Placement Table[]
| Blocks destroyed on extention[n 1] | Blocks destroyed on retraction | Blocks that stop extention[n 2] | Blocks not destroyed | |
|---|---|---|---|---|
| Upwards-facing pistons |
|
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| Sideways-facing pistons |
|
|
||
| Sideways-facing pistons |
|
N/A |
- pressure plates require the block below to have a rim (e.g. hopper) or center point on top (e.g. glass pane)
- rails require the block below to have a rim
- banners and cakes require the supporting block to be a solid material (materials should probably be documented somewhere)
- bells and levers require the supporting face to be "full"
- carpet just needs to be above anything but air
- lanterns need a center point on top (if place on top) or below (if placed below) -- for example a lantern can hang below a down-pointing hopper but can't be placed on top
- redstone dust requires a full face below, but is also hardcoded to allow hoppers
The "rim" and "center point on top" are apparently well-defined in-game predicates; for example, the center point is a 2x2 center square on the hitbox (not visual box) assuming the surface is a 16x16 square grid. Quoting tryashtar on the "rim", "It's a predicate that is created specifically by removing the entire center section from a full cube, leaving only the, well, rim".
In references to other placement quirks (by tryashtar):
Sea pickles just check if the below block has a non-empty upward face
Not a block but item frames are really interesting, they can be placed anywhere that doesn't intersect with their hitbox (and support block material must be solid (or a repeater/comparator))
By the same person, on leaves' exceptional behavior:
Leaves are considered to have faces that are "full" but not "sturdy"
Rigid blocks (blocks that require a rim):
- Redstone Repeater
- Redstone Comparator
- Rail
- Powered Rail
- Detector Rail
- Activator Rail
- Pressure Plates[n 1]
Center blocks (blocks that require a center):
- Torch (floor only)
- Soul Fire Torch (floor only)
- Redstone Torch (floor only)
- Lantern
- Soul Fire Lantern
- Pressure Plates[n 2]
Blocks that require a sturdy face: