版本：3.8.5

实现目标：给3d道路生成路边景观花草

在场景下创建一个节点，我这里种植两种花草模型，兰花和菊花，所以分别在节点下另创建两个节点，为了静态合批。

 1.将花草模型分别拖入场景中，制作成预制文件。

 2.给plant节点绑定一个脚本，用来初始化生成植物。

一般道路是由平面连接成，所以需要先获取道路模型的网格顶点

    /**
     * 根据 道路路径获取两侧边界点
     * @param roadPath 
     */
    public static getPointByRoad(roadPath: string) {
        try {
            let road = find(roadPath)
            let mesh = CommonUtil.getMeshRendererAdapter(road).mesh
            let pos = mesh.renderingSubMeshes[mesh.jointBufferIndices[0]].geometricInfo.positions;
            let result = []

            let worldMatrix = mat4();
            CommonUtil.getMeshRendererAdapter(road).node.getWorldMatrix(worldMatrix);

            for (let i = 0; i < pos.length; i += 3) {
                //顶点的本地坐标坐标转世界坐标
                let position=new Vec3()
                Vec3.fromArray(position, pos, i);
                let transform = v3();
                Vec3.transformMat4(transform, position, worldMatrix);
                result.push(transform)
            }
            return result
        } catch (e) {
            return []
        }
    }

如果模型面数比较大，数据就要进行抽稀

    public static dataDilution(data=[],deg:number=1){
        if(deg<=1||data.length==0){
            return data
        }
        let arr=[]
        for(let i=0;i<data.length;i+=deg){
            arr.push(data[i])
        }
        return arr
    }

现在就可以在plant脚本上进行创建使用了

    initData(){
        let arr = RoadsidePlantUtil.getPointByRoad(this.roadPath)
        arr = RoadsidePlantUtil.dataDilution(arr,2)
        let lanhuag=find(MarryManUtil.housPath + '/luduan/plant/lanhuag')
        let juhuag=find(MarryManUtil.housPath + '/luduan/plant/juhuag')
        for(let i=0;i<arr.length;i++){
            //y值小于-30不进行操作
            if(arr[i].y<-30){
                continue
            }
            let tty = Math.random() * 2
            if(tty<1){
                resources.load('prefab/flower/lanhua', Prefab, (err: any, data) => {
                    if (!data) {
                        return
                    }
                    let hua = instantiate(data)
                    hua.parent = lanhuag
                    hua.setPosition(v3(arr[i].x,arr[i].y,arr[i].z))
                })
            }else {
                resources.load('prefab/flower/juhua', Prefab, (err: any, data) => {
                    if (!data) {
                        return
                    }
                    let hua = instantiate(data)
                    hua.parent = juhuag
                    hua.setPosition(v3(arr[i].x,arr[i].y,arr[i].z))
                })
            }
        }
    }

效果如下