In this lesson, you will learn how to manipulate the shape, density, and coverage of volumetric clouds by injecting custom noise patterns into the Unreal Engine Cloud Material.
While the default Volumetric Cloud component provides a solid baseline, "sculpting" refers to using material expressions to mask and distort the volume. Instead of relying solely on global parameters, we can use a Volumetric Cloud Material to inject unique noise behaviors that define where clouds grow and where they thin out.
Using Texture-Based Noise for Shaping
The core idea is to treat the cloud's density as a variable influenced by a 3D texture. By layering different noise patterns—specifically Perlin or Worley noise—you can emulate the natural "billowing" effect of cumulus clouds.
To implement this, navigate to your Volumetric Cloud Material and utilize the CloudSampleAttribute node. You can multiply your noise texture output against the Density input. Here is a basic implementation of how to define that density flow:
// Example of blending noise for cloud shaping
float3 LocalPos = GetWorldPosition();
float3 CloudNoise = TextureSample(CloudNoiseTexture, LocalPos * ScaleFactor);
float FinalDensity = saturate(CloudNoise - BaseThreshold) * CoverageMultiplier;
Controlling Coverage and Detail
By using a Texture Object containing a 3D noise map, you can modulate the "Density" attribute dynamically. Use a Scalar Parameter linked to a Subtract node before passing your noise into the density pin; this acts as your "coverage slider." When you increase this value, you are effectively "sculpting" away the thinner edges of the clouds, creating sharper, more defined horizons.
To add fine detail, use a second, smaller-scale noise texture multiplied by a lower intensity. This "high-frequency" noise breaks up the silhouette of the clouds, preventing them from looking like uniform blobs and giving them the wispy, fractal edges required for high visual fidelity.
Key Takeaway: By multiplying layered noise textures against the density attribute within the Volumetric Cloud material, you can procedurally sculpt cloud shapes, density, and coverage to move beyond basic presets.