import React , { createContext , useCallback , useContext , useEffect , useLayoutEffect , useRef , useState } from "react" ; import { InstancedMesh as TInstancedMesh , Matrix4 , Mesh , Object3D } from "three" ; import { useGLTF } from "@react-three/drei/core/useGLTF" ; import { useDidMount } from "../utils/hooks" ; type InstanceData = { position ? : [ number , number , number ] ; rotation ? : [ number , number , number ] ; scale ? : [ number , number , number ] ; } ; type UpdateInstanceFn = ( data : InstanceData ) => void ; type AddInstanceFn = ( data : InstanceData ) => [ UpdateInstanceFn , ( ) => void ] ; type InstancedMeshes = { [ key ] : AddInstanceFn ; } ; type ContextState = { instancedMeshes : InstancedMeshes ; createInstancedMesh : ( meshKey : string , addInstance : AddInstanceFn ) => ( ) => void ; } ; const Context = createContext ( null as unknown as ContextState ) ; export const useCreateInstancedMesh = ( ) => { return useContext ( Context ) . createInstancedMesh ; } ; export const useAddInstance = ( meshKey ) => { const instancedMeshes = useContext ( Context ) . instancedMeshes ; const addInstance = instancedMeshes [ meshKey ] ?? null ; return addInstance ; } ; export const useInstancedMesh = ( meshKey , data ) => { const updateRef = useRef < UpdateInstanceFn > ( ) ; const addInstance = useAddInstance ( meshKey ) ; useEffect ( ( ) => { if ( addInstance ) { const [ update , remove ] = addInstance ( data ) ; updateRef . current = update ; return remove ; } return ; } , [ addInstance , updateRef ] ) ; return useCallback ( ( data ) => { if ( updateRef . current ) { updateRef . current ( data ) ; } } , [ updateRef ] ) ; } ; export const Instance = ( { meshKey , ... data } ) => { const isMountRef = useRef ( true ) ; const update = useInstancedMesh ( meshKey , data ) ; const { position , rotation , scale } = data ; useEffect ( ( ) => { if ( isMountRef . current ) { isMountRef . current = false ; return ; } update ( { position , rotation , scale } ) ; } , [ position , rotation , scale , update ] ) ; return null ; } ; const defaultObject = new Object3D ( ) ; export const InstancedMesh = ( { meshKey , maxInstances , gltfPath , meshProps = { } } ) => { const createInstancedMesh = useCreateInstancedMesh ( ) ; const { nodes } = useGLTF ( gltfPath ) as unknown as { nodes : { [ key ] : Object3D ; } ; } ; const meshes = Object . values ( nodes ) . filter ( node => node . type === "Mesh" ) as Mesh [ ] ; const instancedMeshes = useRef < TInstancedMesh [ ] > ( [ ] ) ; const handleRef = useCallback ( ( instancedMesh ) => { instancedMeshes . current . push ( instancedMesh ) ; } , [ instancedMeshes ] ) ; useLayoutEffect ( ( ) => { instancedMeshes . current . forEach ( instancedMesh => { instancedMesh . count = 0 ; } ) ; } , [ instancedMeshes ] ) ; const idRef = useRef ( 0 ) ; const instancesRef = useRef < string [ ] > ( [ ] ) ; const removeInstance = useCallback ( ( id ) => { const instanceIndex = instancesRef . current . findIndex ( instanceId => instanceId === id ) ; instancedMeshes . current . forEach ( instancedMesh => { const count = instancedMesh . count ; for ( let i = instanceIndex + 1 ; i < count ; i ++ ) { const previousIndex = i - 1 ; if ( previousIndex < 0 ) break ; const matrix = new Matrix4 ( ) ; instancedMeshes . current . forEach ( instancedMesh => { instancedMesh . getMatrixAt ( i , matrix ) ; instancedMesh . setMatrixAt ( previousIndex , matrix ) ; } ) ; } } ) ; instancesRef . current . splice ( instanceIndex , 1 ) ; instancedMeshes . current . forEach ( instancedMesh => { instancedMesh . count = instancesRef . current . length ; } ) ; } , [ instancedMeshes , instancesRef ] ) ; const updateInstance = useCallback ( ( id , { position = [ 0 , 0 , 0 ] , rotation = [ 0 , 0 , 0 ] , scale = [ 1 , 1 , 1 ] } ) => { const instanceIndex = instancesRef . current . findIndex ( instanceId => instanceId === id ) ; defaultObject . position . set ( ... position ) ; defaultObject . rotation . set ( ... rotation ) ; defaultObject . scale . set ( ... scale ) ; defaultObject . updateMatrix ( ) ; instancedMeshes . current . forEach ( instancedMesh => { instancedMesh . setMatrixAt ( instanceIndex , defaultObject . matrix ) ; instancedMesh . instanceMatrix . needsUpdate = true ; } ) ; } , [ instancedMeshes , instancesRef ] ) ; const addInstance = useCallback ( ( data ) : [ UpdateInstanceFn , ( ) => void ] => { idRef . current += 1 ; const id = `${ idRef . current }` ; instancesRef . current . push ( id ) ; updateInstance ( id , data ) ; instancedMeshes . current . forEach ( instancedMesh => { instancedMesh . count = instancesRef . current . length ; } ) ; const update = ( updateData ) => { updateInstance ( id , updateData ) ; } ; const unsubscribe = ( ) => { removeInstance ( id ) ; } ; return [ update , unsubscribe ] ; } , [ instancedMeshes , idRef , updateInstance , removeInstance ] ) ; useEffect ( ( ) => { const unsubscribe = createInstancedMesh ( meshKey , addInstance ) ; return unsubscribe ; } , [ createInstancedMesh , addInstance ] ) ; return ( < > { meshes . map ( ( mesh ) => ( < instancedMesh ref = { handleRef } matrixAutoUpdate = { false } args = { [ mesh . geometry , mesh . material , maxInstances ] as any } key = { mesh . uuid } { ... meshProps } / > ) ) } < />); } ; export const InstancesProvider = ( { children } ) => { const [ instancedMeshes , setInstancedMeshes ] = useState < InstancedMeshes > ( { } ) ; const createInstancedMesh = useCallback ( ( meshKey , addInstance ) => { setInstancedMeshes ( state => { return { ... state , [ meshKey ] : addInstance } ; } ) ; const unsubscribe = ( ) => { setInstancedMeshes ( state => { const updatedState = { ... state } ; delete updatedState [ meshKey ] ; return updatedState ; } ) ; } ; return unsubscribe ; } , [ setInstancedMeshes ] ) ; return ( < Context . Provider value = { { instancedMeshes , createInstancedMesh } } > { children } < /Context.Provider>); } ;