Fixed multi-barrier collision handling in backend.

README.md

@@ -1,11 +1,25 @@
 # Preface 
 
-This project is a demo for a websocket-based input synchronization method inspired by [GGPO](https://www.ggpo.net/).   
-![screenshot-1](./screenshot-1.png)
+This project is a demo for a websocket-based input synchronization method inspired by [GGPO](https://www.ggpo.net/).
 
-Please checkout [this demo video](https://pan.baidu.com/s/1aM6e8IWaJszFCYAsRjt19g?pwd=z02c) to see whether the source codes are doing what you expect for synchronization.
+_(how input delay roughly works)_
 
-The video mainly shows the following feature (yet I'm not surprised if they're not obvious): when a player didn't have its input arrived at the backend in time (e.g. due to local lag, network delay or reconnection), backend forces confirmation of a prediction of its own and sends the confirmed input together w/ a reference render frame to that player.
+![input_delay_intro](./charts/InputDelayIntro.jpg)
+
+_(how rollback-and-chase in this project roughly works)_
+
+![rollback_and_chase_intro](./charts/RollbackAndChase.jpg)
+
+_(in game screenshot)_
+
+![screenshot-1](./charts/screenshot-1.png)
+
+Please checkout [this demo video](https://pan.baidu.com/s/123LlWcT9X-wbcYybqYnvmA?pwd=qrlw) to see whether the source codes are doing what you expect for synchronization.
+
+The video mainly shows the following features.
+- The backend receives inputs from frontend peers and [by a GGPO-alike manner](https://github.com/pond3r/ggpo/blob/master/doc/README.md) broadcasts back for synchronization.
+- The game is recovered for a player upon reconnection.
+- Both backend(Golang) and frontend(JavaScript) execute collision detection and handle collision contacts by the same algorithm. The backend dynamics can be toggled off by [Room.BackendDynamicsEnabled](https://github.com/genxium/DelayNoMore/blob/v0.5.2/battle_srv/models/room.go#L813), but **when turned off the game couldn't support recovery upon reconnection**.
 
 # 1. Building & running
 
@@ -19,7 +33,7 @@ The video mainly shows the following feature (yet I'm not surprised if they're n
 - [protobuf CLI](https://developers.google.com/protocol-buffers/docs/downloads) (optional, only for development)
 
 ### Frontend
-- [CocosCreator v2.2.1](https://www.cocos.com/en/cocos-creator-2-2-1-released-with-performance-improvements) (mandatory, **ONLY AVAILABLE on Windows or OSX and should be exactly this version**, DON'T use any other version because CocosCreator is well-known for new versions not being backward incompatible)
+- [CocosCreator v2.2.1](https://www.cocos.com/en/cocos-creator-2-2-1-released-with-performance-improvements) (mandatory, **ONLY AVAILABLE on Windows or OSX and should be exactly this version**, DON'T use any other version because CocosCreator is well-known for new versions not being backward compatible)
 - [protojs](https://www.npmjs.com/package/protojs) (optional, only for development)
 
 ## 1.2 Provisioning
@@ -64,7 +78,7 @@ The easy way is to try out 2 players with test accounts on a same machine.
 - Open one browser instance, visit _http://localhost:7456?expectedRoomId=1_, input `add`on the username box and click to request a captcha, this is a test account so a captcha would be returned by the backend and filled automatically (as shown in the figure below), then click and click to proceed to a matching scene.
 - Open another browser instance, visit _http://localhost:7456?expectedRoomId=1_, input `bdd`on the username box and click to request a captcha, this is another test account so a captcha would be returned by the backend and filled automatically, then click and click to proceed, when matched a `battle`(but no competition rule yet) would start.
 - Try out the onscreen virtual joysticks to move the cars and see if their movements are in-sync.
-![screenshot-2](./screenshot-2.png)
+![screenshot-2](./charts/screenshot-2.png)
 
 ## 2 Troubleshooting
 

battle_srv/models/room.go

@@ -2,12 +2,17 @@ package models
 
 import (
 	. "dnmshared"
+	"encoding/xml"
 	"fmt"
 	"github.com/golang/protobuf/proto"
 	"github.com/gorilla/websocket"
 	"github.com/solarlune/resolv"
 	"go.uber.org/zap"
+	"io/ioutil"
+	"math"
 	"math/rand"
+	"os"
+	"path/filepath"
 	. "server/common"
 	"server/common/utils"
 	pb "server/pb_output"
@@ -15,11 +20,6 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
-
-	"encoding/xml"
-	"io/ioutil"
-	"os"
-	"path/filepath"
 )
 
 const (
@@ -459,9 +459,9 @@ func (pR *Room) StartBattle() {
 				pR.prefabInputFrameDownsync(noDelayInputFrameId)
 			}
 
-			// Force setting all-confirmed of buffered inputFrames periodically
 			unconfirmedMask := uint64(0)
 			if pR.BackendDynamicsEnabled {
+				// Force setting all-confirmed of buffered inputFrames periodically
 				unconfirmedMask = pR.forceConfirmationIfApplicable()
 			} else {
 				pR.markConfirmationIfApplicable()
@@ -474,7 +474,7 @@ func (pR *Room) StartBattle() {
 
 			   If "NstDelayFrames" becomes larger, "pR.RenderFrameId - refRenderFrameId" possibly becomes larger because the force confirmation is delayed more.
 
-			   Hence even upon resync, it's still possible that "refRenderFrameId < frontend.chaserRenderFrameId".
+			   Upon resync, it's still possible that "refRenderFrameId < frontend.chaserRenderFrameId" -- and this is allowed.
 			*/
 			refRenderFrameId := pR.ConvertToGeneratingRenderFrameId(upperToSendInputFrameId) + (1 << pR.InputScaleFrames) - 1
 			if refRenderFrameId > pR.RenderFrameId {
@@ -539,7 +539,7 @@ func (pR *Room) StartBattle() {
 						// [WARNING] When sending DOWNSYNC_MSG_ACT_FORCED_RESYNC, there MUST BE accompanying "toSendInputFrames" for calculating "refRenderFrameId"!
 
 						if MAGIC_LAST_SENT_INPUT_FRAME_ID_READDED == player.LastSentInputFrameId {
-							Logger.Warn(fmt.Sprintf("Not sending due to empty toSendInputFrames: roomId=%v, playerId=%v, refRenderFrameId=%v, candidateToSendInputFrameId=%v, upperToSendInputFrameId=%v, lastSentInputFrameId=%v, playerAckingInputFrameId=%v", pR.Id, playerId, refRenderFrameId, candidateToSendInputFrameId, upperToSendInputFrameId, player.LastSentInputFrameId, player.AckingInputFrameId))
+							Logger.Warn(fmt.Sprintf("Not sending due to empty toSendInputFrames: roomId=%v, playerId=%v, refRenderFrameId=%v, upperToSendInputFrameId=%v, lastSentInputFrameId=%v, playerAckingInputFrameId=%v", pR.Id, playerId, refRenderFrameId, upperToSendInputFrameId, player.LastSentInputFrameId, player.AckingInputFrameId))
 						}
 						continue
 					}
@@ -567,6 +567,17 @@ func (pR *Room) StartBattle() {
 			}
 
 			toApplyInputFrameId := pR.ConvertToInputFrameId(refRenderFrameId, pR.InputDelayFrames)
+			if false == pR.BackendDynamicsEnabled {
+				// When "false == pR.BackendDynamicsEnabled", the variable "refRenderFrameId" is not well defined
+				minLastSentInputFrameId := int32(math.MaxInt32)
+				for _, player := range pR.Players {
+					if player.LastSentInputFrameId >= minLastSentInputFrameId {
+						continue
+					}
+					minLastSentInputFrameId = player.LastSentInputFrameId
+				}
+				toApplyInputFrameId = minLastSentInputFrameId
+			}
 			for pR.InputsBuffer.N < pR.InputsBuffer.Cnt || (0 < pR.InputsBuffer.Cnt && pR.InputsBuffer.StFrameId < toApplyInputFrameId) {
 				f := pR.InputsBuffer.Pop().(*pb.InputFrameDownsync)
 				if pR.inputFrameIdDebuggable(f.InputFrameId) {
@@ -1205,14 +1216,16 @@ func (pR *Room) applyInputFrameDownsyncDynamics(fromRenderFrameId int32, toRende
 				playerCollider := pR.CollisionSysMap[collisionPlayerIndex]
 				if collision := playerCollider.Check(oldDx, oldDy, "Barrier"); collision != nil {
 					playerShape := playerCollider.Shape.(*resolv.ConvexPolygon)
-					barrierShape := collision.Objects[0].Shape.(*resolv.ConvexPolygon)
-					if overlapped, pushbackX, pushbackY := CalcPushbacks(oldDx, oldDy, playerShape, barrierShape); overlapped {
-						Logger.Debug(fmt.Sprintf("Collided & overlapped: player.X=%v, player.Y=%v, oldDx=%v, oldDy=%v, playerShape=%v, toCheckBarrier=%v, pushbackX=%v, pushbackY=%v", playerCollider.X, playerCollider.Y, oldDx, oldDy, ConvexPolygonStr(playerShape), ConvexPolygonStr(barrierShape), pushbackX, pushbackY))
-						dx -= pushbackX
-						dy -= pushbackY
-					} else {
-						Logger.Debug(fmt.Sprintf("Collider BUT not overlapped: player.X=%v, player.Y=%v, oldDx=%v, oldDy=%v, playerShape=%v, toCheckBarrier=%v", playerCollider.X, playerCollider.Y, oldDx, oldDy, ConvexPolygonStr(playerShape), ConvexPolygonStr(barrierShape)))
-					}
+                    for _, obj := range collision.Objects {
+                        barrierShape := obj.Shape.(*resolv.ConvexPolygon)
+                        if overlapped, pushbackX, pushbackY := CalcPushbacks(oldDx, oldDy, playerShape, barrierShape); overlapped {
+                            Logger.Debug(fmt.Sprintf("Collided & overlapped: player.X=%v, player.Y=%v, oldDx=%v, oldDy=%v, playerShape=%v, toCheckBarrier=%v, pushbackX=%v, pushbackY=%v", playerCollider.X, playerCollider.Y, oldDx, oldDy, ConvexPolygonStr(playerShape), ConvexPolygonStr(barrierShape), pushbackX, pushbackY))
+                            dx -= pushbackX
+                            dy -= pushbackY
+                        } else {
+                            Logger.Debug(fmt.Sprintf("Collided BUT not overlapped: player.X=%v, player.Y=%v, oldDx=%v, oldDy=%v, playerShape=%v, toCheckBarrier=%v", playerCollider.X, playerCollider.Y, oldDx, oldDy, ConvexPolygonStr(playerShape), ConvexPolygonStr(barrierShape)))
+                        }
+                    } 
 				}
 				playerCollider.X += dx
 				playerCollider.Y += dy

frontend/assets/scenes/login.fire

@@ -440,7 +440,7 @@
       "array": [
         0,
         0,
-        344.75930058781137,
+        209.73151519075364,
         0,
         0,
         0,