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The Lighting and Shadows page
By Ryleigh Newman · Published
The Lighting and Shadows page in Rockstar Shaders has 11 settings: the two ray-traced switches, the shadow maps and their resolution, entity shadows, the player's own shadow and reflection, dynamic lights, ambient occlusion and contact shadows. Five are restart-only and say so in their tip, three apply at once, and three apply when you leave the page with Done.
I am Ryleigh Newman and I made Rockstar Shaders because the light I wanted in Minecraft only existed in packs made for Windows, and I play on a Mac. This page says what each setting does and which ones, on my measurements, are not worth turning off.
Download free (1.0.0) Modrinth (pending)Minecraft 26.3, Fabric, macOS on Apple silicon. Install guide. Releases and bug reports on GitHub.
How a frame is lit
The pack draws terrain into a G-buffer and shades it in a deferred, physically based lighting pass. Sun shadows come from two systems together. The first is four cascaded shadow maps packed into one 2 by 2 atlas, 4096 or 2048 on a side, fitted with bounding spheres and texel snapping so edges do not crawl, with colored translucent casters, so stained glass tints the sunlight through it. The second is the Metal side-car, which traces the sun through the game's own chunk vertex buffers for exact shadows, sky visibility, one bounce of global illumination and the fog's sky occlusion; leaves are alpha-tested during the trace against the exported block atlas. Screen-space ambient occlusion and contact shadows fill the near field. At my window size, 1706 by 1966, the terrain G-buffer took 3.9 ms of a sunset frame on the M4 Max, the lighting pass 1.4, and the Metal shadow and sky traces 3.8 ms.
The ray-traced switches
Ray-traced shadows traces the sun through the Metal side-car for exact shadows and the fog's sky occlusion. Ray-traced fog traces sky and sun visibility for each cell of the volumetric fog, which is what keeps a cave or a hall from looking veiled. Both are on by default and restart-only. The tracing is Metal, not Vulkan: MoltenVK exposes no VK_KHR_ray_query, so the mod hands the rays to a native Metal side-car through VK_EXT_metal_objects, which is why it needs Apple Silicon.
Turning them off does not save time. In the sunset-bay pose on the M4 Max, everything on was 27.9 ms a frame; ray-traced shadows off, 29.7; ray-traced reflections off, 29.3; ray-traced fog off, 29.3; all three off, 29.5. Every fallback costs more than the trace it replaces, so touch these switches for a bug report, not for frame rate. Whether the tracer is running is the front page's Ray tracing: row and in the log as "Ray tracing: ready" or "Ray tracing unavailable:" with a reason (Troubleshooting).
Shadow maps, resolution and entities
Shadow maps is the rasterized cascade system, on by default and restart-only; with it off the ray trace stands in. Shadow resolution is the edge of the shadow atlas, 4096 by default or 2048, restart-only. 2048 is a quarter of the memory and fill, and on the noon test shot the cascades cost 0.39 ms at 2048 against 0.50 at 4096, a tenth of a millisecond. Entity shadows puts mobs, players and items into the shadow atlas, on by default and restart-only. Entities are captured as vanilla draws them and replayed into the atlas, and by default into the G-buffer too, so they take the pack's lighting; that switch, Entities lit by pack, is on Performance and Overlays. Far mountains beyond the cascades get their shadows from the extended horizon's own height map (View Distance).
Your own body
Two immediate toggles concern the first-person player. Player shadow is meant to make your own body cast a shadow in first person, and Player in reflections puts your body into the ray-traced water reflection. Both are on by default. I have to be plain about their status in 1.0. The player shadow is wired through vanilla's own feature pipeline into the shadow atlas, but no first-person shadow appears in my record. The player reflection is built and self-tested but not yet shown in a capture. The switches are there so the features land the moment the rest does; do not expect either yet.
Dynamic lights and colored block light
Dynamic lights is on by default and applies at once. A held torch, a dropped lantern or a burning mob lights its surroundings. Every frame the mod walks the entities within 48 m, takes an item's light level from its block, colors it by its emitter family, and feeds the nearest eight lights to the shaders. They cast no shadows. Block light from placed emitters is separate and has no switch: a camera-centerd volume of emitter radiance lets glowstone and lanterns light the air and the fog in their own color, which is how colored light reaches the fog on Fog and Volumetrics. Its known limit, which I accept at this stage, is that light leaks through thin walls.
The near field: AO, contact shadows, parallax
AO steps is the number of GTAO samples per direction, 8 by default, from 2 to 12; more is smoother in crevices. Contact shadow steps is the march length of the screen-space contact shadow, 16 by default, from 4 to 24 in steps of 2. Parallax mapping gives blocks relief from their own texture and ships off. These three are tune settings and apply on Done. I have no per-setting timing for them; Show pass timings prints every pass in GPU milliseconds for your own scene.
Every setting on the page
| Setting | Default | Applies |
|---|---|---|
| Ray-traced shadows | On | Restart |
| Ray-traced fog | On | Restart |
| Shadow maps | On | Restart |
| Shadow resolution | 4096 (or 2048) | Restart |
| Entity shadows | On | Restart |
| Player shadow | On | At once |
| Player in reflections | On | At once |
| Dynamic lights | On | At once |
| AO steps | 8, from 2 to 12 | Done |
| Contact shadow steps | 16, from 4 to 24, step 2 | Done |
| Parallax mapping | Off | Done |
A restart-only change is written to the config, and the front page header reads "A restart-only setting changed: it applies at the next launch." until you relaunch. Those five keep their value through Reset to defaults, which only forgets tune overrides; the config file itself is described on Advanced.
Download free (1.0.0) Modrinth (pending)Minecraft 26.3, Fabric, macOS on Apple silicon. Install guide. Releases and bug reports on GitHub.
Related
Questions
Are the shadows really ray traced?
Yes, through Metal. MoltenVK exposes no Vulkan ray query on a Mac, so the mod hands the sun rays to a native Metal side-car that traces against the game's own chunk geometry. The cascaded shadow maps cover what the tracer does not.
Will turning ray tracing off give me more frames?
No. In the same scene on the M4 Max, everything on was 27.9 ms a frame and ray-traced shadows off was 29.7. Every fallback costs more than the trace it replaces.
Why does my own body not cast a shadow?
It is a known limit of this release. The Player shadow switch is wired, but no first-person shadow appears yet.
Does a torch in my hand cast shadows?
It lights its surroundings, as one of the eight nearest dynamic lights within 48 m, but dynamic lights cast no shadows.
Light is coming through a thin wall. Is that a bug?
It is a known and accepted limit at this stage: the colored block-light volume leaks through thin walls.
Which of these settings need a restart?
Ray-traced shadows, Ray-traced fog, Shadow maps, Shadow resolution and Entity shadows. Their tips end with Restart to apply, and the front page header says a restart is pending.