Cancellable measurements

[xeolabs]

Addresses #1480

Extends controls for all measurements plugins; adds behaviour to the reset methods on measurements controls to destroy any measurement that is currently being constructed.

Adds reset action to context menus for examples.

Usage

The following example shows how reset is used with DistanceMeasurementsMouseControl. This is the same for all mouse and touch controls for other measurements plugins as well.

import {Viewer, XKTLoaderPlugin, ContextMenu, DistanceMeasurementsPlugin, DistanceMeasurementsMouseControl, PointerLens} from "../../dist/xeokit-sdk.es.js";

    const viewer = new Viewer({
        canvasId: "myCanvas",
        dtxEnabled: true
    });

   //...

    const distanceMeasurementsPlugin = new DistanceMeasurementsPlugin(viewer);

    //...
    
    const distanceMeasurementsMouseControl = new 
        DistanceMeasurementsMouseControl(distanceMeasurementsPlugin, {
        })

    //...

    distanceMeasurementsMouseControl.activate();

   //..

    // Resets control and destroys any measurement currently in progress
    
    distanceMeasurementsMouseControl.reset();

Example:

• https://xeokit.github.io/xeokit-sdk/examples/measurement/#distance_createWithMouse_snapping