Realistic Fluids Simulation

Realistic Fluids

Live-simulated water, lava and slime for Minecraft. These fluids actually flow, splash, stick and react to each other.

Realistic Fluids adds particle-based fluids that look like the well-known Blender fluid renders. Vanilla water and lava are not replaced. The realistic fluids only appear where *you* place them with the special buckets or spring blocks.

Features

Water

• Real fluid simulation. Water collides with blocks, bounces off them, runs over edges and fills basins and caves all the way down.
• Hard impacts, like the foot of a waterfall, spray in all directions and leave white foam.
• The water has a smooth, closed surface with refraction, depth colouring, reflections, sun glint and foam.
• You can swim in it. From 0.5 blocks deep it works like normal water. Jumping in causes no fall damage, flowing water drags you along, and there is a proper underwater view.
• Players, animals, boats and minecarts push the water aside.

Lava

• Lava is thick and slow. It creeps down stairs as a glowing tongue instead of splashing.
• It glows by itself. Thin flows and edges cool down to dark red.
• Lava + water: the water boils away in clouds of steam. The lava is quenched and hardens into real basalt blocks.
• It burns you like vanilla lava. Fire Resistance protects you.
• Slime that touches lava burns away.

Slime

• Slime is a green, glossy gel that holds together.
• It is sticky. Throw it at a wall or ceiling and it clings there, then slowly oozes down.
• It is bouncy for players. If you fall into slime, it throws you back up like a slime block and you take no fall damage.
• Walking through slime slows you down.

Items and blocks

• Pour buckets (water, lava, slime): hold right-click to pour a stream. Sneak + right-click throws a big splash.
• Block buckets (water, lava, slime): these work like a normal bucket. Right-click a block to place one block's worth of fluid.
• Spring: a block that emits fluid forever, perfect for waterfalls.
• Right-click with an empty hand to set the strength (1–5).
• Right-click with any realistic bucket to switch between water, lava and slime.
• Power it with redstone to switch it off.
• Drain: a block that swallows any realistic fluid that touches it.
• All buckets are infinite. Everything is craftable and has its own creative tab.

In-game settings
Press O (rebindable) or type /realisticfluids menu to open the settings screen. It has these options:

• quality preset (Low / Medium / High / Ultra)
• screen-space reflections
• water murkiness
• sounds
• splash strength
• gravity
• simulation distance
• CPU threads

Other commands:

• /realisticfluids clear removes all realistic fluids on your client.
• /realisticfluids stats shows the particle count and timings.
• /realisticfluids quality <low|medium|high|ultra> sets the quality preset directly.

Performance
Performance was the top priority:

• The simulation runs next to the game on its own threads. The game and render thread never wait for it.
• Resting fluid goes to sleep and costs almost nothing. A resting lake of 357,000 particles needs about 2.4 ms per step on 6 threads.
• Only particles that actually moved are sent to the graphics card.
• There is no particle limit. If a huge amount of fluid moves at once, the fluid runs in slow motion while your FPS stay stable.

Good to know

• Fluids are simulated on each client and are not saved when you leave the world or change dimension. Springs keep running.
• Multiplayer: install the mod on the server and on every client. Players see each other's fluids. Each client simulates on its own, so small details can differ between players.
• Tested with the vanilla graphics settings "Fancy" and "Fabulous!". Sodium is untested. Iris shader packs are not supported.
• Only players interact with the fluids (swimming, burning, bouncing). Mobs are not affected.
• The game rule realisticLavaSolidifies (default true) controls whether realistic lava may create basalt blocks.
• Settings are stored in config/realisticfluids.json.

Recipes

• Realistic Water Bucket (Pour): bucket + prismarine crystals + prismarine shard
• Realistic Lava Bucket (Pour): bucket + magma block + blaze powder
• Realistic Slime Bucket (Pour): bucket + 2 slime balls
• Block buckets: put a pour bucket into the crafting grid to get the block bucket, and the other way round.
• Spring: stone bricks, prismarine shards and a Realistic Water Bucket
• Drain (×2): iron bars above a hopper

Requirements

• Minecraft 1.21.1
• Fabric Loader 0.16 or newer
• Fabric API
• Java 21