Measure distances in 3D

Example to do measurements in a 3D scene. Click on the surface of the two objects to see the distance betweeen these points.

import numpy as np
import imageio.v3 as iio
from rendercanvas.auto import RenderCanvas, loop
import pygfx as gfx


canvas = RenderCanvas()
renderer = gfx.renderers.WgpuRenderer(canvas)
scene = gfx.Scene()

im = iio.imread("imageio:bricks.jpg")
tex = gfx.Texture(im, dim=2)

geometry = gfx.torus_knot_geometry(1, 0.3, 128, 32)
geometry.texcoords.data[:, 0] *= 10  # stretch the texture
material = gfx.MeshPhongMaterial(map=tex, pick_write=True)

obj1 = gfx.Mesh(geometry, material)
obj2 = gfx.Mesh(geometry, material)
obj1.local.x = -3
obj2.local.x = 3
scene.add(obj1, obj2)

ruler = gfx.Ruler(ticks_at_end_points=True)
scene.add(ruler)

camera = gfx.PerspectiveCamera(70, 1)
camera.show_object(scene)

scene.add(gfx.AmbientLight(), camera.add(gfx.DirectionalLight()))

controller = gfx.OrbitController(camera, register_events=renderer)


@obj1.add_event_handler("pointer_down")
@obj2.add_event_handler("pointer_down")
def handle_clicks(event):
    if event.target is obj1 or event.target is obj2:
        face_index = event.pick_info["face_index"]
        face_coord = event.pick_info["face_coord"]
        vertex_indices = geometry.indices.data[face_index]
        pos = np.sum(
            [
                geometry.positions.data[i] * w
                for i, w in zip(vertex_indices, face_coord, strict=True)
            ],
            axis=0,
        )
        pos += event.target.world.position

        if event.target is obj1:
            ruler.start_pos = pos
        else:
            ruler.end_pos = pos


def animate():
    ruler.update(camera, canvas.get_logical_size())
    renderer.render(scene, camera)


if __name__ == "__main__":
    canvas.request_draw(animate)
    loop.run()

Interactive example

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