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MC-129623

Maps get filled with gray areas instead of revealing terrain

Resolution note

In general upgrading from a snapshot is not supported and might not work as expected. So far this issue has only appeared when a world has been opened in a snapshot before.

Please comment and if possible provide your world (not upgraded) if you are experiencing this issue for a world which has not been opened in a snapshot before.

The bug

When using a map, it gets filled with gray areas instead of showing terrain. Previously revealed areas are being filled in gray too.

Related issues

MC-129627 Maps do not work on snapshot 18w20a MC-129633 Map Bug MC-129658 Strange gray path draws in the map where the player goes MC-129761 Maps appear grey and only display updated blocks MC-129774 Maps load improperly MC-129802 Map grey out explored areas. MC-129818 Karte in der Hand: Umgebung wird mit grauer Farbe eingezeichnet MC-129820 aktualisieren von Karten in Welten aus alten Versionen lässt diese grau werden MC-129869 Maps corrupted by 18w20, show all gray MC-129969 Updating map MC-129988 Maps rendering blank when exploring MC-130071 Map in overworld showing mostly gray MC-130155 Maps don't work. MC-130359 Maps Error : gray time! MC-130560 Item Map does not show already rendered areas. MC-130663 Maps don't work correctly MC-130843 Map is gray MC-130869 After 18w16а appears in another place, with a different level and different inventory MC-130888 Grass is grey on maps MC-131042 Maps don't work MC-131049 Map MC-131231 Map MC-131265 Maps MC-131718 Maps revealing gray

Attachments

Comments

migrated
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migrated

Was the world converted to 18w20c from an earlier snapshot? If it was, that could be related, as old world generation seems to have other effects as well.

violine1101

The cause for this is that while drawing the map, some of the top layers are skipped for some reason. When destroying and placing a block on the surface, it appears on the map correctly. There probably is some limit in the code that draws the map.

(See also MC-129500 for examples where the background is not completely gray.)

migrated

AH and I think I have found the cause of this bug

The recent world format change modified something relating to height maps for lighting calculations. The maps appear to use the value taken from here, but the world generated before 18w20 does not have those tables properly generated by the updating code (and, presumably, they default to 65).

I don't think this is related to MC-129500, at least not directly. That one could be just an off-by-one error.

Here is an experiment confirming my theory: everything gets back to normal after placing a torch in the chunk, forcing an update of the light/height map.

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migrated

This seems to happen in 18w20c with worlds that had been created in older snapshots, but NOT in worlds created in 18w20c. I could not get the above mentioned torch trick to work.

 

michael

Is this actually happening in situation where no previous snapshots are involved? I can't reproduce it and if it only happens in worlds that got "corrupted" in a snapshot, we won't fix that. If on the other hand there are situations where it happens with older worlds from published (non-snapshot) versions of Minecraft, please re-open this issue.

migrated

Relates to MC-129725 as the old blocks are simply being threated as “not there” for both light and maps.

migrated

This bug has been fixed in 1.13-pre3.

migrated

michael

Confirmed

Minecraft 18w20a, Minecraft 18w20b, Minecraft 18w20c

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