Mesh slice

Example to validate the mesh slice rendering.

This particular configuration is a sphere with a dent in it, which displayed multiple different artifacts (missing line pieces and spurious points) with the initial mesh-slice implementation. By making this a validation example we avoid regressions w.r.t. these artifacts.

import base64

import numpy as np
from wgpu.gui.auto import WgpuCanvas, run
import pygfx as gfx


canvas = WgpuCanvas()
renderer = gfx.renderers.WgpuRenderer(canvas)


# Data - base64 is a little more compact than array literals.

positions_encoded = """
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"""

faces_encoded = """
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"""

positions_bytes = base64.decodebytes(positions_encoded.strip().encode())
faces_bytes = base64.decodebytes(faces_encoded.strip().encode())

positions = np.frombuffer(positions_bytes, np.float32).reshape(-1, 3)
faces = np.frombuffer(faces_bytes, np.int32).reshape(-1, 3)


# Vis

scene = gfx.Scene()

# Add color and texcoords. These are not used, but it means that all
# color_mode's are supported and can quickly be tested.
# NOTE: when showing a color per face, some line pieces are split into two colors.
# This is because the plane runs exactly over an edge in the mesh, so the observed
# line piece has contributions from two faces.
coords = np.linspace(0, 1, len(faces), dtype=np.float32)
colors = np.random.uniform(0, 1, (len(faces), 4)).astype(np.float32)
colors[:, 3] = 1
map = gfx.cm.viridis

mesh = gfx.Mesh(
    gfx.Geometry(positions=positions, indices=faces, colors=colors, texcoords=coords),
    gfx.MeshSliceMaterial(thickness=10, color="cyan", map=map, color_mode="uniform"),
)
mesh.material.plane = -1, 0, 0, 0  # yz
scene.add(mesh)

camera = gfx.OrthographicCamera(5, 5)
camera.show_object(scene, view_dir=(-1, 0, 0), up=(0, 0, 1))

canvas.request_draw(lambda: renderer.render(scene, camera))


@mesh.add_event_handler("pointer_move")
def show_pick_coords(e):
    print("face:", e.pick_info["face_index"], ":", e.pick_info["face_coord"])


if __name__ == "__main__":
    print(__doc__)
    run()