@animech-public/playcanvas/build/playcanvas.dbg/src/scene/geometry/plane-geometry.js

PlayCanvas WebGL game engine

import { Vec2 } from '../../core/math/vec2.js';
import { calculateTangents } from './geometry-utils.js';
import { Geometry } from './geometry.js';

/**
 * A procedural plane-shaped geometry.
 *
 * The size and tesselation properties of the plane can be controlled via constructor parameters. By
 * default, the function will create a plane centered on the object space origin with a width and
 * length of 1.0 and 5 segments in either axis (50 triangles). The normal vector of the plane is
 * aligned along the positive Y axis.
 *
 * Note that the plane is created with UVs in the range of 0 to 1.
 *
 * @category Graphics
 */
class PlaneGeometry extends Geometry {
  /**
   * Create a new PlaneGeometry instance.
   *
   * @param {object} [opts] - An object that specifies optional inputs for the function as follows:
   * @param {Vec2} [opts.halfExtents] - The half dimensions of the plane in the X and Z axes
   * (defaults to [0.5, 0.5]).
   * @param {number} [opts.widthSegments] - The number of divisions along the X axis of the plane
   * (defaults to 5).
   * @param {number} [opts.lengthSegments] - The number of divisions along the Z axis of the plane
   * (defaults to 5).
   * @param {boolean} [opts.calculateTangents] - Generate tangent information (defaults to false).
   */
  constructor(opts = {}) {
    var _opts$halfExtents, _opts$widthSegments, _opts$lengthSegments;
    super();

    // Check the supplied options and provide defaults for unspecified ones
    const he = (_opts$halfExtents = opts.halfExtents) != null ? _opts$halfExtents : new Vec2(0.5, 0.5);
    const ws = (_opts$widthSegments = opts.widthSegments) != null ? _opts$widthSegments : 5;
    const ls = (_opts$lengthSegments = opts.lengthSegments) != null ? _opts$lengthSegments : 5;

    // Variable declarations
    const positions = [];
    const normals = [];
    const uvs = [];
    const indices = [];

    // Generate plane as follows (assigned UVs denoted at corners):
    // (0,1)x---------x(1,1)
    //      |         |
    //      |         |
    //      |    O--X |length
    //      |    |    |
    //      |    Z    |
    // (0,0)x---------x(1,0)
    // width
    let vcounter = 0;
    for (let i = 0; i <= ws; i++) {
      for (let j = 0; j <= ls; j++) {
        const x = -he.x + 2 * he.x * i / ws;
        const y = 0.0;
        const z = -(-he.y + 2 * he.y * j / ls);
        const u = i / ws;
        const v = j / ls;
        positions.push(x, y, z);
        normals.push(0, 1, 0);
        uvs.push(u, 1 - v);
        if (i < ws && j < ls) {
          indices.push(vcounter + ls + 1, vcounter + 1, vcounter);
          indices.push(vcounter + ls + 1, vcounter + ls + 2, vcounter + 1);
        }
        vcounter++;
      }
    }
    this.positions = positions;
    this.normals = normals;
    this.uvs = uvs;
    this.uvs1 = uvs; // UV1 = UV0 for plane
    this.indices = indices;
    if (opts.calculateTangents) {
      this.tangents = calculateTangents(positions, normals, uvs, indices);
    }
  }
}

export { PlaneGeometry };