dots_on_screenshot.py

import bpy
from mathutils import Vector, Matrix
from bpy_extras import view3d_utils
import bmesh
import numpy as np
import os, sys
import cv2



context = bpy.context
scene = context.scene
ob = context.object
mw = ob.matrix_world
me = ob.data

def region_3d(context):
    for area in context.screen.areas:
        if area.type == 'VIEW_3D':
            space = area.spaces.active
            r3d = space.region_3d
            plane_no = r3d.view_rotation @ Vector((0, 0, -1))
            region = area.regions[-1]
            break
    else:
        assert False, "Requires a $D view"
    return region, r3d, area


def vertex_positions_2d(obj, region, r3d):
    bm = bmesh.new()
    bm.from_mesh(obj.data)
    bm.transform(obj.matrix_world)
    
    v_2d_co = np.array(
        [view3d_utils.location_3d_to_region_2d(
            region,
            r3d,
            v.co) for v in bm.verts]
    )
    return v_2d_co

def screenshot(P_filename, P_path = None):
  import bpy

  L_saveAs = P_filename
  L_saveAs = os.path.join(P_path, L_saveAs) if P_path else os.path.join("/tmp", L_saveAs)
  print("Scene saved in " + L_saveAs)

  #XXX: switching to 3D full view = maximize scene in main window
  #bpy.context.window.screen = bpy.data.screens['3D View Full']
  for window in bpy.context.window_manager.windows:
    screen = window.screen
    for area in screen.areas:
      if area.type == 'VIEW_3D':
        for space in area.spaces:
          if space.type == 'VIEW_3D':
            for region in area.regions:
              if region.type == 'WINDOW':
                L_altBpyCtx = {
                    'area' : area, 'blend_data': bpy.context.blend_data, 'region' : None, 'scene' : window.scene, 'space' : space,
                    'screen' : window.screen, 'window' : window
                }
                bpy.ops.screen.screenshot(L_altBpyCtx, filepath = L_saveAs, full = False)
                break
            break
        break


region, r3d, area = region_3d(context)
print(region, r3d)
positions=vertex_positions_2d(ob, region, r3d)

screenshot('screenshotto.png', '.')

def put_dots(img_path, positions):
    img = cv2.imread(img_path, cv2.IMREAD_UNCHANGED) 
    red = [0,0,255]
    height, width, channels = img.shape
    for p in positions:
        # print(p, p[0], p[1])
        cv2.circle(img, (round(p[0]), height - round(p[1])), 6, (0,0,255), -1)
    cv2.imwrite('./foo.jpg', img)
    pass

put_dots('./screenshotto.png', positions)