Wireframe without mesh not showing up if no meshes are defined

[jfslin]

I tried loading the following double pendulum Lua model and was expecting to see the wireframe, but instead got a blank screen. No error messages shown.

Probably not urgent since the tutorial will show how to incorporate standard meshes so it's less of a concern, I think.

rod_length = 1

model = {
  gravity = { 0, -9.81, 0 },

  configuration = {
    axis_right = { 1, 0, 0 },
    axis_front = { 0, 1, 0 },
    axis_up =    { 0, 0, 1 },
  },

  frames = {
    {
      name = "segment1",
      parent = "ROOT",
      visuals = { meshes.rod1 },
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    },
    {
      name = "segment2",
      parent = "segment1",
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        r = { 0., 0., -rod_length },
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    },
    {
      name = "segment3",
      parent = "segment1",
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        r = { 0., 0., rod_length },
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    }
  }
}

return model

Loading the proper meshes did provide the wireframe though:

rod_length = 1

meshes = {
  rod1 = {
    color = { 1, 0, 0},
    mesh_center = {0, 0, -rod_length/2},
    dimensions = { 0.1, 0.1, rod_length},
    src = "unit_cube.obj"
  },
  rod2 = {
    color = { 0, 1, 0},
    mesh_center = {0, 0, -rod_length/2},
    dimensions = { 0.1, 0.1, rod_length},
    src = "unit_cube.obj"
  }
}

model = {
  gravity = { 0, -9.81, 0 },

  configuration = {
    axis_right = { 1, 0, 0 },
    axis_front = { 0, 1, 0 },
    axis_up =    { 0, 0, 1 },
  },

  frames = {
    {
      name = "segment1",
      parent = "ROOT",
      visuals = { meshes.rod1 },
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    },
    {
      name = "segment2",
      parent = "segment1",
      visuals = { meshes.rod2 },
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        r = { 0., 0., -rod_length },
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    },
    {
      name = "segment3",
      parent = "segment1",
      visuals = { meshes.rod2 },
      joint = {{ 0, 1, 0, 0, 0, 0 }},
      joint_frame = {
        r = { 0., 0., rod_length },
        E = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}}
      }
    }
  }
}

return model