@openhps/core/src/three/core/GLBufferAttribute.js

Open Hybrid Positioning System - Core component

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.GLBufferAttribute = void 0;
/**
 * An alternative version of a buffer attribute with more control over the VBO.
 *
 * The renderer does not construct a VBO for this kind of attribute. Instead, it uses
 * whatever VBO is passed in constructor and can later be altered via the `buffer` property.
 *
 * The most common use case for this class is when some kind of GPGPU calculation interferes
 * or even produces the VBOs in question.
 *
 * Notice that this class can only be used with {@link WebGLRenderer}.
 */
class GLBufferAttribute {
  /**
   * Constructs a new GL buffer attribute.
   *
   * @param {WebGLBuffer} buffer - The native WebGL buffer.
   * @param {number} type - The native data type (e.g. `gl.FLOAT`).
   * @param {number} itemSize - The item size.
   * @param {number} elementSize - The corresponding size (in bytes) for the given `type` parameter.
   * @param {number} count - The expected number of vertices in VBO.
   */
  constructor(buffer, type, itemSize, elementSize, count) {
    /**
     * This flag can be used for type testing.
     *
     * @type {boolean}
     * @readonly
     * @default true
     */
    this.isGLBufferAttribute = true;

    /**
     * The name of the buffer attribute.
     *
     * @type {string}
     */
    this.name = '';

    /**
     * The native WebGL buffer.
     *
     * @type {WebGLBuffer}
     */
    this.buffer = buffer;

    /**
     * The native data type.
     *
     * @type {number}
     */
    this.type = type;

    /**
     * The item size, see {@link BufferAttribute#itemSize}.
     *
     * @type {number}
     */
    this.itemSize = itemSize;

    /**
     * The corresponding size (in bytes) for the given `type` parameter.
     *
     * @type {number}
     */
    this.elementSize = elementSize;

    /**
     * The expected number of vertices in VBO.
     *
     * @type {number}
     */
    this.count = count;

    /**
     * A version number, incremented every time the `needsUpdate` is set to `true`.
     *
     * @type {number}
     */
    this.version = 0;
  }

  /**
   * Flag to indicate that this attribute has changed and should be re-sent to
   * the GPU. Set this to `true` when you modify the value of the array.
   *
   * @type {number}
   * @default false
   * @param {boolean} value
   */
  set needsUpdate(value) {
    if (value === true) this.version++;
  }

  /**
   * Sets the given native WebGL buffer.
   *
   * @param {WebGLBuffer} buffer - The buffer to set.
   * @return {BufferAttribute} A reference to this instance.
   */
  setBuffer(buffer) {
    this.buffer = buffer;
    return this;
  }

  /**
   * Sets the given native data type and element size.
   *
   * @param {number} type - The native data type (e.g. `gl.FLOAT`).
   * @param {number} elementSize - The corresponding size (in bytes) for the given `type` parameter.
   * @return {BufferAttribute} A reference to this instance.
   */
  setType(type, elementSize) {
    this.type = type;
    this.elementSize = elementSize;
    return this;
  }

  /**
   * Sets the item size.
   *
   * @param {number} itemSize - The item size.
   * @return {BufferAttribute} A reference to this instance.
   */
  setItemSize(itemSize) {
    this.itemSize = itemSize;
    return this;
  }

  /**
   * Sets the count (the expected number of vertices in VBO).
   *
   * @param {number} count - The count.
   * @return {BufferAttribute} A reference to this instance.
   */
  setCount(count) {
    this.count = count;
    return this;
  }
}
exports.GLBufferAttribute = GLBufferAttribute;