send/receive frame deltas

internal/app/ui.go

@@ -156,6 +156,22 @@ func (ui *UI) handleNotification(v wire.Value) bool {
 		ui.room.Entities = n.Entities
 		return true
 
+	case *wire.Delta:
+		if n.RoomSize != nil {
+			ui.room.Rect = *n.RoomSize
+		}
+
+		if len(n.Entities) > 0 {
+			for id, e := range n.Entities {
+				if e != nil {
+					ui.room.Entities[id] = *e
+				} else {
+					delete(ui.room.Entities, id)
+				}
+			}
+		}
+		return true
+
 	case *sim.ChatMessage:
 		ui.chatView.history = append(ui.chatView.history, *n)
 		return true

internal/sim/world.go

@@ -291,7 +291,13 @@ func (w *world) tick(d time.Duration) {
 		r.lastFrame = frame
 
 		for _, p := range r.players {
+			switch {
+			case p.fullSync:
 				p.send(wire.Response{Body: frame})
+				p.fullSync = false
+			case delta != nil:
+				p.send(wire.Response{Body: delta})
+			}
 		}
 	}
 }

internal/wire/frame.go

@@ -155,4 +155,5 @@ func (d Delta) IsEmpty() bool {
 
 func init() {
 	Register(func() Value { return new(Frame) })
+	Register(func() Value { return new(Delta) })
 }