【threejs】较大物体或shape的贴图较小问题处理方法

问题

有的场景内相对体型差距过大的物体（如山地海洋等····）由于尺寸问题，加载贴图过于小，同时shader也无法完全展示，如图

我们可以获取物体的uv，进行缩放使得贴图可以完全展开

如果uv是乱的可以用xyz坐标最大最小值先排布uv再对uv进行缩放

javascript 复制代码

//假设你有一个 mest.geometry(物体网格)
 		let max = { x: 10000, y: 10000, z: 10000 }
        let min = { x: 30000, y: 30000, z: 30000 }
        let positions = geometry.getAttribute('position').array.map((item, index) => {
            let axis = index % 3
            switch (axis) {
                case 0:
                    return item - min.x
                    break;
                case 1:
                    return item - min.y
                    break;
                case 2:
                    return item - min.z
                    break;
                default:
                    break;
            }
        })

        let uv_ = []
        let _X = max.x - min.x
        let _Y = max.y - min.y
        let _Z = max.z - min.z
        for (let i = 0; i < positions.length / 3; i++) {
            let x = positions[i * 3]
            let y = positions[i * 3 + 1]
            let z = positions[i * 3 + 2]
            let _u = x / _X
            let _v = z / _Z
            // 或者你的高度轴是y
            //  _v = y/_Y
            uv_.push(_u, _v)

        }
        let uvs = uv_.map(item=>item*scale)//缩放

        // 只是改原始模型uv比例 
        let uvs = geometry.getAttribute('uv').array.map(item => item / 500)//缩放uv

        // uv传给geometry（网格）
        geometry.setAttribute('uv', new Float32BufferAttribute(uvs, 2))
```

# 效果
```javascript
//我这里只是进行uv缩放
        const mesh = new Mesh(geometry, mat)
        // mesh.position.setZ(-this.lineTick)
        mesh.position.set(startX, startY, - this.lineTick)
        // console.log(geometry);
        let uvs = geometry.getAttribute('uv').array.map(item => item / 500)//缩放
        geometry.setAttribute('uv', new Float32BufferAttribute(uvs, 2))
        mesh.scale.set(scale, scale, 1)
        return mesh
```

![在这里插入图片描述](https://img-blog.csdnimg.cn/direct/d3ddd5998906476bb488d32da7fb56a9.png)
贴图完全展开了