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Hydraulic Erosion

Actual water erosion. At compile time it pulls a 2D heightmap out of the field above it, runs tens of thousands of simulated droplets down the slopes, and lets them carve valleys and drop sediment....

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Hydraulic Erosion node

The Hydraulic Erosion node

When to use it

Actual water erosion. At compile time it pulls a 2D heightmap out of the field above it, runs tens of thousands of simulated droplets down the slopes, and lets them carve valleys and drop sediment. At runtime the eroded heights get sampled back into the density.

Pins

Pin Type Description
Density Number The landscape to run water over. It has to be height-based, something like noise minus Position Z.
Pin Type Description
Result Number The same landscape with valleys cut into it and sediment left in the low spots.

Settings

Setting Type Description
Resolution Whole number How fine the grid the water runs on is. Higher picks up narrower valleys, and costs you compile time and memory for it.
World Size Number How much ground the simulation covers, in world units, square. Make it smaller than the area you are actually generating and everything past the edge comes out uneroded.
World Center Vector 2D Where that square sits in the world.
Blend Margin Number How far past the edge the eroded ground fades back into the ground you fed in. Set it to 0 and the two meet in a step, which the mesher renders as a tall vertical wall right around the perimeter. The default is a tenth of World Size; widen it if the join still shows.
Num Droplets Whole number How many droplets get released. Too few and you get scattered scratches instead of a connected drainage pattern. More of them means a longer compile.
Max Droplet Lifetime Whole number How far one droplet is allowed to travel before it gives up. Raise it for long rivers, lower it for short gullies near the peaks.
Erosion Radius Whole number How wide a track each droplet cuts, in grid cells. Wider gives you smooth valleys, narrow gives you sharp channels.
Seed Whole number Changes where the droplets start. Same seed, same rivers, every time.
Inertia Number How much a droplet keeps its heading instead of turning downhill. At 0 it hugs the steepest line and rivers come out kinked; near 1 it coasts straight across dips and barely carves anything.
Sediment Capacity Factor Number How much a fast droplet can carry. Raise it for deeper carving.
Min Sediment Capacity Number The floor on that capacity, so a droplet crawling across a flat does not dump everything it is holding in one spot.
Erode Speed Number How quickly ground is cut away when a droplet has room for more.
Deposit Speed Number How quickly a droplet lets go of what it is carrying once it is overloaded.
Evaporate Speed Number How fast a droplet dries up. Higher gives you short streams near the peaks; lower lets them run all the way to the bottom.
Gravity Number How hard the slope pulls. It sets how much speed a droplet picks up on the way down.
Initial Water Volume Number How much water each droplet starts with.
Initial Speed Number How fast each droplet is already moving when it lands.

Available in Mesh Morpher Graph and Mesh Morpher Studio.