On the Right Track: Deciphering the Cart Tunnel

Happy September everyone! Stuart Attenborrow here, a 3D Artist and one of the team’s camera matching specialists.

As you know we’ve been focusing on Boiler Island for most of this year. That trend has continued post-Mysterium and we’ll share our overall progress with you soon, but I’d like to take a moment to take you behind the curtain on a specific area I’ve been working on recently. If you’ve been in our official Discord server you may have seen my rant about the cart tunnel on Boiler Island. Today’s update is a bit of a director’s cut of that rant, complete with example pictures. Enjoy!

The cart tunnel is one of those areas you breeze through without much thought. It’s dark, and you only see it for a brief time before being dumped unceremoniously down the chute and into Boiler Island proper. It’s possibly for these reasons that there are a few rough edges in the tunnel that nobody really notices (myself included). Until you try to rebuild it, that is.

Here are my top five quirks that the team identified as we brought this area into real-time 3D.

Number One: Brace Yourself
For starters, here is one that’s easy to spot. As your cart rolls into the tunnel you can see that the track bracing runs all the way to the end of the line. If this is the case, how exactly do you fall down the chute? Let’s check that out.

As the bottom of the cart opens and you fall through, not only does the bracing mysteriously disappear, but if you take a look at the Boiler Island arrival animation frame-by-frame you’ll notice that the bottom of the cart has gone missing entirely! Magic!

Number Two: Shifting Objects
Another significant change between shots. Depending on your position in-game, a small rock and a support pillar for the cart track will come and go. We can only assume changes were made right up to the last minute, and some stills were not re-rendered. That’s game development for you!

Number Three: An Impossible Turn
At the very end of the famous cart ride from Jungle Island, there is a period of complete blackness before the player sees the light at the end of the tunnel (literally!). The cart then turns on a dime around the corner to hit the buffer stop and end the ride. Unfortunately for us, it turns out that corner is actually way too sharp for the cart to actually make!

Number Four: Spot the Difference
As you might expect, we are experts at playing Rivenese spot the difference. Have a look at the above image, and you might spot it too!
The lever next to the cart is missing in the arrival animation, but reappears when you’re standing next to the cart. It also moves between the few images within the tunnel. We assume returning via the cart was a later addition.

Number Five: Mechanical Faults
Our final nitpick is a little more technical. On the other side of the water when travelling to Jungle Island the cart runs out of oomph. It slips back slightly, but then something interesting happens. You can hear the sound of ratcheting as it continues it’s ascent. It only makes sense that this should be a chain hill and rack mechanism like those you’d see on a roller coaster. There’s only one problem though – there’s nothing visually in the game suggesting how it’s achieving this. The track is the same as it’s always been. Perhaps the cart is far more advanced than it looks…

We hope you’ve enjoyed this little tour through our daily work to parse the world of Riven into real-time 3D for you all to explore. It’s one hell of a ride!

We apologise to those still waiting on the recordings of our Mysterium presentation. The folks at the Mysterium Committee are still working on editing down the whole convention’s worth of footage, and these things take time! We’ll be sharing the videos as soon as we receive them.

Edit: It looks like our Mysterium presentation has been up on the MysteriumCon channel for over a week! You can see it here. Thanks to user commenter P-K-V for letting us know!

Please welcome our newest team member, Alexander Diener – a multi-talented programmer!

15 Responses to “On the Right Track: Deciphering the Cart Tunnel”.

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  • Andreas Says:

    That is interesting. Is it ever possible to see the wheels on the cart? I suggest the only way it can make that turn is if the wheels are mounted on a moveable joint on the axle. Maybe the reason why the chain is not visible is because the cyan team wanted to save some time? I also wonder why the cart only runs out of speed in one direction. It seems impossible that it have enough speed to get up that steep track towards boiler island without being pulled by a chain, especially as it is constructed for carrying a heavy load of logs in that direction.

    • Stuart Says:

      In the original it’s hard to get a good look at the wheels on the cart which is why it didn’t matter. But in real time you only have to look down and you’ll see them. Not sure what we’ll do on the turn yet.

      For the chain hill they either ran out of time or left it out for other reasons. Given that the rings have rendering errors from boiler to jungle but none in the other direction, I’d say they didn’t want to rerender the animation— even for something that prominent.

      The apparent speed was another item on my longer list. Jungle is higher and therefore the overall idea of there being the need for a chain hill on jungle is sound. The issue is on boiler. When you come out of the water you travel at a linear speed until the dock, implying a slightly declining track. But returning to jungle shows that you build up a huge amount of speed on the same section of track. Only one of these can be true.

  • Joe Douglas Says:

    For the sharp turn,could the cartnotjist tilt up on to two wheels?

  • P-K-V Says:

    Great post! always cool to see things that we missed playing the game. Side note, it looks like they’ve had the Starry Expanse presentation up for over a week now: https://www.youtube.com/watch?v=796NtktmhwM

  • jd36 Says:

    As to #5, the track seems to have a central rail that vanishes around frame 72 of this gif. Perhaps that has something to do with the mechanism?

    • Jeff Says:

      That central rail is actually below the track and most likely meant to support and provide power for the rings.

    • Stuart Says:

      The central rail is used during the ring section presumably to hold and/or power them. This element ends just after the last ring in each direction and sits well below the track. For a chain hill to work it needs to sit above the track bracing so we’d need to add it on top. It’s still undecided whether we’d add it though.

  • Jonathon Wisnoski Says:

    Very Interesting. Could you perhaps enlighten us how you have solved, and plan to solve these issues and their like? Do you look for clues as to which screen portrays the “correct” world? Do you just pick the one that looks best? Do you fix missing objects always instead of removing extra ones?

    And even more basic, are all these problems to be fixed, or might some mistakes be left as they were originally?

    One example, specifically, do you plan on adding a cart hill ratcheting system, or will you just leave that as “magic”.

    • Stuart Says:

      Most problems like this have enough images that corroborate the intention so we go with that. This usually means adding objects back in. From my experience it’s either a difference between an earlier vs later render in the development lifecycle where minor changes occurred. Or it’s one of the cases where they fiddled with a render to get the best composition and intentionally hid objects to suit.

      Fixes happen on a case by case basis. The chain hill is not a big deal and I’d be happy to leave it out if everyone else feels the same way. A trapdoor in the cart and gap in the bracing to fall through will have to happen as it’ll be plainly obvious in realtime if you look down and see the floor disappear or clip through the track.

  • Averagemoe Says:

    Maybe the bottom of the cart flips open so that the floor is behind you.

  • Sehrvis Says:

    I hope for consistency that you make that rock disappear and reappear depending on where you’re standing.

  • Doofus Says:

    oh my god that’s amazing, looking forward to it as i just finished the realMYST masterpiece edition xS struggling to be patient!

  • Andrew Says:

    Regarding point #2, it might be funny if those objects just appeared and disappeared depending on where you’re standing. I assume that wouldn’t be practical though 🙂

  • Robert Says:

    I’d always assumed that the bar running in the center of the track was meant to imply a chain lift. As you are approaching boiler island, it ends just after you get to the top of the ascent.

  • TheGalantMAN Says:

    Here’s my nitpick: “as it continues its ascent”, without the apostrophe*

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