func (e *Engine) moveEntities(t message.AbsoluteTick) {
for _, ent := range e.entity.List() {
req, collidesWith := e.mover.UpdateEntity(ent, t)
// [GAME-SPECIFIC] Destroy balls when they collide
if collidesWith != nil && ent.Type == game.BallEntity {
req := entity.NewDeleteRequest(t, ent.Id)
if err := e.entity.AcceptRequest(req); err != nil {
panic(err) // This shouldn't happen
}
// If the ball collides with a player, decrease his health
if collidesWith, ok := collidesWith.(*message.Entity); ok && collidesWith.Type == game.PlayerEntity {
sender := ent.Attributes[game.SenderAttr].(message.EntityId)
if sender != collidesWith.Id {
health := collidesWith.Attributes[game.HealthAttr].(game.Health)
updated := entity.New()
updated.Attributes[game.HealthAttr] = health - 1
diff := message.NewEntityDiff()
diff.Attributes = true
req := entity.NewUpdateRequest(t, updated, diff)
if err := e.entity.AcceptRequest(req); err != nil {
panic(err) // This shouldn't happen
}
}
}
continue
}
if req != nil {
// Let's assume mover already did all security checks
if err := e.entity.AcceptRequest(req); err != nil {
// This should not fail
panic(err)
}
}
}
}
func (e *Engine) executeTick(currentTick message.AbsoluteTick) {
entityFrontend := e.entity.Frontend()
actionFrontend := e.action.Frontend()
// Process requests from clients
minTick := currentTick - message.MaxRewind
if message.MaxRewind > currentTick {
minTick = 0
}
acceptedMinTick := currentTick
accepted := list.New()
for {
var req message.Request
// Get last request
noMore := false
select {
case req = <-entityFrontend.Creates:
case req = <-entityFrontend.Updates:
case req = <-entityFrontend.Deletes:
case req = <-actionFrontend.Executes:
default:
noMore = true
}
if noMore {
break
}
t := req.GetTick()
if t == message.InvalidTick {
req.Done(errors.New("Invalid tick"))
log.Println("Warning: Dropped request, invalid tick")
continue
}
if t < minTick {
req.Done(errors.New("Request is too old"))
log.Println("Warning: Dropped request, too old", currentTick-t)
continue
}
if t > currentTick {
req.Done(errors.New("Request is in the future"))
log.Println("Warning: Dropped request, in the future", currentTick-t)
continue
}
if t < acceptedMinTick {
acceptedMinTick = t
}
// Append request to the list, keeping it ordered
inserted := false
for e := accepted.Front(); e != nil; e = e.Next() {
r := e.Value.(message.Request)
if r.GetTick() > req.GetTick() {
accepted.InsertBefore(req, e)
inserted = true
break
}
}
if !inserted {
accepted.PushBack(req)
}
}
if accepted.Len() > 0 {
//log.Println("Accepted", accepted.Len(), "requests from clients")
}
// Initiate lag compensation if necessary
if acceptedMinTick < currentTick {
log.Println("Back to the past!", currentTick, acceptedMinTick)
e.terrain.Rewind(e.terrain.GetTick() - acceptedMinTick)
e.entity.Rewind(e.entity.GetTick() - acceptedMinTick)
}
// Redo all deltas until now
entDeltas := e.entity.Deltas()
trnDeltas := e.terrain.Deltas()
entEl := entDeltas.FirstAfter(acceptedMinTick)
trnEl := trnDeltas.FirstAfter(acceptedMinTick)
var ed *entity.Delta
var td *terrain.Delta
for entEl != nil || trnEl != nil {
if entEl != nil {
ed = entEl.Value.(*entity.Delta)
} else {
ed = nil
}
if trnEl != nil {
td = trnEl.Value.(*terrain.Delta)
} else {
td = nil
}
// TODO: replace terain history by actions history
if ed == nil || (td != nil && ed.GetTick() >= td.GetTick()) {
// Process terrain delta
trnEl = trnEl.Next()
// Compute new entities positions just before the terrain change
e.moveEntities(td.GetTick() - 1)
// Redo terrain change
e.terrain.Redo(td)
}
if td == nil || (ed != nil && ed.GetTick() <= td.GetTick()) {
// Process entity delta
// Do not redo deltas not triggered by the user
// These are the ones that will be computed again
if !ed.Requested() {
entDeltas.Remove(entEl)
entEl = entEl.Next()
continue
}
entEl = entEl.Next()
// Compute new entities positions
e.moveEntities(ed.GetTick())
// Accept new requests at the correct tick
for el := accepted.Front(); el != nil; el = el.Next() {
req := el.Value.(message.Request)
if req.GetTick() >= ed.GetTick() {
break
}
e.processRequest(req)
accepted.Remove(el)
}
e.processRequest(ed.Request())
}
}
// Accept requests whose tick is > last delta tick
for el := accepted.Front(); el != nil; el = el.Next() {
req := el.Value.(entity.Request)
e.moveEntities(req.GetTick())
e.processRequest(req)
}
// Compute new entities positions
e.moveEntities(currentTick)
// Destroy entities that are not alive anymore
// TODO: history support
for _, ent := range e.entity.List() {
if val, ok := ent.Attributes[game.TicksLeftAttr]; ok {
ttl := val.(game.TicksLeft)
if ttl == 0 { // Destroy entity
err := e.entity.AcceptRequest(entity.NewDeleteRequest(currentTick, ent.Id))
if err != nil {
// This shouldn't fail
panic(err)
}
} else {
ent.Attributes[game.TicksLeftAttr] = ttl - 1
}
}
}
// Cleanup
e.entity.Cleanup(currentTick)
e.action.Cleanup(currentTick)
// DEBUG: print all entites
log.Printf("Tick %v finished, entities:\n", currentTick)
for _, ent := range e.entity.List() {
log.Printf("entity=%+v position=%+v speed=%+v", ent, ent.Position, ent.Speed)
}
}