the sky’ type position, pushing engine load without faltering.

Interestingly, when playing this version of the game first, self-contained and away from other versions, the framerate feels pretty smooth despite being so low. It’s only when put up against Virtua Racing Deluxe does the lack of fluidity strongly manifest itself.

Jumping to VRD on the 32X, and the difference in smoothness is instantly noticeable. Like with VR on the MD, Deluxe is fully v-synced with no visible screen tearing occurring at any point. However, unlike the MD game, it comes even closer to matching the arcade game’s 30fps benchmark. Here, we see a solid 20fps update providing a clear extra level of fluidity above that of the MD version. Control not only feels smoother but also more responsive.

In any case, both home versions of the game pale in comparison to the coin-op, which not only boasts a much smoother framerate, but also vastly superior levels of detail. However, both the MD and 32X ports are incredibly accomplished, and for their time represent some of the very best in arcade to home experiences any console could offer.

Overall performance across both home versions is solid, free of any screen tearing, but most of all, smooth enough to allow for a fully playable experience, even if the MD game feels more than a little rough around the edges after sampling the 32X version.


MD


32X

What is surprising, is that Virtua Racing still holds up relatively well after all these years... on the 32X at least. Sure, the draw distance is a bitter reminder of the mixed travesty that was in some areas the Saturn conversion of Daytona USA - often impeding your ability in reading the road using the cockpit view - but the overall modelling of the environments, the look of the cars, and the crisp, responsive control, means that the game, to this day, is still very playable.

On the other hand, the MD version isn’t quite so lucky. The heavily dithered nature of the scenery, and the blocky, low poly enemy cars means that both sharp turns and other vehicles are sometimes very hard to spot before colliding straight into them. However, the game’s 15fps update still feels surprisingly smooth considering just how low it really is. Most of the problems don’t stem from the lack of overall fluidity, but from poor image quality and a large amount of polygon pop-up. Both of which do far more harm than good.

That said, getting Virtua Racing running on both of these consoles to a playable, even enjoyable, standard is somewhat remarkable. But whether this was the right thing to do, instead of focusing on the Saturn in the first place, is anyone’s guess. Either way, for most people Sega’s 16bit console and 32bit mushroom add-on was the only way to play Virtua Racing at home.

Of course, today that’s a moot point. Seeing as a definitive version of the game has been available for the last few years on the PS2 - its 60fps, and with the arcade game being near perfectly emulated in MAME, you could argue, is there really any reason to pick up such archaic conversions?

For anyone who likes to play games on proper hardware, free from the glitches and disconnecting feel sometimes offered up by emulation, then yes, I would certainly say so. In which case the 32X game is clearly the one to go for. Representing a fine balance between heavily cut down home console port and excellent arcade conversion, it manages to out perform the botched Saturn version in both graphics and gameplay overall, whilst still being a thoroughly faithful adaptation of Sega’s first 3D gaming sensation.

1 comment:

  1. Interesting article, thanks. I will have to go look at some YouTube videos of both versions now, Although the frame rates don't come out quite so well in YouTube. I didn't realize the Saturn version was worse than the 32x, very disappointing... The only version I ever played was the 32x, my neighbour had one

    ReplyDelete