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An explosion is a physical event in the Minecraft world, caused by a primed TNT, a creeper, or a fireball launched by Ghasts. An explosion can destroy nearby blocks, propel and damage nearby entities, and start fire.

Properties

  • Position. A TNT explosion happens at the center of a primed TNT, which is a 0.98*0.98*0.98 cube.
  • Power. Power of an explosion determines its blast radius. TNT explosion has 4 power, creeper explosion has 3, fireball explosion has 1.
  • Ability to generate fire. Currently only fireball explosion can start fire.
ExplosionRay

Explosion rays

Process

Destroying blocks

  • Start linearly in the direction from the explosion point to each of 1352 points that uniformly distributed on the surface of a cube centered at the explosion with an edge length of 2.
  • Let blast force on each line equal the explosion power multiplied by a random number in [0.7, 1.3].
  • Check current block every step of 0.3. A non-air block absorbs (blockResistance / 5 + 0.3) * step of the blast force; if the blast force is not completely absorbed, the block is destroyed (air blocks can also be marked as destroyed).
  • The blast force is attenuated by step * 0.75 each step, if the blast force is completely absorbed or attenuated, perform the same process on the next line.

The maximum travel distance in the air of a TNT explosion is 6.9, 5.1 for a creeper explosion, and 1.5 for a fireball explosion. For example, a TNT explosion can destroy a torch 7 blocks away. The minimum block resistance required to absorb maximum blast force of TNT explosion (with at least attenuation of 2 steps) is 77.67, 63.5 of creeper explosion, 20.17 of fireball explosion. So water, stationary lava, obsidian, and bedrock are always indestructible, and furnaces and less resistant blocks can be destroyed by fireballs.

Destroyed blocks have 30% chance of being dropped as items.

Interaction with entities

Define attenuation as the ratio of distance from explosion to the blast radius that equals 2 * power.

  • For each entity where attenuation is less than 1, let impact equal (1 - attenuation) * exposure.
  • Try to apply (impact * impact + impact) * 4 * radius + 1 damage to the entity, and propel the entity so that its velocity increases by impact in the direction from explosion to the entity.

As a result, entities will always get at least 1 damage if they are within blast radius, regardless of explosion exposure.

TNTAABB

Primed TNT AABB

Calculation of explosion exposure

Explosion exposure is the ratio of visible sample points to all sample points drawn uniformly from the axis-aligned bounding box (AABB) of the affected entity. Point visibility is determined with ray tracing from the explosion point to sample points. Details on the sampling method and ray tracing are beyond the scope of this article. The spacing of sample points of a primed TNT is 1/2.96.

AABB sampling error results in directional asymmetry of propulsion. For example, a typical TNT cannon has maximum range in the west direction partly because the sampled AABB of a primed TNT has largest exposure in that direction.

Causing fire

If the explosion has the ability, it will randomly start fire in 1/3 of all destroyed air blocks that are above opaque blocks.

Block Resistance

The data below is pulled from a running instance of Minecraft (beta 1.3).

Block Name Block Resistance
Bedrock 18,000,000
Obsidian 6,000
Lava source block 500
Water source block 500
Water 500
Brick 30
Cobblestone 30
Diamond Block 30
Gold Block 30
Iron Block 30
Jukebox 30
Moss Stone 30
Cobblestone Stairs 30
Double Slab 30
Slab 30
Stone 30
Iron Door 25
Mob Spawner 25
Dispenser 17.5
Furnace 17.5
Burning Furnace 17.5
Coal ore 15
Diamond Ore 15
Wooden Door 15
Fence 15
Gold ore 15
Iron ore 15
Lapis Lazuli Block 15
Block Name Block Resistance
Lapis Lazuli Ore 15
Glowing Redstone Ore 15
Redstone Ore 15
Wooden Stairs 15
Wooden Plank 15
Chest 12.5
Workbench 12.5
Wood 10
Bookshelf 7.5
Jack-O-Lantern 5
Pumpkin 5
Sign Post 5
Wall Sign 5
Note Block 4
Sandstone 4
Wool 4
Minecart Tracks 3.5
Clay 3
Soil 3
Grass 3
Gravel 3
Sponge 3
Cake 2.5
Dirt 2.5
Ice 2.5
Lever 2.5
Stone Pressure Plate 2.5
Wooden Pressure Plate 2.5
Block Name Block Resistance
Sand 2.5
Soul Sand 2.5
Stone Button 2.5
Cactus 2
Ladder 2
Netherrack 2
Glass 1.5
Glowstone 1.5
Bed 1
Leaves 1
Snow Block 1
Snow 0.5
Crops 0
Red rose 0
Yellow flower 0
Fire 0
Lava 0
Brown Mushroom 0
Red Mushroom 0
Portal 0
Redstone Wire 0
Redstone torch (on or off) 0
Redstone Repeater (on or off) 0
Reed 0
Sapling 0
TNT 0 (will ignite)
Torch 0


Typical blast radii

  • Player kill radii of 1, 2, 4 TNT explosion on the ground with 100% exposure: lowest damage isoline; 0%, 25%, 50%, 75%, 100% armor one hit kill isolines.

KillRadiiGrenade1 KillRadiiGrenade2 KillRadiiGrenade4

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