Round end roads are rendered over cycleway

[Florimondable]

Updated: Summary of this issue

Round ends of bridges are rendered over cycleways, see https://www.cyclosm.org/#map=17/48.85438/2.34576/cyclosm.

Possible solutions:

• Having separate layers for roads and cycleways and interleave them > does not work since we don't want a regular cycleway below a bridge road to be drawn on top of it.
• Switching bridge and regular roads layer > does not work since we don't want the regular roads to be on top of bridges in general case.

No further solution at this point :/

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Petit pont or Pont St Michel, Paris

[Bibi56]

This is probably valid for any wire display (foot ways here : https://www.cyclosm.org/#map=19/47.79712/-3.48149/cyclosm, https://www.cyclosm.org/#map=18/47.79712/-3.48149/cyclosm): roads should be displayed first.

[Phyks]

Quite related issue with motorways trunk as well: https://www.cyclosm.org/#map=18/47.04951/-1.63764/cyclosm.

[Bibi56]

@Phyks You're right, the road network should be displayed in reverse importance order, motorways first, path last.

[Florimondable]

@Phyks You're right, the road network should be displayed in reverse importance order, motorways first, path last.

Well no, as we do a cycle map, cycleway must be over other roads :).
And we did that on purpose, we had the case with that cycleway hided by the primary road next to it
https://www.cyclosm.org/#map=19/48.84799/2.27604/cyclosm

Though other roads (may be not path) should be render from primary to track)

[Bibi56]

@Florimondable

Well no, as we do a cycle map, cycleway must be over other roads :).

That's why you have to display the other network first to display cycle ways on top.

[Phyks]

Not sure what happened but #154 (comment) is now fixed on its own.

Concerning #154 (comment), we want cycle infrastructure to always be on top. What was misleading is that the footway was under the main highway whereas the cycleway was on top, this is now fixed (not yet in production) with both being on top of the main highway.

Remaining issue is the original one (#154 (comment)), located at https://www.cyclosm.org/#map=18/48.85436/2.34440/cyclosm.

Pont Saint-Michel being a bridge, there is not much possibility to make it go underneath the cycleway with the current layers. Quick fix could be to remove the round ending for bridges? Otherwise, this is quite the same issue as #136 and the only fix I can think of at the moment is moving the cycleways to dedicated layers.

[Bibi56]

Quick fix could be to remove the round ending for bridges?

Sounds good to me. I don't see any side effect.

[Florimondable]

I think there is possible side effects, but worth a try.

[Phyks]

Not easy to fix, no line-cap: round is really horrible:

Openstreetmap-carto has this quite enigmatic comment https://github.com/gravitystorm/openstreetmap-carto/blob/master/roads.mss#L1107-L1108 which we might dig into. They don't have this issue in the render, so they probably do it right https://www.openstreetmap.org/#map=18/48.85327/2.34692&layers=N.

[Florimondable]

Because path are rendered under main highway osm.org don't have the issue we see in your try.

[Florimondable]

I think regular path (not bicycle=designated) can be rendered under main highway in CyclOSM too.

[Bibi56]

You seem to render bridges before cycle ways.

If you render bridges after, it may be correct: render normal network (outside bridges) then render bridges but this includes cycleways on bridges, it may be difficult to do.

I get one part of the comment you mentioned (if you render something with transparency several times it changes the transparency, that's why it "glows"), not the second part (why changing line-cap forces multiple rendering, I guess it has to do with the Mapnik rendering engine, maybe the issue is solved now).

If you look at the cycling map on osm.org, https://www.openstreetmap.org/#map=18/48.85327/2.34625&layers=CN, they seem to display the cycleways last with transparency.
That doesn't take into account that the way is under the bridge but seems to be a good compromise.

It took me some time to see what was ugly, yes the Petit-Pont. But I don't known how the path can be on the bridge at one side and under on the other end. Sure the way is just a line, not a closed area but if you look at the imagery, the path should be perpendicular to the bridge and therefore you shouldn't have this ugly effect.

At Pont Saint-Michel you have a road bridge (layer=1) displayed after a foot bridge. Another edge case!

[Phyks]

You seem to render bridges before cycle ways.

We should not, bridges are in this layer while the regular cycleways are on this layer below.

If you look at the cycling map on osm.org, https://www.openstreetmap.org/#map=18/48.85327/2.34625&layers=CN, they seem to display the cycleways last with transparency.
That doesn't take into account that the way is under the bridge but seems to be a good compromise.

They however seem to have similar issues on the next bridge :) https://www.openstreetmap.org/#map=18/48.85390/2.34429&layers=CN

[Florimondable]

link to #192