# Building Grass, Physical Mateirals & Adjustements

{% hint style="info" %}
[Please see this Unreal Documentation link if you don't know how to use the Grass node. The Landscape Physical Material Output works in the same way. ](https://docs.unrealengine.com/4.27/en-US/BuildingWorlds/OpenWorldTools/Grass/QuickStart/)
{% endhint %}

Editing the Master material is required to use Physical Materials and Grass. Click the MASTER button at the bottom of the interface to open the Master.

In this example, the grass is on the Base Layer, the Dirt on the Sub-Layer 1 and rocks on the Sub-Layer 2.

![](https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FENjBfFQ2m2sWApaFrUgS%2Fimage.png?alt=media\&token=94c75247-33e2-4cb6-9699-e654ce7ebf70)

Here you'll find all your layers as well as the Grass and Landscape Physical Material Outputs.&#x20;

To use them, simply add your grass types/physical materials, plug your desired Sub-layers, and that's it !

![Applying grass only on the base layer](https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FosakgqDMlJICX3yeMRhu%2Fimage.png?alt=media\&token=12930861-a8c0-4a58-a6cb-3dbfb38fb78f)

![Grass type only applied on the Base Layer](https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FBYsuLgml5dAkiLTC9ZdA%2Fimage.png?alt=media\&token=51a6e8af-b7ac-476c-9ba5-ca05742ea6d3)

### Applying the same grass type to multiple Sub-Layers

Simply add the desired layers together before plugging in to the nodes.

![Adding the Sub-Layer 2 and the Base Layer to the nodes. ](https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FEdsr0FOYlsXAuJ7Ax8h5%2Fimage.png?alt=media\&token=5245aa73-5b6b-45fc-9134-4c6480e8fe5f)

![Grass on the base layer + Sub-Layer 2](https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FhqPW2vvEzl2OXFXqK646%2Fimage.png?alt=media\&token=6abe2ef5-0bc8-4b5c-9c13-fd3def1e52d4)

If you want to remove all grass values form a specific area, you can paint as Non-Weight Blended the ERASE-GRASS layer.

<figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FVKSOQnV562bRRhYh2V2m%2Fimage.png?alt=media&#x26;token=a055b149-648b-4206-93bf-b880008aeba2" alt=""><figcaption></figcaption></figure>

##

## Grass Adjustements

The Grass tab allows to tweak the Grass Map Values associated with the Sub-Layer.

The examples below, shown in LOOKDEV, shows how the Grass Adjustements affect the rendering of the Grass and a few tips.



### Grass-Only Mode

The flower are applied with the Sub-Layer 2.

As the Sub-Layer 2 is only used for applying the flowers, its material does not need to be rendered.

If a Sub-Layer does need to render the Material, the Grass Only toggle can be enabled.

<figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FWMg9FKwvSoCJXODXdM91%2Fimage.png?alt=media&#x26;token=f68f31c7-db0d-4454-ad9d-9d66a95ef96d" alt=""><figcaption><p>When toggled, the Grass Only mode does not render the Material.</p></figcaption></figure>

<div><figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2F5jHpDWNleUyyCZHe0TWy%2Fimage.png?alt=media&#x26;token=a4ea3087-641f-42af-bd41-30f7f8e7288a" alt=""><figcaption><p>Grass-Only Mode Disabled.<br>Notice the Black spots being the material of the Sub-Layer 2.</p></figcaption></figure> <figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FfMCXPUkyyxVtiwMcFq3o%2Fimage.png?alt=media&#x26;token=35598ad6-8595-4ebc-bd2d-481856636f75" alt=""><figcaption><p>Grass-Only Mode Enabled.<br>The Sub-Layer 2 dosen't render its Material.</p></figcaption></figure></div>

### Passtrough Mode

If enabled, the Sub-Layer will render its Grass Meshes on top of the previous ones.

This can be especially useful for applying flowers on top of the grass, instead of just replacing it.

<div><figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FU81d3I1X6z043zeYtPct%2Fimage.png?alt=media&#x26;token=fc3c06ee-63c4-4829-851e-d4e3cdcb1384" alt=""><figcaption><p>Passthrough Mode Off. <br>Notice that the flowers REPLACE the grass instead of being on top of them.</p></figcaption></figure> <figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FwEze94zLCrW6GjPBgBFR%2Fimage.png?alt=media&#x26;token=2b0890d9-c0d1-4c8a-ad47-5384727de85c" alt=""><figcaption><p>Passthrough Mode On. <br>Notice that the flowers are rendered ON TOP of the grass.</p></figcaption></figure></div>



The second Sub-Layer is made using a Splatmap multiplied with the Noise forming the grass of the Sub-Layer 1 (Noise of the SBL 2 Linked to the Noise of the SBL that initally applied the grass.)

### Grass Map Adjustements

The Contrast and Force Settings in the Grass Adustement Tab affect how close to the mask map the grass will be applied. Setting a Negative Contrast value will invert the Grass Map.

**Contrast**

<div><figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2F7KC5QjhiOXPnXUU6hMCr%2Fimage.png?alt=media&#x26;token=17493add-b7f1-4ca5-aaf9-756623e0283e" alt=""><figcaption><p>Default Contrast, Default Force</p></figcaption></figure> <figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FBtVZah2MQR81EanXGNVm%2Fimage.png?alt=media&#x26;token=de8f1024-2f6d-4432-a68a-215bf74c1ee5" alt=""><figcaption><p>100x Contrast</p></figcaption></figure></div>

<figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FRNdNd3G38lHFfSjO3V43%2Fimage.png?alt=media&#x26;token=d06e9ee4-9679-422c-a5b2-df1612c1032d" alt=""><figcaption><p><strong>Negative Contrast</strong>, inverts the Grass Map !</p></figcaption></figure>



**Force**

<div><figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2F7KC5QjhiOXPnXUU6hMCr%2Fimage.png?alt=media&#x26;token=17493add-b7f1-4ca5-aaf9-756623e0283e" alt=""><figcaption><p>Default, with 0 as Contrast and 1 as Force.</p></figcaption></figure> <figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2F5Q5W3n92O6oG6WdO2DBg%2Fimage.png?alt=media&#x26;token=1ac8f16d-f4e0-405b-81d3-db2fdae01572" alt=""><figcaption><p>Default Contrast but with 20 in Force.</p></figcaption></figure></div>



### Breaking Uniformity with Noise

<figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FK6MGrA1t2tpizvXpdP7A%2Fimage.png?alt=media&#x26;token=27586e87-dfd8-469e-b027-d7bfc8ce3dc8" alt=""><figcaption><p>Default Grass Map values, with a high density grass preset to show the map.</p></figcaption></figure>

<figure><img src="https://3422122786-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FKy5lT5JIdDDFDRaA6D4d%2Fuploads%2FHdCdVZZy1Vt6jo1vVjBq%2Fimage.png?alt=media&#x26;token=4afc56d2-2035-4667-aca1-e1720a73aa81" alt=""><figcaption><p>Grass Map, using a Noise to break the uniformity of the map.</p></figcaption></figure>

