Disconnect mesh components in an .obj file based on a a number of "depth range" buckets

obj_mesh_depth_bucket_disconnect.py

import numpy as np
import trimesh

def load_mesh(file_path):
    return trimesh.load(file_path)

def compute_depth_ranges(mesh, num_buckets=5):
    # Extract vertex depths (assuming z-coordinate represents depth)
    depths = mesh.vertices[:, 2]
    
    # Compute depth range and bucket size
    depth_min, depth_max = np.min(depths), np.max(depths)
    bucket_size = (depth_max - depth_min) / num_buckets
    
    # Assign vertices to buckets
    bucket_assignments = np.floor((depths - depth_min) / bucket_size).astype(int)
    return bucket_assignments

def disconnect_mesh_components(mesh, bucket_assignments):
    # Create a new mesh for each bucket
    disconnected_meshes = []
    
    for bucket in range(np.max(bucket_assignments) + 1):
        # Get vertices and faces for this bucket
        vertex_mask = bucket_assignments == bucket
        vertices = mesh.vertices[vertex_mask]
        
        # Remap face indices to new vertex indices
        old_to_new = np.cumsum(vertex_mask) - 1
        faces = old_to_new[mesh.faces]
        
        # Only keep faces where all vertices are in this bucket
        valid_faces = np.all(vertex_mask[mesh.faces], axis=1)
        faces = faces[valid_faces]
        
        # Create a new mesh for this bucket
        bucket_mesh = trimesh.Trimesh(vertices=vertices, faces=faces)
        disconnected_meshes.append(bucket_mesh)
    
    return disconnected_meshes

def main(mesh_file_path, num_buckets=5):
    # Load the mesh
    mesh = load_mesh(mesh_file_path)
    
    # Compute depth ranges and assign buckets
    bucket_assignments = compute_depth_ranges(mesh, num_buckets)
    
    # Disconnect mesh components
    disconnected_meshes = disconnect_mesh_components(mesh, bucket_assignments)
    
    # Save or visualize the results
    for i, m in enumerate(disconnected_meshes):
        m.export(f"disconnected_mesh_{i}.obj")

if __name__ == "__main__":
    mesh_file_path = "download_model_1728232394.obj"
    main(mesh_file_path)