Dev Log – Milestone: Ptolemaic Illumination System Online

Retroactive: May 4–15, 2025

Simulating planetary life begins with simulating planetary light.

In early May, the PtolemaicIlluminationSystem came online—marking the moment when Colonies: Genesis of E.D.E.N. gained its first working model of solar irradiance. Named for its role in tracking celestial motion, this system forms the foundation for all climate and ecosystem behavior to follow.

This system serves as a placeholder model, designed to simulate sunlight patterns based on planetary rotation and axial tilt—without yet requiring full orbital mechanics. It allows surface irradiance to vary over time and latitude, creating functional day/night cycles and seasonal drift. Later, it will be replaced or extended by a full orbital simulation that accounts for elliptical orbits, axial precession, and variable solar distances.

Key features brought online:

• Planetary rotation and axial tilt modeled in a simplified solar position system
• Simulation time mapped to solar vector and angle of incidence
• Per-tile irradiance values computed and applied to surface heating
• Temporal changes (diurnal and seasonal) visible in tile temperature data

The illumination system doesn’t just light up the world—it powers energy flow across the biosphere. With it, tiles warm under sunlight, drive evaporation, influence air currents, and shape everything from vegetation to migration.

As of this milestone, the system was fully driving surface heating and laying the groundwork for the now-operational weather engine. Integration with Unity’s directional light (“Sun” tag) began shortly after to align visual and simulation light sources.

This is where the planet begins to turn—and soon, where its orbit will shape its fate.