Issue:
When walking from a top trapdoor onto a scaffolding block the player just falls right through the scaffolding as if it wasn’t there. This happens with all trapdoors, including iron.
Expectation:
Walking from trapdoor to scaffolding behaves like every other exactly full height block. Allowing the player to freely walk onto the scaffolding.
Recreate:
1. Place a top trapdoor.
2. Place scaffolding next to the trapdoor.
3. Walk off the trapdoor onto the scaffolding.
4. Observe that you phase right through the scaffolding.
Fixed in 1.16.0.
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Comments 2
This might be fixed by the fix for MCPE-13451 in 1.15.0.51 beta.
Confirmed in Windows 10 1.14.0.30.
Starting with a structure like this:
[media]Stand on the scaffolding block between the quartz and the trapdoor. Note your Y coordinate in the coordinates display. In this flat world, it is 7.
[media]Now walk to the middle of the trapdoor. Note that your Y coordinate is now 1 lower (6 in this case).
[media]What's happening is that the coordinates displayed in the HUD are always rounded down to the nearest integer. Scaffolding is a full-size block, so when standing on it your Y coordinate will correspond to the air block above it. However, the top side of a top trap door is a tiny bit below the top of its block frame, so when you're standing on it your Y coordinate (as displayed) will be slightly lower than the top of the block frame, so it gets rounded down in the display. This tells you that your actual, unrounded Y position is slightly less than 7.
When you walk from the trap door onto the next scaffolding block, you do not jump up onto the scaffolding because scaffolding can be entered from the side. Thus, you will enter the scaffolding block that you think you are above, and since there's no support beneath it, you fall through it. I didn't test this, but I believe that if you jump from the trap door onto the scaffolding, the extra height will cause you to land on top of it and you won't fall.
The fact that a trapdoor's face doesn't perfectly align with the block frame it's in was, I believe, an adjustment made to solve a different problem, though I don't remember which one.