Bedrock geometry

assets/<namespace>/ancientcreature/geo/<name>.geo.json

A standard Blockbench Bedrock Entity export. No conversion step.

Supported

• both file layouts Bedrock accepts: 1.12.0+ ("minecraft:geometry": [...]) and the legacy 1.8.0 / 1.10.0 layout ("geometry.name": {...}), including "geometry.child:geometry.parent" inheritance within a file
• several geometries per file. A client entity refers to them by identifier (geometry.triceratops); the first geometry in a file can also be referred to by file id (ancientcreature:triceratops), which is how format-1 species files did it
• description.identifier (must start with geometry.), texture_width, texture_height
• bones: name, parent, pivot, rotation, bind_pose_rotation, mirror, inflate, never_render (or neverRender), reset, locators, poly_mesh
• cubes: origin, size, inflate, mirror, pivot + rotation, box uv, per-face uv with uv_size and uv_rotation
• poly_mesh: explicit polygons, or "tri_list" / "quad_list"
• locators, as [x, y, z] or { "offset": [...], "rotation": [...] }. Animation sound and particle effects can play at them
• numbers written as strings, as Bedrock allows

Bone and locator names are matched case-insensitively, as in Bedrock.

Nothing is parsed per frame. Geometry is read and baked once per resource reload and cached; the cache is dropped wholesale on the next reload, so no stale model survives an F3+T.

Validation

Rejected at load, naming the file and every problem it found:

Problem	Example
Duplicate bone names	two bones called head
Unknown parent	"parent": "torso" with no torso bone
Parent cycle	a parents b, b parents a
Negative or non-finite cube size	"size": [-1, 1, 1]
Non-finite cube origin	NaN from a broken export
Malformed pivot	non-finite values
Bad identifier	"identifier": "my_model" — must start with geometry.
Non-positive texture size	"texture_width": 0

UV

Box UV, per-face UV and uv_rotation all go through one path and match Blockbench texel for texel. Box UV is expanded to per-face rectangles the way Bedrock does it: cube sizes floored to whole texels, and mirror flipping each face and swapping east and west.

Bedrock's east face is the cube's negative-X side and west the positive side. This is how Blockbench reads and writes them, so it only matters if you write geometry by hand.

Texture resolution

Textures are not restricted to 16×16. texture_width and texture_height may be any positive sizes that match the PNG; 32, 64, 128, 256 and 512 are all practical choices. Higher resolution gives room for gradients and mottling, but costs more memory. The shipped Pteranodon uses 128×128 and Deinonychus and Ankylosaurus use 256×256, while the much larger Brachiosaurus UV layout uses 512×512.

Rotated cubes

A cube with its own pivot and rotation is baked straight into its bone's vertices, rotated about its own pivot. The baked model has exactly one part per bone, so animations address bones by their real names.

Coordinate conversion

The baker uses the same mapping as Blockbench's Bedrock importer and Java exporter together, so a model renders in game exactly as it does in Blockbench and in Bedrock:

Quantity	Conversion
Bone offset	(px - parent.px, -(py - parent.py), pz - parent.pz), plus 24 on Y for root bones
Bone and cube rotation	The file's [x, y, z] degrees, as written
Cube box	(ox - px, py - oy - height, oz - pz) relative to the bone pivot

Animation keyframes are applied the way Blockbench's Java exporter applies them: rotation added as-is, position as (x, -y, z), scale multiplied.

Checked, not assumed

BedrockGeometryTest bakes a Bedrock cow and compares every vertex and UV against the vanilla Java cow, and checks per-face UV against box UV, uv_rotation, rotated cubes, legacy inheritance and poly meshes.

Packs from earlier releases

Format-1 species files were authored for the earlier axis handling. Their geometry and animations are converted on load so they look exactly as they did; LegacyAxesTest checks this against the old baker.

Not used

visible_bounds_width, visible_bounds_height and visible_bounds_offset are parsed but ignored — culling uses the entity's own bounding box, which comes from the species' physical block.