The Radiance Update

The worlds of RTC2 have always been strange, beautiful, and somewhat dangerous.

Now, we have finally given them the shine they deserve. 

This update introduces RTC RADIANCE: a shaderpack built specifically for RTC2. This (and all shaderpacks installed) will now understand the planets, atmosphere, and feelings throughout RTC2. 

RTC RADIANCE 5.3 is bundled directly inside of the mod, no separate shaderpack download is required. When Iris is installed, RTC2 installs and updates the bundled pack for you. A styled login notice appears when Iris is detected and tells you where to find the pack. If Iris is not installed, RTC2 will not advertise RADIANCE to you. 

RTC RADIANCE now follows RTC2's real celestial system instead of assuming every dimension uses Minecraft's ordinary day. 

PLANETS:

• Sunlight, moonlight, shadows, and shader lighting follow RTC2's world-seeded celestial phase. 
• Every planet respects its own solar-cycle length. 
• Vulcan's colossal day moves with its intended near-imperceptible slowness. 
• Faster worlds like Azura remain correctly synchronized. 
• The Moon and other long-cycle dimensions retain their authored timing. 
• Celestial lighting remains synchronized even when game-speed is accelerated. 

ATMOSPHERE, SHADOWS, AMBIENT LIGHTING:

• Shader shadows now point toward the same sun the player can actually see. 
• Warm daylight, cool moonlight,and restrained block-light bounce give the world depth without crushing RTC2's colored lighting. 
• Luminous items held in either hand cast light into the nearby world. 
• Shadows are smoother and more stable, without any noisey edges. 
• Bright sources receive a restrained bloom. 
• Camera-angle lens ghosts and aperture rings add a slight optical flare around brilliant celestial light without replacing RTC2's own sun and moon artwork. 
• RADIANCE was built around a simple rule: enhance the world without replacing its sky. 
• RTC2's custom skyboxes remain intact. 
• Vanilla sky colors, stars, sun and moon textures, clouds, and weather geometry are mostly preserved. 

Water is no longer the visual template for every liquid in RTC2. Each important fluid now somewhat behaves like the substance its supposed to represent. 

Water:

• Layered waves, surface gleam, and reflective highlights
• Stronger depth-based tint and opacity
• More convincing transmission through surfaces.

Liquid Mercury:

• Metallic screen-space reflections of visible terrain, sky, clouds, and shadows (although not perfect, the illusion is half-complete).

Crude Oil:

• Dark, viscous body color.
• Rainbow thin-film interference inspired by real a oil slick.

Other RTC Fluids:

• Cryogenic ammonia, conductive brine, dense acids, and the remaining RTC2 liquids receive material specific tinty, density, reflectivity, and motion. 
• Liquid surfaces and transmission receive the same distance fog as terrain. 

Weather:

• Rain and snow are a bit more clear, nothing too crazy though.
• Azura's cyan rain receives slight highlight
• Upwards facing blocks darken slightly when wet.

PARTICLES:

RTC2 lives on particle effects (like many other mods), so RADIANCE now treats them as first-class rendering rather than transparent debris.

• Opaque particles remain opaque.
• Authored translucent edges and lifetime fades remain smooth. 
• Bright sparks, fire, energy, and chemistry effects receive a restrained bloom.
• Ordinary transparent particles preserve the lighting, normals, and material information already rendered behind them. 

L.A.S.E.R.S:

• RTC2's lasers now cast colored light spill onto the surrounding environment.
• Laser pointers, laser diodes, autocarbine sights, and other bridges laser systems use their real beam position and color.
• The glow follows the beam in world space.

IRIS COMPATIBILITY (the focus of this update):

RTC2's world effects now have a deciated deferred rendering path for Iris.

This means railgun distortions, laser effects, mini-nukes, dangerous-material warping, radiation fields, oxygen meta-balls, auroras, lightning, weapon effects, and other late world-space visuals can survive the shader pipeline without fighting one another.

• Effects retain correct depth and no longer expose hidden objects through solid walls.
• Effects are kept out of inappropriate shadow and reflection passes. 
• Captured geometry is replayed with the correct camera matrices after Iris has completed te part of the frame that previously erased it.
• Vanilla rendering remains the fallback whenever no shader pack is active.

MODELS, ITEMS, AND TRANSPARENCY:

• Opaque model pixels remain fully opaque.
• Authored glass and truly translucent model sections still blend normally.
• Custom block models and held item models occlude the world ordinarily.

PERFORMANCE:

I'll be honest and say that I do not know how performance heavy RADIANCE is currently, I have also not tested it on AMD hardware but we have included a few shader presets like PERFORMANCE.

This pack is supposed to be deliberately lightweight in structure, preserving Minecraft's existing sky and weather rendering, and avoiding the experimental second-camera reflections seen in other packs. 

HOW TO ENABLE RTC RADIANCE:

1. Install Iris for the supported Minecraft 1.21.1 neoforge version, the tested version was 

iris-neoforge-1.8.12+mc1.21.1.jar

with

sodium-neoforge-0.6.13+mc1.21.1.jar

as dependency.

2. Launch RTC once.

3. Open Video Settings -> Shader Packs.

4. Select RTC RADIANCE (Bundled).

5. Begin with BALANCED Profile.

Final word...

This update is more than bloom or shadows. It is the point where RTC2's visual effects, planetary systems, fluids, weather, and shader pipeline finally behave as one world. We are so excited to bring full shader compatibility with RTC RADIANCE!!!