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 = {}){
        super();
        var _opts_halfExtents;
        // Check the supplied options and provide defaults for unspecified ones
        var he = (_opts_halfExtents = opts.halfExtents) != null ? _opts_halfExtents : new Vec2(0.5, 0.5);
        var _opts_widthSegments;
        var ws = (_opts_widthSegments = opts.widthSegments) != null ? _opts_widthSegments : 5;
        var _opts_lengthSegments;
        var ls = (_opts_lengthSegments = opts.lengthSegments) != null ? _opts_lengthSegments : 5;
        // Variable declarations
        var positions = [];
        var normals = [];
        var uvs = [];
        var 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
        var vcounter = 0;
        for(var i = 0; i <= ws; i++){
            for(var j = 0; j <= ls; j++){
                var x = -he.x + 2 * he.x * i / ws;
                var y = 0.0;
                var z = -(-he.y + 2 * he.y * j / ls);
                var u = i / ws;
                var 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 };