Draw an island

Level: beginner · Time: 20 minutes

In this tutorial you'll block out an island by hand, give it natural detail, erode it and surround it with sea.

You'll use: Polygons, fBm, Combine, Warp, Hydraulic Erosion, Thermal Erosion and Sea.

1. Draw the coastline

1. Create a new project and add a Polygons node.
2. Press Tab to switch to the 2D map.
3. Select the node and click Draw polygon in its settings. Click on the map to add corners, and click the first corner (or press Enter) to finish.
4. Drag corners to adjust the shape. Drag an edge's midpoint to add a corner, and Alt+click to delete one.

Each polygon is flat ground at its own height. Falloff sets the width of the slope around it, and Base sets the height of the ground outside every polygon, which is the sea floor.

TIP

Draw a second, smaller polygon inside the first for a plateau. With Overlap set to Later polygons on top, the later one wins.

2. Add natural detail

A drawn shape looks artificial. Break it up:

1. Add a Warp after the Polygons node. Warp pushes the terrain around with smooth noise, bending straight lines into natural ones. Increase Strength until the coastline stops looking drawn.
2. Add an fBm noise node and Combine it with the warped island using Add. Keep the fBm's Height modest (a few hundred metres) so it adds hills without drowning the shape.

3. Erode it

1. Add Hydraulic Erosion after the Combine. View it: valleys branch down to the coast.
2. Add Thermal Erosion after it for scree.

Keep the preview resolution low while you tune. The build will match.

4. Add the sea

1. Add a Sea node after the erosion.
2. Set Sea level so the water meets your coastline. Everything below it that the sea can reach from the world's edges is flooded. Land just above it is worn into beaches (Beach height, Coastal erosion).
3. View Sea's Shallows and Shoreline outputs. They're perfect masks for sand and surf later.

5. Export

Mark Sea's Height output as EXR (or PNG 16 for Unreal), and its Water surface too. Then press Build (Ctrl+B).

Next: From LibreTerrain to Godot adds colour and vegetation and takes the result into a game engine.