playcanvas/build/playcanvas/src/scene/geometry/box-geometry.js

Open-source WebGL/WebGPU 3D engine for the web

import { Vec3 } from "../../core/math/vec3.js";
import { calculateTangents } from "./geometry-utils.js";
import { Geometry } from "./geometry.js";
const primitiveUv1Padding = 8 / 64;
const primitiveUv1PaddingScale = 1 - primitiveUv1Padding * 2;
class BoxGeometry extends Geometry {
	constructor(opts = {}) {
		super();
		const he = opts.halfExtents ?? new Vec3(0.5, 0.5, 0.5);
		const ws = opts.widthSegments ?? 1;
		const ls = opts.lengthSegments ?? 1;
		const hs = opts.heightSegments ?? 1;
		const yOffset = opts.yOffset ?? 0;
		const minY = -he.y + yOffset;
		const maxY = he.y + yOffset;
		const corners = [
			new Vec3(-he.x, minY, he.z),
			new Vec3(he.x, minY, he.z),
			new Vec3(he.x, maxY, he.z),
			new Vec3(-he.x, maxY, he.z),
			new Vec3(he.x, minY, -he.z),
			new Vec3(-he.x, minY, -he.z),
			new Vec3(-he.x, maxY, -he.z),
			new Vec3(he.x, maxY, -he.z)
		];
		const faceAxes = [
			[0, 1, 3],
			// FRONT
			[4, 5, 7],
			// BACK
			[3, 2, 6],
			// TOP
			[1, 0, 4],
			// BOTTOM
			[1, 4, 2],
			// RIGHT
			[5, 0, 6]
			// LEFT
		];
		const faceNormals = [
			[0, 0, 1],
			// FRONT
			[0, 0, -1],
			// BACK
			[0, 1, 0],
			// TOP
			[0, -1, 0],
			// BOTTOM
			[1, 0, 0],
			// RIGHT
			[-1, 0, 0]
			// LEFT
		];
		const sides = {
			FRONT: 0,
			BACK: 1,
			TOP: 2,
			BOTTOM: 3,
			RIGHT: 4,
			LEFT: 5
		};
		const positions = [];
		const normals = [];
		const uvs = [];
		const uvs1 = [];
		const indices = [];
		let vcounter = 0;
		const generateFace = (side, uSegments, vSegments) => {
			const temp1 = new Vec3();
			const temp2 = new Vec3();
			const temp3 = new Vec3();
			const r = new Vec3();
			for (let i = 0; i <= uSegments; i++) {
				for (let j = 0; j <= vSegments; j++) {
					temp1.lerp(corners[faceAxes[side][0]], corners[faceAxes[side][1]], i / uSegments);
					temp2.lerp(corners[faceAxes[side][0]], corners[faceAxes[side][2]], j / vSegments);
					temp3.sub2(temp2, corners[faceAxes[side][0]]);
					r.add2(temp1, temp3);
					let u = i / uSegments;
					let v = j / vSegments;
					positions.push(r.x, r.y, r.z);
					normals.push(faceNormals[side][0], faceNormals[side][1], faceNormals[side][2]);
					uvs.push(u, 1 - v);
					u = u * primitiveUv1PaddingScale + primitiveUv1Padding;
					v = v * primitiveUv1PaddingScale + primitiveUv1Padding;
					u /= 3;
					v /= 3;
					u += side % 3 / 3;
					v += Math.floor(side / 3) / 3;
					uvs1.push(u, 1 - v);
					if (i < uSegments && j < vSegments) {
						indices.push(vcounter + vSegments + 1, vcounter + 1, vcounter);
						indices.push(vcounter + vSegments + 1, vcounter + vSegments + 2, vcounter + 1);
					}
					vcounter++;
				}
			}
		};
		generateFace(sides.FRONT, ws, hs);
		generateFace(sides.BACK, ws, hs);
		generateFace(sides.TOP, ws, ls);
		generateFace(sides.BOTTOM, ws, ls);
		generateFace(sides.RIGHT, ls, hs);
		generateFace(sides.LEFT, ls, hs);
		this.positions = positions;
		this.normals = normals;
		this.uvs = uvs;
		this.uvs1 = uvs1;
		this.indices = indices;
		if (opts.calculateTangents) {
			this.tangents = calculateTangents(positions, normals, uvs, indices);
		}
	}
}
export {
	BoxGeometry
};