centroid Expression

Doc > Expressions > centroid

Returns the centroid of a geometry, or the component of the centroid.

Description

It takes 1 or 2 arguments.

centroid(<input_index_or_node_path>, <vector_component>)

<input_index_or_node_path> is a number or a string
<vector_component> is a string, either 'x', 'y' or 'z'

Usage

centroid(0) - returns the centroid of the input node, as a THREE.Box3
centroid('/geo1/box') - returns the centroid of the node /geo1/box, as a THREE.Box3
centroid('/geo1/box', 'x') - returns the x component of centroid of the bbox, as a number


// create a scene
const scene = new PolyScene();
const root = scene.root();

// create a box and a sphere
const geo = root.createNode('geo');
const box = geo.createNode('box');
const torus = geo.createNode('torus');
const transform = geo.createNode('transform');
const noise = geo.createNode('noise');
const merge = geo.createNode('merge');

noise.setInput(0, torus);
transform.setInput(0, box);
merge.setInput(0, noise);
merge.setInput(1, transform);
merge.flags.display.set(true);

torus.p.radiusTube.set(0.1);
torus.p.segmentsRadial.set(10);
torus.p.segmentsTube.set(30);

noise.p.amplitude.set(0.7);
noise.p.freq.set([0.3, 0.3, 0.3]);
noise.p.offset.y.set('$T');

box.p.size.set(0.25);

transform.p.t.x.set(`centroid('../${noise.name()}').x`);
transform.p.t.z.set(`centroid('../${noise.name()}').z`);

// add a light
root.createNode('hemisphereLight');

// create a camera
const perspectiveCamera1 = root.createNode('perspectiveCamera');
perspectiveCamera1.p.t.set([5, 5, 5]);
// add orbitControls
const events1 = perspectiveCamera1.createNode('eventsNetwork');
const orbitsControls = events1.createNode('cameraOrbitControls');
perspectiveCamera1.p.controls.setNode(orbitsControls);

// play
scene.play();

// mount the viewer
const element = document.getElementById('app');
perspectiveCamera1.createViewer(element);