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Author Topic: vertical junctions  (Read 1427 times)

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Offline Freahk

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vertical junctions
« on: February 08, 2020, 12:19:04 AM »
It seems vertical junctions have a bug and don't work when diverging to the upper level.

See the attached savegame for a reproduction case. The bus in the "working" line will work properly but the bus in the "partly working" line will turn around because it can't find the short way through the junction.

obviously it should not be possible to buid that "vertical junction" construct at all.

Offline prissi

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Re: vertical junctions
« Reply #1 on: February 08, 2020, 12:10:04 PM »
Would be nice, if you indicate a pak set for such report.

But you are right, in principle the construction of those is forbidden. So the error is that Simutrans allow the construction. So how did you make one?

Offline Freahk

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Re: vertical junctions
« Reply #2 on: February 08, 2020, 12:53:44 PM »
Sorry, I'm used to extended bugreports, where the pak128.britain pakset is implyed if not explicitly mentioned.
I see there is no such "default" for standard. It was created in pak128 but will also work with any other pakset, originally encountered in pak128.britain-ex.

It's all about abusing the nature of bridges starting at a slope considering the base height of the slope rather than the actual track height. Lowering an elevated section above will thus be allowed.

Steps to reproduce:
1. Build an elevated way above a full height slope.
2. raise the sloped end of the elevated way to become flat using the "build artificial slopes" tool.
3. build a bridge at that slope
4. lower the elevated way again
5. connect the bridge to the slope using any ordinary way of the same waytype
6. Enjoy your partly working vertical junction

Offline prissi

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Re: vertical junctions
« Reply #3 on: February 09, 2020, 12:13:37 PM »
Sorry, I could not produce this at all. I also do not understand the need for the bridge, since the bridge is no at the junction. I am also not allowed to lower the slope. Some more information, please.

Offline Freahk

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Re: vertical junctions
« Reply #4 on: February 09, 2020, 12:39:40 PM »
Can anyone else reproduce this or give any hints on this? Maybe Vladki, as I showed him the procedure ingame?
When strictly following these 5 steps, I can reproduce it, so further details is a little bit difficult, I guess I have covered each single required step in detail.

Edit: A step-by-step imaged construction instruction of these steps will follow. I really don't know what else I can do here...

Offline jamespetts

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Re: vertical junctions
« Reply #5 on: February 09, 2020, 12:41:23 PM »
Perhaps a short video to demonstrate the steps to reproduce might help?

Offline Freahk

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Re: vertical junctions
« Reply #6 on: February 09, 2020, 01:49:29 PM »
See the attachments

Offline Vladki

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Re: vertical junctions
« Reply #7 on: February 09, 2020, 07:47:53 PM »
Imho the bug is not that this arrangement does not work properly. The bug is that this should not be possible to build at all.

Offline Freahk

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Re: vertical junctions
« Reply #8 on: February 09, 2020, 07:49:25 PM »
obviously it should not be possible to buid that "vertical junction" construct at all.

You just need some glasses to read the small text.

Offline prissi

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Re: vertical junctions
« Reply #9 on: February 10, 2020, 03:46:34 AM »
Ok, so you can lower it down on a bridge (but I fail to remove the bridge and till have the junction). There is also a much simpler way to make a vertical junction:

like image 1&2, end an elevated way on a downward slope, make the elevated way straight, but instead building a bridge, just build an elevated way on the slope below the straight elevated way.

I could also try to catch that, but then many advanced constructs using elevated way may be much harder to build. Also it requires conscious effort, and cannot be done accidentally.

(I have done a fix, to forbid your way of doing it, but I decided to not incorporate it. This is clearly there be eleves territory you are entering, and hence unsupported.)

Offline Freahk

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Re: vertical junctions
« Reply #10 on: February 10, 2020, 10:08:31 AM »
I really don't know what kind of advanced constructs would require such a bug to work.
Generally (I know there ich no such generality in the code) we schould check for the actual way shape above and below when building or changing elevated ways.

Offline prissi

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Re: vertical junctions
« Reply #11 on: February 11, 2020, 12:26:32 AM »
In principle I must also forbid the straighten of the elevated way as the first step. Also elevated way (especially when you need to combine them with bridges) are already very difficult to stack. So forbidding too much freedom there makes it even less fun to make constructions with them. And this easter egg you did is in for almost 12 years, and it does not even cause any crash or bug. So I leave it working, ike the vertical tunnel entries you could build in older version too.