# Examples from pyvista.fit_line_to_points
# ========================================

# Download a point cloud. The points trace a path along topographical surface.
import pyvista as pv
from pyvista import examples
mesh = examples.download_gpr_path()

# Fit a line to the points and plot the result. The line of best fit is colored red.
line = pv.fit_line_to_points(mesh.points)

pl = pv.Plotter()
_ = pl.add_mesh(mesh, color='black', line_width=10)
_ = pl.add_mesh(line, color='red', line_width=5)
pl.show()

# Fit a line to a mesh and return the metadata.
mesh = examples.download_human()
line, length, direction = pv.fit_line_to_points(
    mesh.points, return_meta=True
)

# Show the length of the line.
length

# Plot the line as an arrow to show its direction.
arrow = pv.Arrow(
    start=line.points[0],
    direction=direction,
    scale=length,
    tip_length=0.2,
    tip_radius=0.04,
    shaft_radius=0.01,
)

pl = pv.Plotter()
_ = pl.add_mesh(mesh, opacity=0.5)
_ = pl.add_mesh(arrow, color='red')
pl.show()

# Set `init_direction` to the positive z-axis to flip the line's direction.
mesh = examples.download_human()
line, length, direction = pv.fit_line_to_points(
    mesh.points, init_direction='z', return_meta=True
)

# Plot the results again with an arrow.
arrow = pv.Arrow(
    start=line.points[0],
    direction=direction,
    scale=length,
    tip_length=0.2,
    tip_radius=0.04,
    shaft_radius=0.01,
)

pl = pv.Plotter()
_ = pl.add_mesh(mesh, opacity=0.5)
_ = pl.add_mesh(arrow, color='red')
pl.show()

# ----------------------------------------------------------------------
# Generated by sphinx-examples-as-code https://github.com/pyvista/sphinx-examples-as-code