Blender script to paint OBJ file vertices with material diffuse color and export as AeonEngine mesh.

VertexPaintMaterials.py

#!/bin/blender -b -P
import bpy
import mathutils
import glob

# This was created to work with Kenney's 3D objects (http://kenney.itch.io/kenney-donation),
# but should work with any other OBJ files.
# This is a batch script, run in a folder containing at least one 3d .obj file as follows:
# blender -b -P VertexPaintMaterials.py

for obj in glob.glob('*.obj'):
    bpy.ops.import_scene.obj(filepath=obj)
    mesh = bpy.data.objects[len(bpy.data.objects) - 1]
    # Scale by 32 units
    mesh.matrix_basis = mesh.matrix_basis * mathutils.Matrix.Scale(32,4)
    bpy.context.scene.objects.active = mesh
    # Apply transforms
    bpy.ops.object.transform_apply(location=True, rotation=True, scale=True)
    mesh.data.use_paint_mask = True
    for uv_layer in mesh.data.uv_layers:
        bpy.ops.mesh.uv_texture_remove()
    if len(mesh.data.vertex_colors)==0:
        bpy.ops.mesh.vertex_color_add()
    for i in range(0,len(mesh.data.materials)):
        bpy.ops.object.mode_set(mode='EDIT')
        mesh.active_material_index = i
        bpy.ops.mesh.select_all(action='SELECT')
        bpy.ops.mesh.quads_convert_to_tris()
        bpy.ops.mesh.tris_convert_to_quads()
        bpy.ops.mesh.select_all(action='DESELECT')
        bpy.ops.object.material_slot_select()
        bpy.ops.object.mode_set(mode='VERTEX_PAINT')
        bpy.data.brushes["Draw"].color = mesh.data.materials[i].diffuse_color
        bpy.ops.paint.vertex_color_set()
        bpy.ops.object.mode_set(mode='EDIT')
        bpy.ops.object.material_slot_deselect()
    bpy.ops.export_mesh.msh(filepath=obj.replace('.obj',''))