extrude_mesh.gd

func extrude(bevel: Array, path: Path):
  # Bevel is your cross section, it's an array of Vector3
  # Path is the curve we're following

  var resolution = 1.0

  var curve: Curve3D = path.curve
  var length: float = curve.get_baked_length()
  var steps: int = floor(length / resolution)
  var offset: float = length / steps
  var bevel_count: int = bevel.size()
  var up = Vector3(0, 1, 0)
  
  var surface_tool := SurfaceTool.new()
  surface_tool.begin(Mesh.PRIMITIVE_TRIANGLES);
  surface_tool.add_smooth_group(true)
  
  for i in range(steps + 1):
    var current_offset: float = i * offset
    var position_on_curve: Vector3 = curve.interpolate_baked(current_offset)

    var position_2: Vector3
    if current_offset + 0.1 < length:
      position_2 = curve.interpolate_baked(current_offset + 0.1)
    else:
      position_2 = curve.interpolate_baked(current_offset - 0.1)
      position_2 += (position_on_curve - position_2) * 2.0

    var node = Spatial.new()

    node.look_at_from_position(position_on_curve, position_2, up)
    up = node.transform.basis.y

    for j in range(bevel_count):

      var pos = bevel.points[j]
      pos = node.transform.xform(pos)

      surface_tool.add_color(Color(1, 1, 1, 1));
      surface_tool.add_vertex(pos)

    if i > 0:
      for k in range(bevel_count - 1):
        surface_tool.add_index((i - 1) * bevel_count + k)
        surface_tool.add_index((i - 1) * bevel_count + k + 1)
        surface_tool.add_index(i * bevel_count + k)

        surface_tool.add_index(i * bevel_count + k)
        surface_tool.add_index((i - 1) * bevel_count + k + 1)
        surface_tool.add_index(i * bevel_count + k + 1)

  node.queue_free()

  surface_tool.generate_normals()

  var mesh_instance = MeshInstance.new()
  mesh_instance.transform = path.transform
  mesh_instance.mesh = surface_tool.commit()
  
  return mesh_instance