python tutorial: mesh sampler

python/tutorials/tutorial_401_mesh_sampler.py

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+# -----------------------------------------------------------------------------
+# Tutorial: Sampling a Surface Mesh into a Point Cloud
+# -----------------------------------------------------------------------------
+# This tutorial demonstrates how to:
+# 1. Use the Easy3D `SurfaceMeshSampler` class to sample points from a surface mesh.
+# 2. Visualize the original surface mesh and the sampled point cloud side-by-side
+#    using Easy3D's `MultiViewer`.
+# The sampling process generates a near-uniform distribution of points over the
+# surface of the mesh.
+# -----------------------------------------------------------------------------
+
+# If Easy3D is not installed via `pip` but built locally, add its Python bindings 
+# to the system path. For detailed instructions on building and installing 
+# Python bindings of Easy3D, visit:
+# https://github.com/LiangliangNan/Easy3D/blob/main/ReadMe.md
+import sys
+sys.path.append("../../cmake-build-release/lib/python")  # Update this path as needed.
+
+# Import the Easy3D library for 3D visualization and processing.
+import easy3d
+
+# Initialize the Easy3D library. The `False` parameter disables detailed logging.
+# Use `True` for more verbose output, which can be helpful for debugging.
+easy3d.initialize(False)
+
+# -----------------------------------------------------------------------------
+# Setting Up the Multi-View Viewer
+# -----------------------------------------------------------------------------
+# See detailed explanations in "python/tutorials/tutorial_203_multiview.py"
+
+# Create a MultiViewer instance with 1 row and 2 columns.
+viewer = easy3d.MultiViewer(1, 2, "Mesh Sampling Tutorial")
+viewer.set_usage("")
+
+# -----------------------------------------------------------------------------
+# Loading the Surface Mesh
+# -----------------------------------------------------------------------------
+# Load the Bunny surface mesh from a file. Ensure the file path is correct.
+mesh = viewer.add_model(easy3d.directory() + "/data/bunny.ply")
+# Assign the surface mesh to the left view (row=0, column=0).
+viewer.assign(0, 0, mesh)
+
+# -----------------------------------------------------------------------------
+# Sampling Points from the Surface Mesh
+# -----------------------------------------------------------------------------
+# Use the `SurfaceMeshSampler` class to sample points from the mesh surface.
+# The sampling process generates a near-uniform distribution of points.
+
+# Perform the sampling. 20000 is the desired number of points to sample.
+point_cloud = easy3d.SurfaceMeshSampler.apply(mesh, 20000)
+
+# Print the number of sampled points.
+print(f"Sampled point cloud with {point_cloud.n_vertices()} points.")
+
+# Add the sampled point cloud to the viewer and assign it to the right view (row=0, column=1).
+viewer.add_model(point_cloud)
+viewer.assign(0, 1, point_cloud)
+
+# Launch the viewer.
+viewer.run()
+
+# -----------------------------------------------------------------------------
+# Notes:
+# 1. The left view shows the original Bunny surface mesh.
+# 2. The right view shows the sampled point cloud with a near-uniform point
+#    distribution.
+# 3. Modify the `num_points` variable to experiment with different sampling densities.
+# -----------------------------------------------------------------------------