Deep dive: how the four Volume Shader presets work
The four presets in the Volume Shader editor are compact lessons in real-time volumetric rendering. Fog Sphere teaches distance fields and density. Twirl Smoke shows how coordinate warping can look volumetric without a full 3D field. Cloud Layer introduces true density accumulation. 3D Fractal pushes ray marching toward procedural surface rendering.
Use this article as a map before opening the presets page. Each preset becomes easier to edit once you know what it is trying to teach.
Quick comparison
| Preset | Core idea | Best lesson | Cost |
|---|---|---|---|
| Fog Sphere | SDF density | Turning distance into fog | Medium |
| Twirl Smoke | 2D noise warp | Motion through coordinates | Low |
| Cloud Layer | 3D noise | Volume accumulation | Medium |
| 3D Fractal | Iterative field | Ray-marched surfaces | High |
Fog Sphere: distance becomes density
Fog Sphere is the best first preset because the logic is visible. A camera ray steps through space. At each point, the shader asks how far the point is from a sphere. That distance becomes density, and density becomes color.
float sdSphere(vec3 p, float r) {
return length(p) - r;
}
float density = clamp(0.7 - sdSphere(p, 0.7), 0.0, 1.0);
fog += density * 0.04;
Change the radius, density multiplier, or step size in the editor. The same shader can feel like mist, plasma, glass, or atmosphere.
Twirl Smoke: cheap motion from warped coordinates
Twirl Smoke uses 2D noise, but it bends the sample coordinates in polar space. The farther a point is from the center, the more the angle turns. This creates a vortex without marching through a full 3D volume.
That makes the preset useful for lightweight backgrounds, loading states, and mobile-friendly shader effects. If performance matters more than physical depth, this pattern is worth remembering.
Cloud Layer: a real density field
Cloud Layer marches through 3D noise. Instead of one hard surface, it adds many soft samples together. Threshold controls where cloud material appears. Step count controls smoothness. Density controls how fast the cloud becomes opaque.
The tradeoff is direct: more samples usually look smoother, but every sample runs for every pixel. Test heavy edits against the GPU performance test before assuming they are safe.
3D Fractal: math as geometry
3D Fractal uses an iterative field. The shader marches through space until the field behaves like a hit, estimates a normal, and applies lighting. The result feels more solid than fog or clouds because the volume function is being used as a procedural surface.
This preset is the strongest art showcase, but also the easiest to overload. Reduce ray steps first when tuning performance. Then reduce fractal iterations if the frame time is still unstable.
Learning path
Start with Fog Sphere, then Twirl Smoke, then Cloud Layer, then 3D Fractal. That order moves from the cleanest mental model to the most advanced. Keep the leaderboard nearby when you want hardware context for heavier experiments.
