code: def __init__(self, pos=None, color=None, size=None):
      Visual.__init__(self, self.VERTEX_SHADER, self.FRAGMENT_SHADER)
      self._pos = pos
      self._color = color
      self._size = size
      self.set_gl_state(
          blend=True, blend_func=("src_alpha", "one_minus_src_alpha")
      )
      self._draw_mode = "points"
  
file_path: vispy/examples/basics/visuals/custom_visual.py
imports: from __future__ import division
  import numpy
  from vispy import app
  from vispy.gloo import VertexBuffer
  from vispy.visuals import Visual
  from vispy.visuals.transforms import STTransform
label_desc: Use image node_id 1 to create a new MarkerVisual object from inherited base classes: Visual with example: obj = MarkerVisual(pos, color, size)