Demo Modules 003

Factory functions to create more complex, compound entitys

Related files:

The entity ring factory

This factory takes a single items Javascript Object argument (to match the functionality of built-in Scrawl-canvas factories). Four of the attributes of this argument object are required, the others will fall back on default values. These attrributes are:

canvas (required) - Scrawl-canvas Canvas wrapper object - the canvas which will be hosting the compound entity we are about to create

namespace (required) - String - unique name value

entity (required) - Scrawl-canvas entity object - any valid entity that has already been created

scrawl (required) - Scrawl-canvas object

dimensions - Number - the square dimensions of the compound entity; default: 400

buildStartAngle - Number - the angle of the first entity we lay down; default: -45

buildEndAngle - Number - the angle of the last entity we lay down - note that this needs to be sufficient to cover at least half of the ring, which we can then copy and stamp to create the final output; default: 225

buildStepAngle - Number - the repeat value - higher values lead to fewer entitys making up the final ring; default: 15

buildOffset - Number - the entity’s offset from the center of the ring (as measured in px); default: 0

reflectOnly - Boolean - when the ring half is copied and pasted back into the final output, it can be set to reflect only, which will give us a bilateral rather than a radial symmetry; default: false

export default function (items = {}) {

    const { canvas, namespace, entity, scrawl } = items;

    if (!(canvas && entity && namespace && scrawl)) return {};

    const name = item => `${namespace}-${item}`;

    const {
        dimensions = 400,
        buildStartAngle = -45,
        buildEndAngle = 225,
        buildStepAngle = 15,
        buildOffset = 0,
        reflectOnly = false,
    } = items;

    const cell = canvas.buildCell({
        name: name('cell'),
        dimensions: [dimensions, dimensions],
        shown: false,
    });

    scrawl.makeGroup({
        name: name('clip-group'),
        host: name('cell'),
        order: 0,
    });

    scrawl.makeGroup({
        name: name('reflect-group'),
        host: name('cell'),
        order: 1,
    });

    scrawl.makeBlock({
        name: name('clipper'),
        group: name('clip-group'),
        start: ['left', 'center'],
        dimensions: ['100%', '50%'],
        method: 'clip'
    });

    const v = scrawl.requestVector(0, buildOffset);
    v.rotate(buildStartAngle);

    for (let i = buildStartAngle; i <= buildEndAngle; i += buildStepAngle) {

        entity.clone({
            name: name(`ringitem-${i}`),
            group: name('clip-group'),
            roll: i,
            offset: [v.x, v.y],
        });

        v.rotate(buildStepAngle);
    }

    scrawl.releaseVector(v);

    scrawl.makePicture({
        name: name('reflection'),
        group: name('reflect-group'),
        asset: name('cell'),

        start: ['center', '25%'],
        handle: ['center', 'center'],
        flipUpend: true,
        flipReverse: !reflectOnly,

        dimensions: ['100%', '50%'],
        copyDimensions: ['100%', '50%'],
        copyStartY: '50%',

        method: 'fill',
    });

    entity.set({
        visibility: false,
    });

    return {
        cell,
        kill: () => scrawl.purge(namespace),
    }
}