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UE5 Dynamic Liquid Shader: Tutorial

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Corentin Demougeot edited this page Jun 25, 2023 · 18 revisions

Prerequisites

Before using the liquid shader in Unreal Engine, there are some important points you need to consider:

  • The liquid shader works with Static Mesh Actor or Static Mesh Component.
  • The mesh that receives the liquid shader needs to be closed.
  • Ensure that your mesh's normal direction is correct.

In Unreal:

  • Download the Liquid Shader plugin from here
  • Create a Plugins folder in your project root directory and copy/paste the plugin folder into it.
  • In Unreal Engine, go to Edit -> Plugins in the top left panel of the main editor window and enable the UTC_LiquidShader plugin.
  • Go to Edit -> Project Settings in the top left panel of the main editor window, search for Substrate materials (Experimental), and enable it.
  • Reload the editor.

Setting up the Actor Component

For a Static Mesh Actor

Select the Static Mesh Actor you want to add the liquid shader to. In the detail panel at the root, add the Liquid Shader Component:

For a Static Mesh Component in a BP

You can find a BP already set up in ../Plugins/UTC_LiquidShader/Content/BP/BP_LiquidActor

Otherwise, create your BP as usual. Add your Static Mesh and the Liquid Shader Component to the BP.

Go to the Class Settings panel on the BP top bar. In the Implemented Interfaces section of the right detail panel under the Interfaces section, add the UTC LSInterface.

In the left panel My Blueprint, under the INTERFACES -> Liquid Shader category, right-click on the Request Static Mesh Component interface and select Implement Event.

Drag and drop the Liquid Shader Component onto the graph and search for Set LS Static Mesh Component with the component selected.

Connect the Request Static Mesh Component Event execution pin to the Set LS Static Mesh Component node and connect your Static Mesh Component to the LS Static Mesh Component pin.

Actor Component Parameters

Global

  • Liquid Material Instance: Set your main Liquid Shader Instance here. The default instance has already been set up and can be found in ../Plugins/UTC_LiquidShader/Content/Library/MI/MI_Liquid. (Must be the same instance set to the mesh)
  • Include Materials: Sometimes you may need to include materials to close the mesh, for example with the bottle, where the cork closes the mesh but it's not a liquid shader's instance. Add the cork material to this list.

Waves

  • Waves Intensity: The main parameter to modify the wave sensitivity. It is recommended to keep it at 1.
  • Waves Rotation Sensibility: The parameter to modify the wave sensitivity during rotation. Modify this parameter instead of the first one.
  • Waves Offset Sensibility: The parameter to modify the wave sensitivity during translation. Modify this parameter instead of the first one.
  • Viscosity: Modify the wave speed.

Liquid Adaptation

  • Show Voxel: If you want to debug the voxel size. (has a high performance cost)
  • Voxel Factor: Modify the voxel size.
  • Adaptation Speed Scale: A higher value hides the liquid's adaptation and removes the compression effect but could create stuttering for slow rotation. This speed is relative to the wave sensitivity parameters, so remember to adjust it if you modify those.

Optimization

  • Generate Cap: Enable/Disable cap
  • Clean Up Cap: Enable/ Disable clean-up pass for the cap
  • Liquid Adaptation: Enable/Disable liquid adaptation. If your object is uniform with a centered pivot point, you can disable it (for example, a sphere).

Shader Parameters

These are the names of the different parts of the shader mask:

Glass Shader

You can find a glass instance already set up at ../Plugins/UTC_LiquidShader/Content/Library/MI/MI_Glass.

There are classic parameters to modify the color, specularity, normal, and roughness to add details and modify the refraction. Note that the Start Refraction Offset parameter is useful to remove internal refraction (for example, in the case of a cork), but it can be affected by other objects in the scene and needs improvement.

Liquid Shader

The liquid shader instance is actually an instance of the glass shader. You can find a liquid instance already set up at ../Plugins/UTC_LiquidShader/Content/Library/MI/MI_Liquid.

For clarity, I will not cover all the liquid parameters, but I will highlight the most important ones for me:

  • Cap deformation intensity: Under the Liquid – Cap Mask category, this creates deformation on the liquid side.
  • Side cap size: Under the Liquid – Cap Mask category, this controls the size of the front and back side caps.
  • Liquid Offset: Under the Liquid – Position category, this controls the liquid's position relative to the object's pivot point
  • Debug Bubbles: Under the Bubbles category, the bubbles' positions require runtime parameters. If you want to see an approximate representation of how they will render, set this Boolean to "true" (Don't forget to disable it before playing).

All parameters set under the "Value Set by Component" category cannot be modified.

Limitations & Troubleshooting

Limitations:

  • Needs GPU support (Not tested on APU).
  • Display bug between Substrate and 1000 series GPUs.
  • Max Render Targets size: 2048 x 2048px.
  • Max object material slots: 16.

Troubleshooting:

Don't hesitate to give me feedback !

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