36 lines
1.2 KiB
Python
36 lines
1.2 KiB
Python
import numpy as np
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from stl import mesh
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def simplify_stl_grid(input_path, output_path, target_ratio=0.1):
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m = mesh.Mesh.from_file(input_path)
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vertices = m.vectors.reshape(-1, 3)
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min_v = vertices.min(axis=0)
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max_v = vertices.max(axis=0)
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bbox_size = max_v - min_v
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max_dim = np.max(bbox_size)
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# Adjust resolution to rough target_ratio by guessing.
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# The number of vertices drops roughly by (resolution_factor)^2.
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# So if we want 10% faces, resolution_factor can be heuristically set.
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# Let's try 0.05
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grid_size = max_dim * 0.05
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v_idx = np.round((vertices - min_v) / grid_size).astype(np.int32)
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_, unique_idx, inv_idx = np.unique(v_idx, axis=0, return_index=True, return_inverse=True)
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new_vertices = vertices[unique_idx]
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faces = inv_idx.reshape(-1, 3)
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valid = (faces[:,0] != faces[:,1]) & (faces[:,1] != faces[:,2]) & (faces[:,0] != faces[:,2])
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valid_faces = faces[valid]
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new_m = mesh.Mesh(np.zeros(valid_faces.shape[0], dtype=mesh.Mesh.dtype))
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for i, f in enumerate(valid_faces):
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for j in range(3):
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new_m.vectors[i][j] = new_vertices[f[j]]
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new_m.update_normals()
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new_m.save(output_path)
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