"""A cut along the ship's centre line, looking to starboard (nothing is saved):
blender -b --factory-startup <file.blend> --python section.py -- <out.png> <x0> <x1> <z0> <z1> <px wide>"""
import sys

import bpy
from mathutils import Vector

a = sys.argv[sys.argv.index("--") + 1:]
import os
OUT, X0, X1, Z0, Z1, PX = a[0], float(a[1]), float(a[2]), float(a[3]), float(a[4]), int(a[5])
OUT = os.path.abspath(OUT)                 # (Blender resolves a relative render path against a drive root)
sc = bpy.context.scene
for eng in ("BLENDER_EEVEE_NEXT", "BLENDER_EEVEE"):
    try:
        sc.render.engine = eng
        break
    except TypeError:
        pass
cam_d = bpy.data.cameras.new("section")
cam_d.type = "ORTHO"
cam_d.ortho_scale = X1 - X0
cam_d.clip_start = 0.01
cam_d.clip_end = 40.0
cam = bpy.data.objects.new("section", cam_d)
sc.collection.objects.link(cam)
cam.location = ((X0 + X1) / 2.0, 0.02, (Z0 + Z1) / 2.0)
cam.rotation_euler = Vector((0.0, -1.0, 0.0)).to_track_quat("-Z", "Y").to_euler()
sc.camera = cam
sc.render.resolution_x = PX
sc.render.resolution_y = int(round(PX * (Z1 - Z0) / (X1 - X0)))
sc.render.resolution_percentage = 100
sc.render.filepath = OUT
sc.render.image_settings.file_format = "PNG"
w = bpy.data.worlds.new("section")
w.use_nodes = True
w.node_tree.nodes["Background"].inputs["Color"].default_value = (0.75, 0.80, 0.86, 1.0)
w.node_tree.nodes["Background"].inputs["Strength"].default_value = 1.6
sc.world = w
# lamps off: the cut is shown in even light
for o in sc.objects:
    if o.type == "LIGHT":
        o.hide_render = True
    if o.name.startswith(("MARKER | ",)):
        o.hide_render = True
bpy.ops.render.render(write_still=True)
print("[section] wrote", OUT, sc.render.resolution_x, sc.render.resolution_y)