TNT Logic - Realistic Explosion Physics

    

Blow out the support and the building comes down.

You know the sight: you blow up the bottom of a tower and the rest of it just hangs there in the air. This mod fixes that.

After every explosion it looks at what is left, works out what is still standing on something, and lets everything else come down as falling blocks. Take out the base of a tower and the whole thing topples. Blow up a bridge pillar and the middle drops out. Hit a tree at the trunk and it goes down, leaves and all.

The explosion itself stays the same - you get exactly the vanilla crater. Everything the mod does happens after it.

Side: Client & Server  •  Works with: Fabric, Forge, NeoForge

  

  

Version 2 is a rewrite of the collapse logic. The first version was great fun to blow things up with, but it could be rough on a world you actually care about. This one keeps the destruction and takes away the nasty surprises.

• Your items stay yours. Chests, barrels, shulker boxes, furnaces, hoppers and other containers never lose what's inside them, whatever happens to the building around them.
• TNT mining is safe again. A blast deep underground only checks what can really fall, so it doesn't lag, and a cave ceiling won't come down on your head. At most a few blocks crumble right above the crater. The same goes for the underside of floating islands.
• Bedrock holds. Anything hanging from bedrock or another unbreakable block stays where it is.
• Harmless explosions stay harmless. Wind charges, and creepers with mobGriefing turned off, don't move a single block.
• There's a limit. At most 2500 blocks fall per explosion (you can change that). Anything over the limit just crumbles away instead of flooding the ground with thousands of items.
• Huge floating builds are left alone on purpose. A giant sky base on a single pillar won't drop thousands of blocks at once.
• Updating is painless. If your config still has the old STAY default from 1.x, it switches to the new FALL default once. If you set STAY yourself after that, the mod keeps it.
• It works the same everywhere - Fabric, Forge and NeoForge, with the same options and defaults.

When TNT goes off, the mod checks the blocks around the crater, together with the building standing above it, and asks one question: does this block still rest on something? The ones that don't start to fall.

They don't just drop straight down, either. Blocks tip away from the blast and spread out as they fall, and the higher they start, the further they go. A tower ends up as a pile of rubble on the ground instead of a new column right next to the old one.

A few examples of what to expect:

If you blow up…	…this happens
The base of a tall tower	The whole tower falls, top included
A spot next to an intact house	A crater and a few loose blocks - the house stays up
The middle pillar of a bridge	A gap opens, and both ends stay on their abutments
The only pillar under an overhang	The overhang comes down completely
The bottom of a long, thick wall	Everything above the gap falls, with clean edges - no floating bridges, no thin pillars left behind
A tree trunk	The tree falls, leaves and all; the tree next to it stays
A room 15 blocks underground	You get a small cave, and the house on the surface doesn't notice
Several TNT at once under foundations	The house comes down and nothing is left floating

A block stays up only if it rests, directly or through other blocks, on solid ground or on something unbreakable like bedrock. And not every block can carry the same weight:

Support	Carries roughly
Full block (stone, planks, dirt…)	35 blocks
Wall	15 blocks
Slab, stairs and other non-full blocks	10 blocks
Fence	6 blocks
Iron bars	5 blocks
Glass	3 blocks

So a big floor sitting on one fence post won't survive losing everything else under it.

Some blocks never hold anything up at all:

• Torches, flowers, grass, carpets, signs - anything you can walk through. A beam resting on a torch falls just like one resting on thin air.
• Leaves. A house that happens to touch a tree isn't held up by it.
• Containers. A chest under the floor won't keep the house standing.

Containers never carry a building, and they never lose their contents. What happens to one that has lost its support is up to you, with containerCollapseMode:

Mode	What happens
FALL (default)	It falls with the building, items still inside
STAY	It stays where it was, contents untouched
BREAK	It breaks and drops its items (a shulker box keeps them inside, like in vanilla)

A container hit directly by the explosion behaves exactly like in vanilla.

• Beds, doors, tall flowers and extended pistons don't land as half a block. They break whole and drop exactly one item.
• A falling block that lands on a slab, stairs, fence, wall, torch, lantern, campfire, flower, carpet, snow layer, glass or leaves crushes it and takes its place. Nothing gets duplicated.
• Glass close to the blast shatters.

• Forge / NeoForge: config/tntlogic-common.toml
• Fabric: config/tntlogic.json

Option	Default	What it does
maxFallingBlocksPerExplosion	2500	How many blocks can fall per explosion (10-10000)
enableLargeStructuresCollapse	true	Falling blocks spread to the sides; turn off and they fall straight down
physicsScatteringForce	0.2	How far blocks are thrown to the sides (0.0-2.0)
instabilityRadius	5	How far from the crater the support is checked (1-15)
maxCollapseRadius	32	How far the collapse can reach for tall buildings (1-64)
scanHeightAboveExplosion	16	How many blocks above the crater are checked (4-64)
looseBlockChance	0.35	Chance that a block left hanging right over crater falls. 0 turns it off
dropExcessBlocksAsItems	false	Blocks over limit drop as items instead of crumbling. Containers always drop contents
containerCollapseMode	FALL	FALL, STAY or BREAK - see Containers section

With this mod, TNT stops being just a mining tool - one blast in the wrong place can bring a whole building down. Be careful with it, and back up your world before you try anything big.

If you want it to feel even more real, treat TNT as something rare and valuable. With what it can do now, it might even deserve a harder crafting recipe. Use it wisely, or watch your world crumble.

Found a bug or have an idea? Discord is the fastest way to reach me. Feel free to also check out and subscribe to my YouTube channel!