glb2mesh.py

#! /usr/bin/env python

""" Convert a GLB file to other mesh formats. """

import sys
import os
import pymeshlab as ml
import trimesh
import glbutils


def glb2mesh(inname, outname, removeColor=False, meshColor=None):
    """Convert a GLB file to other mesh formats.

    If the output format is supported by Trimesh, the GLB us loaded with
    Trimesh and written out with Trimesh.  Formats supported by Trimesh
    include STL, PLY, OBJ, OFF, GLB, and GLTF.

    For output formats not supported by Trimesh, particularly X3D and VRML 2.0,
    we use Trimesh to create an intermediate PLY file.  This PLY file is then
    passed to MeshLab to produce the final output file.

    Note that in creating this PLY file, any scene hierarchy and non-mesh
    data such as camera, lights or animation are discarded.  All mesh
    objects in the scene graph are merged into one bundle of triangles.
    """

    try:
        tmesh = trimesh.load(inname)
    except ValueError:
        print("Error: failed to load ", inname)
        sys.exit(1)

    print("Trimesh load:", inname)

    words = outname.split(".")
    suffix = words[-1]

    # tmesh could be a Scene, a Trimesh, or other types
    #
    mesh = glbutils.getSceneMesh(tmesh)

    if mesh is None:
        print("Warning: no mesh found")
        return

    if removeColor:
        print("Removing vertex color")
        glbutils.removeVertexColor(mesh)

    if meshColor is not None:
        print("Setting face color:", meshColor)
        glbutils.setFaceColor(mesh, meshColor)

    if suffix in trimesh.exchange.load.mesh_formats():
        # Use trimesh to write the output mesh
        #
        try:
            mesh.export(outname)
        except ValueError:
            print("Error: failed to export", inname, "to", outname)
            sys.exit(2)
        print("Trimesh export:", outname)

    else:
        # write out a PLY and then use MeshLab
        dotpos = inname.rfind(".")
        if dotpos != -1:
            rootname = inname[0:dotpos]
        else:
            rootname = inname
        tmpname = rootname + ".ply"

        mesh.export(tmpname)
        try:
            ms = ml.MeshSet()
            ms.load_new_mesh(tmpname)
            print("Meshlab load: ", tmpname)
        except ValueError:
            print("Error: Intermediate conversion failed.")
            sys.exit(3)

        try:
            ms.save_current_mesh(outname)
            print("Meshlab save: ", outname)
        except ValueError:
            print("Error: failed to save", outname)
            sys.exit(4)

        if tmpname != inname:
            os.remove(tmpname)


if __name__ == "__main__":

    in_file = "teapot.glb"
    out_file = "teapot.x3d"

    if len(sys.argv) > 1:
        in_file = sys.argv[1]
        if len(sys.argv) > 2:
            out_file = sys.argv[2]
        else:
            out_file = in_file.replace(".glb", ".x3d")

    print("Converting", in_file, "to", out_file)
    glb2mesh(in_file, out_file)