@woosh/meep-engine/src/engine/graphics/geometry/buffered/makeGeometryIndexed.js

Pure JavaScript game engine. Fully featured and production ready.

import { BufferAttribute } from "three";
import { UintArrayForCount } from "../../../../core/collection/array/typed/uint_array_for_count.js";

/**
 *
 * @param {THREE.BufferGeometry} geometry
 * @return {THREE.BufferGeometry}
 */
export function makeGeometryIndexed(geometry) {
    let index_attribute = geometry.getIndex();

    if (index_attribute === null || index_attribute === undefined) {
        const position_attribute = geometry.getAttribute('position');
        // non-indexed geometry, build index
        const size = position_attribute.count;

        const UintArrayConstructor = UintArrayForCount(size);

        const array = new UintArrayConstructor(size);

        for (let i = 0; i < size; i++) {
            array[i] = i;
        }

        index_attribute = new BufferAttribute(array, 1, false);

        geometry.setIndex(index_attribute);
    }

    return geometry;
}