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Before starting this tutorial, read Working with Data to understand Groups, Resource Types, and Prototypes.
This guide walks you through setting up a grass detail pass using the Grass Stamper tool and the Unity/Terrain Detail resource type. By the end you will have a working stamper that fills your terrain with grass driven by mask filters.

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Before you begin

You need:
  • A Unity project with MegaWorld installed.
  • A Unity Terrain in your scene with at least one detail prototype already configured in the Terrain Inspector.

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Step 1 — Create a Grass Stamper

Go to GameObject > Vladislav Tsurikov > Add Grass Stamper. A new Grass Stamper object appears in your Hierarchy. Its Transform scale defaults to (500, 500, 500). Scale it to cover the area you want to fill.

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Step 2 — Add a Group

Select the Grass Stamper in the Hierarchy. In the MegaWorld Window, click Add Type to create a new Group. Rename the Group to something descriptive, for example Grass or Undergrowth.

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Step 3 — Add Terrain Detail prototypes

Inside the Group, click Add Resource and choose Unity/Terrain Detail. Assign a detail prototype that matches one already registered in the Unity Terrain Inspector. Repeat to add multiple detail types to the same Group — each prototype will have its own density and filter settings.

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Step 4 — Configure Spawn Detail Settings

In the prototype settings, expand Spawn Detail Settings:
  • Density — maximum detail count per terrain cell.
  • Use Random Opacity — adds variation so cells at the same filter fitness get different counts, breaking up a uniform look.
  • Failure Rate — randomly zeroes some cells to create natural sparse gaps.

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Step 5 — Add Mask Filters

Each Terrain Detail prototype has its own Mask Filters block. This lets you give every grass type a completely independent placement rule. Common setups:
  • Slope filter — short grass on flat ground, bare dirt on steep slopes.
  • Height filter — wildflowers only in lowland areas.
  • Noise filter — organic cluster patterns.

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Step 6 — Spawn

In the Stamper Tool Controller section, click Spawn. Grass Stamper evaluates each active prototype across all Unity Terrains that intersect the stamper bounds and writes the detail density data.

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Step 7 — Enable Auto Respawn for fast iteration (optional)

Turn on Auto Respawn in the Stamper Tool Controller. Changing any prototype setting — including individual mask filter values — triggers an automatic respawn of just that prototype. You can tune a noise filter on one grass type and see it update immediately without touching the others.

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What’s next

  • Add Object Stamper to the same area to place trees and rocks on top of your grass pass.
  • Use Grass Brush to hand-paint grass in specific spots using the same prototype settings.
  • Use Texture Stamper to paint the underlying terrain texture layer before running a grass pass.
  • Read the full Grass Stamper reference for all settings and behaviors.