Three.js：无法显示使用纹理数组创建的网格

Question

我正在基于你放置在沙盒世界中的立方体构建一个非常原始的游戏（一个完全独特的概念，它将彻底改变我们所知道的游戏）并且我正在处理块生成。 这是我到目前为止所拥有的：

我的块在 object 文字中定义：

import * as THREE from 'three';

const loader = new THREE.TextureLoader();

interface BlockAttrs
{
    breakable: boolean;
    empty:     boolean;
}

export interface Block
{
    attrs:       BlockAttrs;
    mat_bottom?: THREE.MeshBasicMaterial;
    mat_side?:   THREE.MeshBasicMaterial;
    mat_top?:    THREE.MeshBasicMaterial;
}

interface BlockList
{
    [key: string]: Block;
}

export const Blocks: BlockList = {
    air:
    {
        attrs:
        {
            breakable: false,
            empty: true,
        },
    },
    grass:
    {
        attrs:
        {
            breakable: true,
            empty: false,
        },
        mat_bottom: new THREE.MeshBasicMaterial({map: loader.load("/tex/dirt.png")}),
        mat_side: new THREE.MeshBasicMaterial({map: loader.load("/tex/grass-side.png")}),
        mat_top: new THREE.MeshBasicMaterial({map: loader.load("/tex/grass-top.png")}),
    },
};

这是我的Chunk class：

import * as THREE from 'three';
import { BufferGeometryUtils } from 'three/examples/jsm/utils/BufferGeometryUtils';

import { Block, Blocks } from './blocks';

const px = 0; const nx = 1; const py = 2;
const ny = 3; const pz = 4; const nz = 5;

export default class Chunk
{
    private static readonly faces = [
        new THREE.PlaneGeometry(1,1)
            .rotateY(Math.PI / 2)
            .translate(0.5, 0, 0),

        new THREE.PlaneGeometry(1,1)
            .rotateY(-Math.PI / 2)
            .translate(-0.5, 0, 0),

        new THREE.PlaneGeometry(1,1)
            .rotateX(-Math.PI / 2)
            .translate(0, 0.5, 0),

        new THREE.PlaneGeometry(1,1)
            .rotateX(Math.PI / 2)
            .translate(0, -0.5, 0),

        new THREE.PlaneGeometry(1,1)
            .translate(0, 0, 0.5),

        new THREE.PlaneGeometry(1,1)
            .rotateY(Math.PI)
            .translate(0, 0, -0.5)
    ];
    private structure: Array<Array<Array<Block>>>;
    public static readonly size = 16;
    private materials = Array<THREE.MeshBasicMaterial>();
    private terrain = Array<THREE.BufferGeometry>();

    constructor ()
    {
        this.structure = new Array<Array<Array<Block>>>(Chunk.size);

        for (let x = 0; x < Chunk.size; x++)
        {
            this.structure[x] = new Array<Array<Block>>(Chunk.size);

            for (let y = 0; y < Chunk.size; y++)
            {
                this.structure[x][y] = new Array<Block>(Chunk.size);

                for (let z = 0; z < Chunk.size; z++)
                    if ((x+y+z) % 2)
                        this.structure[x][y][z] = Blocks.grass;
                    else
                        this.structure[x][y][z] = Blocks.air;
            }
        }
    }

    private blockEmpty (x: number, y: number, z: number): boolean
    {
        let empty = true;

        if (
            x >= 0 && x < Chunk.size &&
            y >= 0 && y < Chunk.size &&
            z >= 0 && z < Chunk.size
        ) {
            empty = this.structure[x][y][z].attrs.empty;
        }

        return empty;
    }

    private generateBlockFaces (x: number, y: number, z: number): void
    {
        if (this.blockEmpty(x+1, y, z))
        {
            this.terrain.push(Chunk.faces[px].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_side);
        }

        if (this.blockEmpty(x, y, z+1))
        {
            this.terrain.push(Chunk.faces[nx].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_side);
        }

        if (this.blockEmpty(x, y-1, z))
        {
            this.terrain.push(Chunk.faces[py].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_bottom);
        }

        if (this.blockEmpty(x, y+1, z))
        {
            this.terrain.push(Chunk.faces[ny].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_top);
        }

        if (this.blockEmpty(x, y, z-1))
        {
            this.terrain.push(Chunk.faces[pz].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_side);
        }

        if (this.blockEmpty(x-1, y, z))
        {
            this.terrain.push(Chunk.faces[nz].clone().translate(x, y, z));
            this.materials.push(this.structure[x][y][z].mat_side);
        }
    }

    public generateTerrain (): THREE.Mesh
    {
        this.terrain   = new Array<THREE.BufferGeometry>();
        this.materials = new Array<THREE.MeshBasicMaterial>();

        for (let x = 0; x < Chunk.size; x++)
            for (let y = 0; y < Chunk.size; y++)
                for (let z = 0; z < Chunk.size; z++)
                    if (!this.structure[x][y][z].attrs.empty)
                        this.generateBlockFaces(x, y, z);

        return new THREE.Mesh(
            BufferGeometryUtils.mergeBufferGeometries(this.terrain),
            this.materials
        );
    }
}

我知道网格创建器应该与 model 分离，但现在我正在试验。 class 的工作原理如下：

首先， constructor()创建一个Block的 3D 矩阵。 我已将其设置为以air和grass的棋盘图案创建它，因此其他所有方块都是空的。

接下来，我从场景中调用generateTerrain() ：

this.chunk = new Chunk();
this.add(this.chunk.generateTerrain());

调用此方法时，它会为每个非空块进入generateBlockFaces ，并将适当的PlaneGeometry s 推送到terrain数组中，并将适当的THREE.MeshBasicMaterial送到materials数组中。 然后我使用BufferGeometryUtils.mergeBufferGeometries合并几何，并创建通过合并几何和materials数组的网格。

我遇到的问题是，在传递new THREE.MeshNormalMaterial或任何其他材料时创建网格效果很好，但当我传递materials数组时却不行。 传递数组会创建 object （和console.log显示它创建时没有错误），但它不是用场景绘制的。

我是否误以为materials数组将为每个面分配材质？ 我究竟做错了什么？

Answer 1

在文档中找到对THREE.UVMapping的引用后，我解决了它。 将几何图形发送到 GPU 时，纹理坐标需要是顶点坐标的双向。 为此，我在我的块中定义了以下三个属性：

uv_bottom: [
    stone_row     / Textures.rows, (stone_col+1) / Textures.cols,
    (stone_row+1) / Textures.rows, (stone_col+1) / Textures.cols,
    stone_row     / Textures.rows, stone_col     / Textures.cols,
    (stone_row+1) / Textures.rows, stone_col     / Textures.cols,
],
uv_side: [
    stone_row     / Textures.rows, (stone_col+1) / Textures.cols,
    (stone_row+1) / Textures.rows, (stone_col+1) / Textures.cols,
    stone_row     / Textures.rows, stone_col     / Textures.cols,
    (stone_row+1) / Textures.rows, stone_col     / Textures.cols,
],
uv_top: [
    stone_row     / Textures.rows, (stone_col+1) / Textures.cols,
    (stone_row+1) / Textures.rows, (stone_col+1) / Textures.cols,
    stone_row     / Textures.rows, stone_col     / Textures.cols,
    (stone_row+1) / Textures.rows, stone_col     / Textures.cols,
],

Textures.rows和Textures.cols引用了我的纹理图集（所有纹理都存储在 png 网格中的文件）具有的列数和行数，并且每个块都有自己的row和col文件，引用其 position。 然后，我创建了一个private uv = Array<Array<number>>(); 在我的Chunk class 中并修改地形生成器以将块的 uv arrays 推到它。 例如，这是对正z面的处理方式（请注意，为了提高效率，我交换了y和z ）：

if (this.blockEmpty(x, z+1, y))
{
    this.terrain.push(Chunk.faces[pz].clone().translate(x, y, z));
    this.uv.push(this.structure[x][z][y].uv_side);
}

现在， BufferGeometry只接受'uv' arrays 作为类型（在本例中为Float32Array ），所以我必须从this.uv的扁平版本构造一个。 这就是地形生成器 function 现在的样子：

public generateTerrain (): THREE.Mesh
{
    this.terrain = new Array<THREE.BufferGeometry>();

    for (let x = 0; x < Chunk.base; x++)
        for (let z = 0; z < Chunk.base; z++)
            for (let y = 0; y < Chunk.build_height; y++)
                if (!this.structure[x][z][y].attrs.empty)
                    this.generateBlockFaces(x, z, y);

    const geometry = BufferGeometryUtils.mergeBufferGeometries(this.terrain);
    geometry.setAttribute('uv', new THREE.BufferAttribute(new Float32Array(this.uv.flat()), 2));

    return new THREE.Mesh(geometry, Textures.material);
}

如您所见，我使用的材质来自Textures class。 这是整个导入的文件：

import * as THREE from 'three';

export default class Textures
{
    private static readonly loader = new THREE.TextureLoader();

    public static readonly rows = 3;
    public static readonly cols = 2;

    public static readonly atlas    = Textures.loader.load("/tex/atlas.png");
    public static readonly material = new THREE.MeshBasicMaterial({map: Textures.atlas});
}

Textures.atlas.magFilter = THREE.NearestFilter;
Textures.atlas.minFilter = THREE.NearestFilter;

就是这样：地形现在生成渲染每个块的纹理，我对此非常高兴：D

Answer 2

对于想要使用材质数组的人：

const materials = [
  new THREE.MeshBasicMaterial( { color: 'red' } ),
  new THREE.MeshBasicMaterial( { color: 'blue' } )
];

const geometries = [
  new THREE.PlaneGeometry( 1, 1 ),
  new THREE.PlaneGeometry( 1, 1 )
];
geometries[ 1 ].rotateX( Math.PI * -0.5 );

// Add groups that set the materialIndex of each vertex in a group
// For this code all the vertices in each geometry have the same material. 
// If you load in a model that already has multiple textures you don't need to do this.
geometries[ 0 ].addGroup( 0, geometries[0].attributes.position.count, 0 ); 
geometries[ 1 ].addGroup( 0, geometries[1].attributes.position.count, 1 );

// Setting true on the second argument enables groups for the merged geometry.
const mergedGeometry = BufferGeometryUtils.mergeBufferGeometries( geometries, true );

const multiMaterialMesh = new THREE.Mesh( mergedGeometry, materials );
scene.add( multiMaterialMesh );