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mesh.rotate_*( ) & mesh.translate( ) move camera even though camera.position is specified

See original GitHub issue

Describe the bug, what’s wrong, and what you expected.

When applying rotations or translations to meshes, it seems like the camera moves around even though a camera.position is specified. This seems like undesired behaviour, as when I specify a camera I would like it to be fixed and not be influenced by a mesh being rotated or translated. Seems like even the axis changes sometimes (couldn’t get a screenshot this time).

Steps to reproduce the bug.

from pyvista import examples
filename = examples.planefile
plane = pv.read(filename)

# Alternate between different translations and rotations here
plane_mesh = plane.translate((100, 0, 100), inplace=False)
plane_mesh = plane_mesh.rotate_z(-30, inplace=False)

p = pv.Plotter()
p.show_axes()
p.add_mesh(plane, color=True, show_edges=True, opacity=0.5)
p.add_mesh(plane_mesh, color=True, show_edges=True, opacity=0.5)
p.camera.position = (0, 3000, 2000)
p.show()

System Information

--------------------------------------------------------------------------------
  Date: Tue Aug 16 12:06:34 2022 CEST

                OS : Darwin
            CPU(s) : 8
           Machine : x86_64
      Architecture : 64bit
               RAM : 16.0 GiB
       Environment : Jupyter
       File system : apfs
        GPU Vendor : ATI Technologies Inc.
      GPU Renderer : AMD Radeon Pro 560 OpenGL Engine
       GPU Version : 4.1 ATI-4.8.54

  Python 3.7.12 | packaged by conda-forge | (default, Oct 26 2021, 05:57:50)
  [Clang 11.1.0 ]

           pyvista : 0.36.1
               vtk : 9.1.0
             numpy : 1.21.6
           imageio : 2.21.1
           appdirs : 1.4.4
            scooby : 0.5.12
        matplotlib : 3.5.2
           IPython : 7.33.0
          colorcet : 3.0.0
           cmocean : 2.0
        ipyvtklink : 0.2.2
             scipy : 1.7.3
              tqdm : 4.64.0
            meshio : 5.3.4
        jupyterlab : 3.4.4
--------------------------------------------------------------------------------

Screenshots

Issue Analytics

State:
Created a year ago
Comments:6 (3 by maintainers)

Top GitHub Comments

1reaction

MatthewFlammcommented, Aug 17, 2022

Sorry actually this sets the focal point on the centre of the original plane, but does it have to be dependent on a mesh? Or can it be set to the global origin instead?

In my example, plane.center is a sequence (X, Y, Z). You can use any point in space. Try (0, 0, 0) to use the world origin.

1reaction

MatthewFlammcommented, Aug 16, 2022

You have set the camera position, but have allowed the focal point of the camera to adjust based on the scene. Does the below do what you want? It sets the focal point on the center of the original plane.

from pyvista import examples
filename = examples.planefile
plane = pv.read(filename)

# Alternate between different translations and rotations here
plane_mesh = plane.translate((100, 0, 100), inplace=False)
plane_mesh = plane_mesh.rotate_z(-30, inplace=False)

p = pv.Plotter()
p.show_axes()
p.add_mesh(plane, color='red', show_edges=True, opacity=0.5)
p.add_mesh(plane_mesh, color='blue', show_edges=True, opacity=0.5)
p.camera.position = (0, 3000, 2000)
p.camera.focal_point = plane.center
p.show()