almeshmerge 0.1.36

High-performance OBJ merge and texture atlas pipeline

almeshmerge

High-performance OBJ merge and atlas generation library.

Build

chcp 65001 && uv build --wheel --out-dir dist

CI Release (GitHub Actions)

• Workflow: .github/workflows/release.yml
• Trigger:
  • Push tag: v* (recommended, for example v0.1.29)
  • Manual run: workflow_dispatch
• Build matrix:
  • OS: Linux (ubuntu-latest) and Windows (windows-latest)
  • Python: 3.11, 3.12, 3.13, 3.14 (wheel via cibuildwheel)
• Publish:
  • Uses PyPI Trusted Publisher (OIDC), no API token required in repository secrets.
  • A pre-publish guard checks that tag version matches pyproject.toml version.

Recommended release commands:

git tag v0.1.29
git push github v0.1.29

If a run fails due to transient CI issues, rerun the failed jobs from the GitHub Actions UI or use workflow_dispatch.

Python API

from almeshmerge import merge_obj_to_atlas

result = merge_obj_to_atlas(
    input_objs=["a.obj", "b.obj"],
    output_dir="out",
    split_o=True,
    split_g=True,
    atlas_max_size=8192,
    atlas_padding=4,
    atlas_pow2=True,
    atlas_allow_rotate_90=True,
    atlas_max_count=0,
    spatial_cluster_radius=-1.0,
    atlas_target_utilization=0.92,
    uv_repeat_exclude_merge=True,
    simplify_ratio=0.8,
    vertex_key_mode="pos",  # default: keep topology vertex count stable
)
print(result)

Parameters

• split_o: Whether to split by o objects.
• split_g: Whether to split by g groups.
• front_axis / up_axis: Input axis convention, defaults to Y-front and Z-up.
• right_handed: Use right-handed axis transform.
• atlas_max_size: Max atlas side length.
• atlas_padding: Padding pixels between packed textures.
  • Default is 4.
  • For Blender viewport preview, 8 or higher is often safer if you see tile-edge bleed.
  • In Blender, prefer Image Texture Extension=Extend or Clip for atlas materials.
• atlas_pow2: Force atlas width/height to powers of two.
• atlas_allow_rotate_90: Allow 90-degree placement rotation.
• atlas_max_count: Max number of generated atlases (0 means unlimited).
• spatial_cluster_radius: Spatial clustering radius for unit-wise texture packing (<=0 disables clustering).
• atlas_target_utilization: Target utilization threshold used to trigger extra packing refinement.
• uv_repeat_exclude_merge: Exclude UV-repeat units from merge and keep them as original textures.
• simplify_ratio: Mesh simplification ratio before export.
• vertex_key_mode: Export dedup key mode. pos is default and keeps topology vertex count stable while writing split v/vt/vn indices; pos_uv ignores normal in dedup; full keeps position+UV+normal in a unified index.

Diagnostics for Atlas Stability

merge_obj_to_atlas() now returns extra diagnostics that help locate parameter-sensitive texture issues:

• diagnostics.atlas_rot90_count / diagnostics.atlas_rot90_ratio
• diagnostics.uv_edge_01_hits / diagnostics.uv_near_edge_hits
• compose_diagnostics.crop_size_mismatch_count
• compose_diagnostics.crop_size_mismatches (first 20 samples)

Interpretation:

• crop_size_mismatch_count == 0 means C++ crop estimation and Python crop execution are consistent.
• uv_edge_01_hits == 0 means remapped UVs do not collapse to exact 0/1 boundaries.
• Large changes in atlas_rot90_ratio across parameter sets are expected and indicate different packing paths.

Regression Matrix (Recommended)

For Blender preview stability, run at least:

• atlas_padding: 4, 8
• atlas_max_size: 2048, 4096, 8192

Pass criteria:

• No visible large-scale texture scramble in Blender.
• compose_diagnostics.crop_size_mismatch_count == 0.
• diagnostics.uv_edge_01_hits == 0.