Decimate meshes with the Blender Python API

decimate.py

# Installation:
#
#     pip3 install bpy
#
# Usage:
#
#    python3 decimate.py /path/to/meshes/* --ratio 0.025
#

import bpy
import os
import argparse


MODIFIER_NAME = 'DecimateMod'


def main():
    parser = argparse.ArgumentParser(description='Decimate a mesh')

    parser.add_argument('input', type=str, nargs='+',
                        help='Path to the mesh file')
    parser.add_argument('--ratio', type=float, default=0.025,
                        help='Decimate ratio')
    parser.add_argument('--subdir', type=str, default='simplified',
                        help='Subdirectory to save the decimated meshes')
    parser.add_argument('--overwrite', action='store_true', default=False,
                        help='Overwrite existing meshes')
    args = parser.parse_args()

    for input in args.input:
        if not input.endswith('.stl'):
            print('File not supported, skipping', input)
            continue

        if not os.path.exists(input):
            print('File doesn\'t exist, skipping', input)
            continue

        # Set output path
        parent_dir = os.path.dirname(input)
        decimated_dir = os.path.join(parent_dir, args.subdir)
        if not os.path.exists(decimated_dir):
            os.makedirs(decimated_dir)
        output = os.path.join(decimated_dir, os.path.basename(input))
        if not args.overwrite and os.path.exists(output):
            print('Output already exists, skipping', input)
            continue

        print('Decimating', input)

        # Clear Blender scene
        for obj in bpy.data.objects:
            bpy.data.objects.remove(obj, do_unlink=True)
        for mesh in bpy.data.meshes:
            bpy.data.meshes.remove(mesh)

        # Import mesh
        bpy.ops.import_mesh.stl(filepath=input)

        # Decimate mesh
        modifier = bpy.context.object.modifiers.new(MODIFIER_NAME, 'DECIMATE')
        modifier.ratio = args.ratio
        bpy.ops.object.modifier_apply(modifier=MODIFIER_NAME)

        # Export mesh
        bpy.ops.export_mesh.stl(filepath=output)


if __name__ == '__main__':
    main()