Custom Blocks: Vanilla Voxel Shapes and Culling

Wait-free rendering in Minecraft relies heavily on face culling: skipping the drawing of block faces that are completely pressed against another solid block. In the Java edition, a unified concept called a VoxelShape controls collision, selection, and light occlusion all at once. In Bedrock Edition, these responsibilities are split across multiple components in the behavior pack and culling definitions in the resource pack.

When you assign the standard unit cube identifier to a custom block, the engine treats it as an opaque 16x16x16 volume. The moment you switch to a custom geometry file in the `minecraft:geometry` component, Bedrock assumes your block might have transparent gaps. Without further configuration, it stops culling the faces of adjacent full blocks to prevent players from seeing into the void, and it defaults the physical hitboxes back to a full cube unless told otherwise.

Physical movement and player cursor interaction are controlled by `minecraft:collision_box` and `minecraft:selection_box`. Both components measure their bounds in block pixels (1/16th of a block) using an `origin` array and a `size` array. The origin is always measured from the bottom-center of the block space, making a full block start at `[-8, 0, -8]` with a size of `[16, 16, 16]`.

Prior to format version 1.21.50, each component only accepted a single box. Modern format versions allow a `boxes` array inside `minecraft:collision_box`, letting you assemble compound voxel shapes like L-shaped stair steps or hollow cauldrons where entities can actually stand inside the model.

{
  "format_version": "1.21.50",
  "minecraft:block": {
    "description": {
      "identifier": "wiki:stone_step"
    },
    "components": {
      "minecraft:geometry": {
        "identifier": "geometry.wiki.stone_step",
        "culling": "wiki:culling.stone_step"
      },
      "minecraft:material_instances": {
        "*": {
          "texture": "stone",
          "render_method": "opaque"
        }
      },
      "minecraft:selection_box": {
        "origin": [-8, 0, -8],
        "size": [16, 16, 16]
      },
      "minecraft:collision_box": {
        "boxes": [
          {
            "origin": [-8, 0, -8],
            "size": [16, 8, 16]
          },
          {
            "origin": [-8, 8, 0],
            "size": [16, 8, 8]
          }
        ]
      }
    }
  }
}

If your custom block is a standard 16x16x16 solid block, you do not need to create a `.geo.json` model file or write custom culling rules. Bedrock includes a built-in geometry identifier specifically for this purpose: `minecraft:geometry.full_block`.

Using `minecraft:geometry.full_block` inside the `minecraft:geometry` component tells the engine to use the hardcoded vanilla cube shape. It automatically enables full neighbor face culling, proper ambient occlusion, and standard UV mapping across all six faces, matching the exact rendering performance of vanilla stone or dirt.

{
  "format_version": "1.20.80",
  "minecraft:block": {
    "description": {
      "identifier": "wiki:polished_granite_brick"
    },
    "components": {
      "minecraft:geometry": "minecraft:geometry.full_block",
      "minecraft:material_instances": {
        "*": {
          "texture": "wiki_polished_granite_brick",
          "render_method": "opaque"
        }
      }
    }
  }
}

When two custom blocks sit next to each other, or when a custom block sits against a vanilla block, the `culling` property inside `minecraft:geometry` controls which parts of your model disappear. The string you provide here matches a file inside the `RP/block_culling/` directory of your resource pack.

A block culling file maps individual bones or cubes from your geometry to a specific neighbor direction (`up`, `down`, `north`, `south`, `east`, `west`). By setting the `condition` to `same_culling_layer` or `same_block`, you can make glass-like blocks or connected slabs hide their interior seams when placed side by side, without causing x-ray glitches against full solid blocks.

{
  "format_version": "1.20.60",
  "minecraft:block_culling_rules": {
    "description": {
      "identifier": "wiki:culling.stone_step"
    },
    "rules": [
      {
        "direction": "down",
        "geometry_part": {
          "bone": "base_slab",
          "cube": 0,
          "face": "down"
        }
      },
      {
        "direction": "north",
        " condition": "same_block",
        "geometry_part": {
          "bone": "base_slab",
          "cube": 0,
          "face": "north"
        }
      }
    ]
  }
}

Visual shape and physical bounds do not automatically stop skylight or blocklight from passing through your block. A custom geometry block defaults to letting some or all light pass unless you pair it with `minecraft:light_dampening`.

This component takes an integer from `0` (completely clear to light, like air or glass) to `15` (completely opaque, blocking all light like stone). For partial shapes such as slabs or stairs, setting `minecraft:light_dampening` to `0` or a low value prevents dark, unnatural shadow patches from forming directly underneath the block when placed in sunlight.

Applies to Bedrock Edition 1.20.60+ for stable `minecraft:geometry`, `minecraft:collision_box`, `minecraft:selection_box`, and `RP/block_culling/`. Multiple collision boxes via the `boxes` array require format_version 1.21.50 or newer. No experimental toggles are required.

Read out of the game itself, so the ids match the version you are building for.