Describe the bug

With Floodfill turned off, custom blocks that are not a full block model render correctly and as expected.

However, when turned on and under artificial light (not sunlight), these blocks begin to almost completely darken up inward, leading to some rather annoying visuals.

Some vanilla models appear to be unaffected by this phenomenon, as are these two pots:

Some others, however, are subject to it. Redstone dust, for example:

Although it is mainly noticeable with blocks from other mods.

This only happens with artificial lighting, however, as the blocks are unaffected under sunlight.


It is not a matter of lighting either, as even if the blocks get a light source next to them the problem persists. Only handheld lights manage to get rid of it.

Describe how your minecraft is set up

• What GPU vendor you are using: Nvidia
• What operating system you are using: Windows 11
• What minecraft version you are playing: 1.21
• If you are using a special client for minecraft: No
• What shader loading mod you are using: Iris
• What version of the shader you are using: Bliss Shader Main
• If you are using any, what additional mods you are using besides the ones required to use the shader:
  • Distant Horizons
  • MrCrayfish's Furniture Mod: Refurbished
  • Valhelsia Furniture
  • Blockus
  • Chipped
  • Macaw's Holidays
  • Macaw's Doors
  • Light Emitting Diode

Describe how to reproduce the bug

Turn Floodfill on with everything else in default. Place any block that isn't a full-block model in a space without sunlight and with another placed light source.

Related: #235 #228 #201 #170

Would love to see this getting resolved, as these shaders along with Floodlight are such eye candy :)

(this spotlight effect comes from usage of a lvl 0 Light block from vanilla, discovered this accidentally but in retrospective it seems relevant to this issue now lol)

To give a little bit of context; for the whole floodfill effect to work, it needs to know what blocks are where, relative to the world.
the shader loader mod (iris/optifine) does not give this information at all, so the shader has to find that data all it by itself. I'm sure you don't want to hear a lengthy explanation of 3d voxel space meticulously checking for something or nothing within the world, so i will just cut to the end

The shader has to manually list what blocks are light sources, and if a block should not block light.
by default everything except air, is automatically a light blocking thing. Otherwise, the shader would need to manually list all things that should block light. that list is... significantly larger, so that's never gonna happen.

to stop specific blocks from blocking light, you need to manually add those blocks to the list of blocks that should not block light

• inside the shader, there is a block.properties file. the path is bliss-shader-main/shaders/block.properties
• look for a list labeled as block.50
• add the block IDs of the blocks you want to let light pass through to that list.
  note: there CANNOT be duplicate listings of a single ID, so make sure the ID you list is nowhere else in the entire file.

One other thing, the "voxel space" or 3D grid of the world is atleast 1x1x1 meter/1 block in volume for each grid unit. model shape does not exist in that voxel space. only the voxel shape exists. and that shape is 1 block large. So things that block light, but have had their model changed to be less than 1 block large, will still block light as if its 1 block large, regardless of what the model is.

yes, all of those are the same issue. some of them have been cleared away simply by putting block ID's in the groups that best fit them, like i explained above

Related: #235 #228 #201 #170

and #291