Clouds Stack

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Cloud Stack System Overview

Rombo Sky implements an advanced Cloud Stack system that allows for the procedural generation and customization of volumetric clouds. This modular architecture enables users to create diverse cloud formations through a standardized interface that integrates seamlessly with the renderer's volumetric ray marching system.

The Cloud Stack interface consists of three floating-point sockets that serve as the primary connection points:

  • Density Output: Returns the computed density value at the current sampling position
  • Shape Modulation: Provides shape modification factors for the cloud formation
  • Detail Modulation: Controls fine detail and noise patterns within the cloud structure

This interface allows cloud shaders to be attached to these sockets to modify or completely replace the default cloud generation system. The ray marching engine evaluates these shaders at each sampling point during volumetric rendering, creating a physically accurate representation of diverse cloud types. That allows for seamless integration of external cloud shaders through a standardized interface. Basically anything can be attached to a cloud slot, allowing for various shapes and cloud formations together with their density controls and animation parameters.

Integration Note: The Cloud Stack system works in conjunction with the main renderer's atmospheric scattering and lighting model. Cloud formations respond to sunlight, cast volumetric shadows (on the atmosphere and on themselves), and interact with atmospheric effects to create a cohesive sky environment.

Stratus Clouds

Stratus clouds are characterized by their layered, horizontal structure with broad coverage. These are typically low-altitude clouds that create even, sheet-like formations. The Stratus cloud generator produces realistic stratiform cloud layers with controllable coverage, density, and detail.

Structure Parameters

frequency
(Vector3: 1.0, 1.0, 1.0)
Controls the spatial frequency of cloud patterns in 3D space. Adjusting individual components stretches or compresses the cloud pattern along different axes.

Frequency component effects:

  • X component: Stretching along the east-west axis
  • Y component: Stretching along the vertical axis
  • Z component: Stretching along the north-south axis

Lower values create larger, broader patterns; higher values create more detailed, frequent variations.

coverage
(0.0-1.0)
Controls the overall cloud coverage percentage. Higher values create more extensive cloud cover with fewer gaps.
fill
(0.0-1.0)
Controls the density distribution within covered areas. Higher values create more uniform, solid-looking cloud layers.

Coverage vs. Fill:

  • Coverage determines where clouds appear
  • Fill determines how solid those clouds are
  • For broken stratus: high coverage (0.7-0.9) with low fill (0.1-0.3)
  • For overcast: high coverage (0.8-1.0) with high fill (0.5-0.8)

Detail and Appearance

fractal
(0.0-2.0, soft: 0.0-1.0)
Controls the amount of fractal detail in the cloud structure. Higher values create more complex, naturalistic edge detail.
swirlness
(-1.0-1.0)
Controls the amount of turbulent swirling in the cloud pattern. Positive values create clockwise swirls, negative values create counter-clockwise swirls.
contrast
(0.0-1.0)
Controls the density contrast between different areas of the cloud layer. Higher values create more defined transitions between dense and sparse regions.

Detail Control Recommendations:

  • Smooth, even stratus: low fractal (0.0-0.1), low swirlness (0.0), low contrast (0.0-0.1)
  • Natural stratus: moderate fractal (0.2-0.4), slight swirlness (0.1-0.2), moderate contrast (0.1-0.3)
  • Turbulent stratus: high fractal (0.4-0.8), higher swirlness (0.3-0.5), higher contrast (0.3-0.5)

Density Control

density
(0.0-10.0, soft: 0.0-5.0)
Controls the overall density multiplier for the cloud volume. Higher values create thicker, more opaque clouds.

Density interacts strongly with the main Rombo Sky renderer's cloud parameters:

  • For thin, transparent stratus: use lower density (0.2-0.5)
  • For typical stratus: use moderate density (0.5-1.5)
  • For thick, rain-bearing stratus: use higher density (1.5-3.0)
  • Extremely high values (3.0+) create unnaturally dense clouds

Animation Parameters

anim
(soft: 1.0-1000.0)
Controls the animation time position. Used as a seed value for evolving cloud patterns over time.
speed
(0.01+, soft: 0.01-1.0)
Controls the rate of cloud pattern evolution. Higher values create faster-moving cloud formations. By providing different Speed values for different Cloud layers one can achive parallax clouds animation.
animGlobal
(boolean)
When enabled, uses the global animation time from the main renderer. When disabled, uses the local anim parameter. Actually the full animation time computation is as simple as : local_anim x local_speed x global_anim x global_speed.

Animation recommendations:

  • For slow-moving stratus: use low speed (0.01-0.05)
  • For typical movement: use moderate speed (0.05-0.2)
  • For time-lapse effects: use higher speed (0.2-0.5)
  • For parallax effects use different Speed values
  • Enable animGlobal to synchronize with other animated elements in the scene

Best Practices: Stratus clouds tend to be most realistic at lower altitudes. When using the Stratus cloud generator, set appropriate cloudsHeight (1000-3000) and cloudsThickness (500-1500) in the main Rombo Sky renderer for optimal results.

Typical Use Cases:

  • Overcast Sky: High coverage and fill with moderate density
  • Morning Fog/Mist: Lower height setting with high coverage and low density
  • Light Cloud Cover: Moderate coverage with low fill and density
  • Weather Transition: Animate between different coverage/density settings

Cumulus Clouds

Documentation coming soon...

Swirl Clouds

Documentation coming soon...

 
 
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