Shadows

Demonstrate the usage of lights and shadows in PyVista.

# sphinx_gallery_thumbnail_number = 2
import pyvista
from pyvista import examples
import numpy as np

mesh = examples.download_dragon()
mesh.rotate_x(90)
mesh.rotate_z(120)

Using two lights, plot the Stanford Dragon with shadows.

Note

VTK has known issues when rendering shadows on certain window sizes. Be prepared to experiment with the window_size parameter. An initial window size of (1000, 1000) seems to work well, which can be manually resized without issue.

light1 = pyvista.Light(position=(0, 0.2, 1.0),
                       focal_point=(0, 0, 0),
                       color=[1, 1.0, 0.9843, 1],  # Color temp. 5400 K
                       intensity=0.3)

light2 = pyvista.Light(position=(0, 1.0, 1.0),
                       focal_point=(0, 0, 0),
                       color=[1, 0.83921, 0.6666, 1],  # Color temp. 2850 K
                       intensity=1)

# Add a thin box below the mesh
bounds = mesh.bounds
rnge = (bounds[1] - bounds[0],
        bounds[3] - bounds[2],
        bounds[5] - bounds[4])

expand = 1.0
height = rnge[2] * 0.05
center = np.array(mesh.center)
center -= [0, 0, mesh.center[2] - bounds[4] + height/2]

width = rnge[0]*(1 + expand)
length = rnge[1]*(1 + expand)
base_mesh = pyvista.Cube(center,
                         width,
                         length,
                         height)

# rotate base and mesh to get a better view
base_mesh.rotate_z(30)
mesh.rotate_z(30)

# create the plotter with custom lighting
pl = pyvista.Plotter(lighting=None, window_size=(800, 800))
pl.add_light(light1)
pl.add_light(light2)
pl.add_mesh(mesh, ambient=0.2, diffuse=0.5, specular=0.5, specular_power=90,
            smooth_shading=True, color='orange')
pl.add_mesh(base_mesh)
pl.enable_shadows()
pl.camera.zoom(1.5)
pl.show()

Out:

[(0.6794883905125556, 0.6682869492245612, 0.794861828736752),
 (0.0059667229652404785, -0.005234718322753906, 0.12134016118943691),
 (0.0, 0.0, 1.0)]

Show light penetrating several planes. Adjust the light intensity and the shadow_attenuation to change how many planes the light can go through.

plotter = pyvista.Plotter(lighting=None, window_size=(800, 800))

# add several planes
for plane_y in [2, 5, 10]:
    screen = pyvista.Plane(center=(0, plane_y, 0), direction=(0, 1, 0),
                           i_size=5, j_size=5)
    plotter.add_mesh(screen, color='white')

light = pyvista.Light(position=(0, 0, 0), focal_point=(0, 1, 0),
                      color='cyan', intensity=15, positional=True,
                      cone_angle=15, attenuation_values=(2, 0, 0))
light.show_actor()

plotter.add_light(light)
plotter.view_vector((1, -2, 2))
plotter.enable_shadows()
plotter.show()

Out:

[(7.886751345948129, -10.773502691896258, 15.773502691896258),
 (0.0, 5.0, 0.0),
 (0.0, 0.0, 1.0)]

Here, we use a lower shadow_attenuation value to demonstrate how the light can travel through more planes.

plotter = pyvista.Plotter(lighting=None, window_size=(800, 800))

# add several planes
for plane_y in [2, 5, 10]:
    screen = pyvista.Plane(center=(0, plane_y, 0), direction=(0, 1, 0),
                           i_size=5, j_size=5)
    plotter.add_mesh(screen, color='white')

light = pyvista.Light(position=(0, 0, 0), focal_point=(0, 1, 0),
                      color='cyan', intensity=15, cone_angle=15,
                      shadow_attenuation=0.95, positional=True,
                      attenuation_values=(2, 0, 0))
light.show_actor()

plotter.add_light(light)
plotter.view_vector((1, -2, 2))
plotter.enable_shadows()
plotter.show()

Out:

[(7.886751345948129, -10.773502691896258, 15.773502691896258),
 (0.0, 5.0, 0.0),
 (0.0, 0.0, 1.0)]