Nebula HDR screensaver

A deep-space nebula rendered in real-time volumetric raymarching on the GPU. The camera flies through translucent clouds of emissive gas, sculpted by a tiling 3D noise field with Worley erosion and lit by gradient relief, shell halos, and ionization-front rims.

The palette centres on deep violet and indigo, with magenta and cool-blue accents. Foreground masses occlude background stars with true depth. Dense star clusters glow as pointillistic distant galaxies, and the brightest stars throw subtle aperiodic HDR flares with four-point diffraction spikes.

A split-resolution pipeline keeps stars pin-sharp at native resolution while the gas runs at an adaptive lower resolution. Each screensaver activation randomises the camera path, nebula formation, and star field so no two sessions look alike.

Features:
- Volumetric raymarching through a 3D noise field
- HDR output with automatic SDR fallback
- Configurable render resolution, frame rate, and zoom speed
- Burn-in safe: every element moves or cross-fades, so no pixel holds a static image
- No network access, no ads, no tracking

Optimized for the NVIDIA Shield and HDR displays, but runs on any Android phone or TV with a sufficiently powerful GPU.

Deeper blacks on standard (non-HDR) displays:

• On SDR screens the faint floor now settles to true black instead of a slightly lifted grey, with a light contrast lift so gas masses separate more cleanly
• HDR output is unchanged