Notes

Running on Linux

If the viewer does not open, maybe libxcb-cursor0 is missing. Try installing (Ubuntu):

sudo apt install libxcb-cursor0

Also, if running wayland, the following should be added at the top of the file:

os.environ['QT_QPA_PLATFORM'] = 'xcb'

Running from shell

If not running from jupyter notebook, the viewer might close right away. To keep it interactive, run it with:

python -i file.py

Basic usage

import sdypy as sd

nodes = ... # Finite element nodes
elements ... # Finite elements

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements)
plotter.show(show_grid=True, show_axes=True)

To animate a mode shape:

mode_shape = ... # Shape (n_nodes, 3)

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements, animate=mode_shape)

To animate according to a time history:

time_history = ... # Shape (n_nodes, 3, n_timesteps)

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements, animate=time_history)

To color the mesh according to a norm of the mode_shape:

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements, animate=mode_shape, field="norm")

Here, if field="norm" is passed, the mesh will be colored according to the norm of the mode_shape (or more generally, according to the norm of the animate argument). To color the mesh according to an arbitrary field, the field argument must be of shape (n_nodes, n_timesteps).

Animation

The Plotter3D class also enables the user to animate the mesh. There are two way to animate the FEM mesh or points:

• By passing a 3D array of shape (n_nodes, 3, n_timesteps) to the animate argument. The points/nodes will be animated according to the time history.

• By passing a 2D array of shape (n_nodes, 3) to the animate argument. The animate defines the maximum displacement of the nodes. The animation is interpolated with a sine function.

The animate argument can also have the following shapes:

• (n_nodes*3): The Plotter3D will automatically convert this to (n_nodes, 3).

• (n_nodes*3, n_timesteps): The Plotter3D will automatically convert this to (n_nodes, 3, n_timesteps).

• (n_nodes*N): The Plotter3D will automatically convert this to (n_nodes, 3), where N is an arbitrary number. Only the first 3 columns are used. This is useful when animating e.g. a mode shape of a shell (each node has 6 DOF).

• (n_nodes*N, n_timesteps): The Plotter3D will automatically convert this to (n_nodes, 3, n_timesteps). Similar to previous point, but with time history.

The n_frames is set to 100 by default, but can be changed to alter the number of frames per one iteration. When providing the time history, the n_frames should match the last dimension of the animate argument.

Here is an example of animating a mode shape:

import sdypy as sd

nodes = ... # Finite element nodes (n_nodes, 3)
elements ... # Finite elements (n_elements, n_nodes_per_element)
mode_shape = ... # Mode shape (n_nodes, 3)

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements, animate=mode_shape, field="norm")

plotter.configure_animation(interval=20) # To adjust the interval and camera position
plotter.start_animation() # Optional. To immediately start the animation. Otherwise, the controls are available in the plotter.
plotter.show()

Recording a GIF

To record a GIF, the configure_gif_recorder method must be called. Example:

import sdypy as sd

nodes = ... # Finite element nodes (n_nodes, 3)
elements ... # Finite elements (n_elements, n_nodes_per_element)
mode_shape = ... # Mode shape (n_nodes, 3)

plotter = sd.view.Plotter3D(nodes, elements)

plotter.gif_recorder("mode_shape.gif") # MUST BE CALLED BEFORE THE ANIMATION STARTS

plotter.add_fem_mesh(nodes, elements, animate=mode_shape, field="norm")

plotter.configure_gif_recorder('mode_shape.gif', fps=30) # Configure the GIF recorder

plotter.show()

The recording will start on pressing the “Record” button in the toolbar. Alternatively, the configure_gif_recorder can be called like this:

plotter.configure_gif_recorder('mode_shape.gif', fps=30, start_on_play=True)

This will start the recording when the animation starts. To start the animation, call the start_animation method or press the “Play” button in the toolbar.

The recording will last for 1 iteration of the animation.

Adding custom toolbar buttons

To add custom toolbar commands, use the configure_toolbar method. Example:

import sdypy as sd

nodes = ... # Finite element nodes (n_nodes, 3)
elements ... # Finite elements (n_elements, n_nodes_per_element)
mode_shape = ... # Mode shape (n_nodes, 3)

plotter = sd.view.Plotter3D(nodes, elements)
plotter.add_fem_mesh(nodes, elements, animate=mode_shape, field="norm")

def custom_command():
    print("Custom command")

toolbar_actions = {
    "Custom command": custom_command
}

plotter.configure_toolbar(toolbar_actions)

plotter.show()