Steps to reproduce
Load
(this world has been opened in 1.21.0.20 Preview).
Fly up to Y 130 and watch the platform.
If 8 non-spider mobs spawn, run /kill @e and watch for a while longer.
Expected result
Spiders would not spawn.
Observered
Spiders spawn on the stone where they collide with carpet.
Linked issues
is duplicated by 1
Attachments
Comments 3
This issue is caused by the "MaterialIsSolidBlocking" property, which derives from the internal material type code for the block. For unknown reasons carpet uses a unique material type code (31) instead of using the code for wool (11). If the material type of carpets is changed to match wool it should change all of the material-derived properties automatically, and fix this issue.
Fixing wool carpets would not affect moss carpets, which are set to material type 8 like crops, flowers, vines, etc. Moss carpets should probably be left as they are in order to not make MCPE-155420 worse.
Pressure plates should also block spider spawns due to the same mechanic but do not in the 1.21 preview. Efforts to fix this bug should look at pressure plates too.