# 2. Materials

## Adding the Fluid Interaction Material Function to your water material

To preview this, open up the **M\_Water** Material.

<div align="center"><img src="/files/-MkATnM_rul8ZEHMc8jG" alt=""></div>

Within the Material you will see two **MF\_FluidInteraction** Material Functions.&#x20;

<div align="center"><img src="/files/-MkAUNv8En37rCC3HHAX" alt=""></div>

They use Material Attributes inputs so make sure to create your Material with a **Make/Break Material Attributes Node**. You should also consider enabling **Use Material Attributes** from the *Details Panel* of the Material you wish to add the fluid sim to.

<div align="left"><img src="/files/-MkAVl2YHGdKAVofA3R9" alt=""></div>

You will want to hook up your Render Targets to this node so make sure you use the same in the set. If you would like to have more simulations, you just need another **MF\_FluidInteractions** in your Material. This one currently uses two.

![](/files/-MkAXc1QLTEgFyQrUlZq)

{% hint style="warning" %}
**NOTE: The more Fluid Interaction Material Functions you have in your Material, the more expensive it will be. It's best to stick with just one. In some special use cases you can have more.**
{% endhint %}

You can offset the UV of the fluid interaction and also change the Displacement Intensity.\
**Displacement Intensity** is set to 15 by default in the preview.


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