Fix faint lightshafts when Voxy/Distant Horizons is enabled

[aLink536]

What's the issue

When Voxy or Distant Horizons is enabled, lightshafts appear very faint — sometimes nearly invisible depending on how large the LOD render distance is set.

Root cause

In volumetricLight.glsl, the Voxy/DH branch sets maxDistance = renderDistance * 0.5 for all pixels. The weight accumulation normalises against maxDistance:

float sliceWeight = smoothstep1(pow(nextDistance / maxDistance, fogCurve))
                  - smoothstep1(pow(lastDistance / maxDistance, fogCurve));

With a large LOD render distance (e.g. 512 chunks → maxDistance = 4096), a ray that stops at vanilla geometry (~192 blocks) only accumulates ~4% of the expected weight. The effect scales badly — the larger the Voxy render distance the user has set, the fainter the shafts.

Fix

Decouple the weight-normalisation distance from the LOD extension distance:

• Non-sky pixels keep maxDistance = far * 0.98 — weight normalisation is identical to non-Voxy behaviour, so lightshafts are full brightness regardless of LOD render distance setting.
• Sky pixels (both vanilla and LOD depth are 1.0) use loddedMaxDistance = max(renderDistance * 0.5, far * 0.98) — the ray still extends into the LOD zone and weights correctly integrate to 1.0.

Files changed

• shaders/lib/atmospherics/volumetricLight/volumetricLight.glsl

[aLink536]

On Extreme

Before:

After:

[EminGT]

Thank you for trying to help, but this is intentional. Extreme light shafts make lods invisible and most people don't like that.

[aLink536]

@EminGT May be worth tweaking this further, in some cases even on extreme the rays are not visible with Voxy enabled. I'd look at adding a more granular 'strength' setting so people can find the balance that works for them - benefits non voxy users as well.

Voxy enabled:

Voxy Disabled:

Voxy enabled with my fix - (ingame time changed is why light shafts have moved):

[EminGT]

Hm, the Extreme setting wasn't supposed to change with Voxy. That's an issue