Complementary has been the default recommendation for "what shaders should I install" for several years, and in 1.21.4 it is still the correct answer for most players. It is the most-downloaded shader pack on Modrinth with over 20 million downloads across both variants.
This is a complete review: what Complementary does, how Reimagined and Unbound differ, where it struggles, and who it is and isn't for.
What Complementary is
Complementary is a GLSL shader pack for Minecraft Java Edition, originally derived from BSL Shaders (with permission) and progressively rebuilt by EminGT. It runs on both Iris (Fabric) and OptiFine (though Iris is strongly recommended in 2026 for performance and compatibility reasons).
The philosophy is explicitly "vanilla-adjacent fidelity" — Complementary is not trying to be a photorealism mod or a full visual overhaul. It is trying to make vanilla Minecraft look like a much better version of itself, with correct lighting, soft shadows, water reflections, and dynamic clouds, without changing the artistic direction.
This positioning is why it's the right recommendation for most players. Players who want photorealism should look at BSL or Kappa PT. Players who want a different game entirely should look at Ray Tracing packs. Everyone else benefits from Complementary's balance.
Two variants — which one?
In 2023, EminGT split Complementary into two separate packs:
Complementary Reimagined
The artistic variant. Reimagined adds features beyond lighting correction: custom sky rendering, fog, cloud generation, custom nether and end effects, PBR support for resource packs, and per-biome effects. It has more visual customization options in the in-game shader menu.
Reimagined is heavier than Unbound. On a GTX 1660, expect 50–80 FPS at high settings, 80–110 at medium. On an RTX 4070, 120+ at high, 200+ at medium.
Best for: players who want the best possible visuals on mid-to-high hardware, content creators, screenshots.
Complementary Unbound
The performance variant. Unbound strips out the heavier artistic features and focuses on clean lighting, stable shadows, and water effects. The performance per visual quality ratio is better than Reimagined.
Unbound is better for:
- Mid-range hardware (GTX 1060, RX 580 era)
- Servers where stable framerates matter more than image quality
- Technical players who don't need custom sky
- Anyone who found Reimagined too resource-intensive
At equal settings, Unbound typically runs 20–40% faster than Reimagined on the same hardware.
If you're not sure which to use: start with Reimagined. If your FPS drops below your target (60 for most; 144 for high refresh displays), switch to Unbound or reduce Reimagined's shadow resolution first.
Installation — Iris only
In 2026, install Complementary through Iris, not OptiFine.
- Install Iris (requires Sodium)
- Download Complementary Reimagined or Unbound from modrinth.com — do not use unofficial mirrors
- In Minecraft: Options → Video Settings → Shader Packs → Open Shader Pack Folder
- Drop the
.zipfile into the folder - Select it in the list and click Apply
No profile restart needed. Iris loads shaders live.
Complementary supports 1.21.4 on Iris 1.8.x. If you see errors about unsupported GL features, update your GPU drivers — shader packs require OpenGL 4.0+ features.
Performance benchmarks (1.21.4)
These are directional numbers from community testing and the Modrinth discussion page. Test on your own hardware for authoritative results.
| Hardware | Vanilla (no shaders) | Complementary Unbound (High) | Complementary Reimagined (High) |
|---|---|---|---|
| GTX 1060 / Ryzen 5 2600 | 120–180 FPS | 50–70 FPS | 35–50 FPS |
| GTX 1660 / i5-10400 | 180–250 FPS | 80–110 FPS | 55–80 FPS |
| RTX 3070 / Ryzen 7 5800X | 300+ FPS | 150–200 FPS | 100–140 FPS |
| RTX 4070 / i7-13700K | 400+ FPS | 220–280 FPS | 150–200 FPS |
Shadow resolution is the biggest single performance lever. Dropping from 4096 to 2048 shadow res typically recovers 30–50% FPS with minimal visible quality loss unless you're doing close-up screenshots.
What it does well
Lighting. The most consistently praised feature. The way light falls through leaves, the soft transition from day into evening, the warm glow from torches and lanterns — all noticeably better than vanilla at a performance cost that's acceptable on modern hardware.
Water. Water reflections and underwater caustics are among the best in the mid-weight shader category. Complementary's water shader handles the transition between shallow and deep visually well.
Compatibility. Complementary works with virtually every major mod, including Create (the machine animations look excellent), Biomes O' Plenty, Oh The Biomes You'll Go, and most shader-compatible resource packs. The PBR support in Reimagined works with PBR texture packs like Faithful PBR.
Custom configuration. The in-game shader menu (accessible from Video Settings → Shader Packs → Shader Options) has more knobs than almost any other shader pack. You can tune shadow distance, disable specific effects, adjust the color grading, and change the sky style independently. This is genuinely useful for performance tuning.
What it doesn't do well
Nether. The nether visuals in Complementary are decent but not the pack's strength. The lava ocean shimmer is flat compared to some alternatives. Players who spend heavy time in the nether might prefer Sildur's Vibrant or BSL for that dimension.
Hardcore minimalism. If you want zero performance overhead from shaders — just better lighting, nothing else — Complementary is still somewhat heavy. In that case, look at AmbientOcclusion-only solutions or Iris's own shader presets.
Ray tracing. Complementary does not do path-traced global illumination. It uses rasterization-based shadow maps and reflection probes. If you specifically want GI, you're looking at packs like Kappa PT or Seus PTGI on capable hardware.
Settings recommendations
For a mid-range PC (GTX 1660 tier):
- Shadow resolution: 2048 (default is 4096 — this alone recovers 30%+ FPS)
- Shadow distance: 160 blocks (not max)
- Bloom: Off (aesthetic only, not free)
- Ambient Occlusion: On (low cost, high visual impact)
- Water effects: On
- Cloud style: Fast (vs Fancy)
For a high-end PC (RTX 3070+), run defaults and tune shadow res up to 4096 or 8192 if your FPS budget allows.
Compared to alternatives
| Shader | Weight | Style | Best for |
|---|---|---|---|
| Complementary Unbound | Light-medium | Vanilla-faithful | Mid-range daily play |
| Complementary Reimagined | Medium | Vanilla-faithful, artistic | High-end or screenshots |
| BSL Shaders | Medium | Warm, saturated | Players who want vivid colors |
| Sildur's Vibrant | Light | Minimal overhead | Low-end hardware |
| Kappa PT | Heavy | Path-traced realism | RTX 3080+ enthusiasts |
| Seus PTGI | Very heavy | Path-traced | RTX 3090+ only |
The short version: if BSL looks too orange/yellow to you, use Complementary. If Complementary's water looks too stylized, use BSL. Both are correct answers depending on taste.
Verdict
Complementary Reimagined and Unbound are the easiest recommendations in the shader space because they hit the widest target: good visuals, acceptable performance, strong compatibility, and active maintenance on 1.21.4.
Use Reimagined if your hardware is up to it and you care about how screenshots look. Use Unbound if you prioritize framerate or have mid-range hardware. Either way, install through Iris, start with shadow resolution at 2048, and tune from there.
Download links:
- Complementary Reimagined: https://modrinth.com/shader/complementary-reimagined
- Complementary Unbound: https://modrinth.com/shader/complementary-unbound
- Iris (required): https://modrinth.com/mod/iris
- BSL Shaders (alternative): https://modrinth.com/shader/bsl-shaders
