Function points

Track several named points over time, eg a TensorFlow body pose point. Call seen() to track a point. Mutable. If you want to compare a single coordinate with a reference coordinate, point may be a better choice.

See also:

• Geometry.Points.relation: Compute relation info between two points
• Trackers.point: Track relation between points over time
• ixfx Guide to Point Tracker

Basic usage

import { points } from 'https://unpkg.com/ixfx/dist/trackers.js';

const pt = points();

// Track a point under a given id
document.addEventListener(`pointermove`, e => {
 const info = await pt.seen(e.pointerId, { x: e.x, y: e.y });
 // Yields some info on relation of the point to initial value
});
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Do something with last values for all points

const c = Points.centroid(...Array.from(pt.last()));
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More functions...

pt.size;       // How many named points are being tracked
pt.delete(id); // Delete named point
pt.reset();    // Clear data
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Accessing by id:

pt.get(id);  // Get named point (or _undefined_)
pt.has(id);  // Returns true if id exists
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Iterating over data

pt.trackedByAge(); // Iterates over tracked points, sorted by age (oldest first)
pt.tracked(); // Tracked values
pt.ids();     // Iterator over ids

// Last received value for each named point
pt.last();

pt.initialValues(); // Iterator over initial values for each point
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You can work with 'most recently updated' points:

// Iterates over points, sorted by age (oldest first)
pt.valuesByAge();
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Options:

• id: Id of this tracker. Optional
• sampleLimit: How many samples to store
• storeIntermediate: If true, all points are stored internally
• resetAfterSamples: If set above 0, it will automatically reset after the given number of samples have been seen