import trimesh
import xatlas

# We use trimesh (https://github.com/mikedh/trimesh) to load a mesh but you can use any library.
mesh = trimesh.load_mesh("input.obj")

# The parametrization potentially duplicates vertices.
# `vmapping` contains the original vertex index for each new vertex (shape N, type uint32).
# `indices` contains the vertex indices of the new triangles (shape Fx3, type uint32)
# `uvs` contains texture coordinates of the new vertices (shape Nx2, type float32)
vmapping, indices, uvs = xatlas.parametrize(mesh.vertices, mesh.faces)

# Trimesh needs a material to export uv coordinates and always creates a *.mtl file.
# Alternatively, we can use the `export` helper function to export the mesh as obj.
xatlas.export("output.obj", mesh.vertices[vmapping], indices, uvs)

# Both `xatlas.parametrize` and `xatlas.export` also accept vertex normals

mesh1 = trimesh.load_mesh("input1.obj")
mesh2 = trimesh.load_mesh("input2.obj")

atlas = xatlas.Atlas()

atlas.add_mesh(mesh1.vertices, mesh1.faces)
atlas.add_mesh(mesh2.vertices, mesh2.faces)

# Optionally parametrize the generation with
# `xatlas.ChartOptions` and `xatlas.PackOptions`.
atlas.generate()

vmapping1, indices1, uvs1 = atlas[0]
vmapping2, indices2, uvs2 = atlas[1]

vertices1, indices1, uvs1 = load_mesh_with_uvs("input1.obj")
vertices2, indices2, uvs2 = load_mesh_with_uvs("input2.obj")

atlas = xatlas.Atlas()

atlas.add_uv_mesh(uvs1, indices1)
atlas.add_uv_mesh(uvs2, indices2)

atlas.generate()

vmapping1, indices1, uvs1 = atlas[0]
vmapping2, indices2, uvs2 = atlas[1]

atlas.mesh_count  # Number of meshes
len(atlas)        # Convenience binding for `atlas.mesh_count`
atlas.get_mesh(i) # Data for the i-th mesh
atlas[i]          # Convenience binding for `atlas.get_mesh`

atlas.width       # Width of the atlas 
atlas.height      # Height of the atlas

atlas.utilization        # Utilization of the first atlas
atlas.get_utilization(i) # Utilization of i-th atlas

# The image requires passing custom PackOptions:
#   pack_options = xatlas.PackOptions()
#   pack_options.create_image = True
#   atlas.generate(pack_options=pack_options)
atlas.chart_image        # Debug image of the first atlas
atlas.get_chart_image(i) # Debug image of the i-th atlas

...               # See xatlas documentation for all properties