@polygonjs/polygonjs/src/core/geometry/modules/three/builders/_Base.ts

node-based WebGL 3D engine https://polygonjs.com

import {Vector3, BufferGeometry, Float32BufferAttribute} from 'three';
import {BaseCorePoint} from '../../../entities/point/CorePoint';
import {uniqWithoutPreservingOrder, arrayCompact} from '../../../../ArrayUtils';
import {PolyDictionary} from '../../../../../types/GlobalTypes';
import {CoreObjectType, ObjectContent} from '../../../ObjectContent';

export abstract class CoreGeometryBuilderBase {
	fromPoints<T extends CoreObjectType>(object: ObjectContent<T>, points: BaseCorePoint[]): BufferGeometry {
		points = this._filterPoints(points);
		const geometry = new BufferGeometry();
		// const coreGeometry = new CoreGeometry(geometry);

		const firstPoint = points[0];
		if (!firstPoint) {
			return geometry;
		}
		const oldGeometry = firstPoint.geometry();
		if (!oldGeometry) {
			return geometry;
		}

		// index
		const new_index_by_old_index: PolyDictionary<number> = {};
		for (let i = 0; i < points.length; i++) {
			new_index_by_old_index[points[i].index()] = i;
		}

		const indices = this._indicesFromPoints(new_index_by_old_index, oldGeometry);
		if (indices) {
			geometry.setIndex(indices);
		}

		// attributes
		const {attributes} = oldGeometry;
		// const new_attributes = {}
		for (const attribute_name of Object.keys(attributes)) {
			const attrib_values = firstPoint.userDataAttribs()[attribute_name];
			const is_attrib_indexed = attrib_values != null;

			if (is_attrib_indexed) {
				const new_values: string[] = [];
				const uniqValues: string[] = [];
				uniqWithoutPreservingOrder(
					points.map((point) => point.indexedAttribValue(attribute_name)),
					uniqValues
				);
				arrayCompact(uniqValues, new_values);
				const new_index_by_value: PolyDictionary<number> = {};
				new_values.forEach((new_value, i) => (new_index_by_value[new_value] = i));

				firstPoint.userDataAttribs()[attribute_name] = new_values;

				// const old_attrib = old_geometry.getAttribute(attribute_name)
				// const old_attrib_array = old_attrib.array
				const new_attrib_indices = [];
				for (const point of points) {
					// const old_index = old_attrib_array[point.index()]
					const oldIndex = point.indexedAttribValue(attribute_name);
					if (oldIndex) {
						const new_index = new_index_by_value[oldIndex];
						new_attrib_indices.push(new_index);
					}
				}

				geometry.setAttribute(attribute_name, new Float32BufferAttribute(new_attrib_indices, 1));
			} else {
				const attrib_size = attributes[attribute_name].itemSize;
				const values: number[] = new Array(points.length * attrib_size);
				switch (attrib_size) {
					case 1:
						for (let i = 0; i < points.length; i++) {
							values[i] = points[i].attribValue(attribute_name) as number;
						}
						break;
					default:
						let value: Vector3;
						for (let i = 0; i < points.length; i++) {
							value = points[i].attribValue(attribute_name) as Vector3;
							value.toArray(values, i * attrib_size);
						}
						break;
				}

				geometry.setAttribute(attribute_name, new Float32BufferAttribute(values, attrib_size));
			}
		}
		return geometry;
	}

	protected abstract _filterPoints(points: BaseCorePoint[]): BaseCorePoint[];
	protected abstract _indicesFromPoints(
		new_index_by_old_index: PolyDictionary<number>,
		old_geometry: BufferGeometry
	): number[] | undefined;
}