Add support for running in headless mode

flags.go

@@ -23,8 +23,10 @@ func parseFlags() {
 	flag.StringVar(&hostAddress, "host", "", "start hosting a match against a remote opponent at the specified address:port")
 	flag.StringVar(&connectAddress, "connect", "", "connect to a match hosted by a remote opponent at the specified address:port")
 	flag.IntVar(&world.LocalPort, "local", 0, "set local port (this should be different from your opponent's local port)")
-	flag.BoolVar(&printDebug, "debug", false, "enable printing debug messages")
+	flag.IntVar(&world.Debug, "debug", 0, "debug level (0 - disabled, 1 - print fps and net stats, 2 - draw hitboxes)")
+	flag.BoolVar(&printDebug, "debug-ggpo", false, "print GGPO debug messages")
 	flag.IntVar(&world.TPS, "tps", world.DefaultTPS, "set ticks per second (this is not normally required)")
+	flag.BoolVar(&world.Headless, "headless", false, "run in headless mode (for debug purposes)")
 	flag.Parse()
 
 	if printDebug {

game/game.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 
 	"code.rocketnine.space/tslocum/boxbrawl/component"
 	"code.rocketnine.space/tslocum/boxbrawl/entity"
@@ -676,6 +677,23 @@ func (g *Game) Draw(screen *ebiten.Image) {
 	}
 }
 
+// RunHeadless runs the game without using the display. Game.Draw is never called.
+func (g *Game) RunHeadless() error {
+	var (
+		t   = time.NewTicker(time.Second / time.Duration(world.TPS))
+		err error
+	)
+	for {
+		select {
+		case <-t.C:
+			err = g.Update()
+			if err != nil {
+				return err
+			}
+		}
+	}
+}
+
 func (g *Game) Exit() {
 	os.Exit(0)
 }

main.go

@@ -20,15 +20,6 @@ func main() {
 
 	parseFlags()
 
-	ebiten.SetTPS(world.TPS)
-
-	ebiten.SetFullscreen(world.Fullscreen)
-	if world.DisableVsync {
-		ebiten.SetFPSMode(ebiten.FPSModeVsyncOffMaximum)
-	} else {
-		ebiten.SetFPSMode(ebiten.FPSModeVsyncOn)
-	}
-
 	g, err := game.NewGame()
 	if err != nil {
 		log.Fatal(err)
@@ -44,6 +35,23 @@ func main() {
 		g.Exit()
 	}()
 
+	// Run in headless mode.
+	if world.Headless {
+		err = g.RunHeadless()
+		if err != nil {
+			log.Fatal(err)
+		}
+		return
+	}
+
+	// Run normally.
+	ebiten.SetTPS(world.TPS)
+	ebiten.SetFullscreen(world.Fullscreen)
+	if world.DisableVsync {
+		ebiten.SetFPSMode(ebiten.FPSModeVsyncOffMaximum)
+	} else {
+		ebiten.SetFPSMode(ebiten.FPSModeVsyncOn)
+	}
 	err = ebiten.RunGame(g)
 	if err != nil {
 		log.Fatal(err)

system/ui.go

@@ -17,8 +17,8 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
 
-const uiStartPrompt = `Box Brawl
-`
+const uiStartPrompt = `BOX BRAWL`
+const uiBrowserIntro = `Click anywhere to enable keyboard input.`
 const uiComputerPrompt = `Press <Enter> to play against the computer.`
 const uiHostPrompt = `Press <H> to host a match against a remote player.`
 const uiHostInfoPrompt = `Type your opponent's IP address and port (address:port) to host a match.`
@@ -66,6 +66,7 @@ func (u *UISystem) updateBuffer() {
 	prompt := []byte(uiStartPrompt)
 
 	if world.WASM {
+		prompt = append(prompt, []byte("\n\n"+uiBrowserIntro)...)
 		prompt = append(prompt, []byte("\n\n"+uiComputerPrompt)...)
 		prompt = append(prompt, []byte("\n\n"+uiBrowserPrompt)...)
 	} else if world.ConnectionActive {
@@ -313,8 +314,10 @@ func (u *UISystem) Draw(e gohan.Entity, screen *ebiten.Image) error {
 	}
 
 	if world.Debug != 0 {
-		var ping int64
-		var framesBehind float64
+		var (
+			ping         int64
+			framesBehind float64
+		)
 		if !world.ConnectPromptVisible && !world.Local {
 			p1Stats, err := world.Backend.GetNetworkStats(ggpo.PlayerHandle(1))
 			if err != nil {
@@ -333,18 +336,26 @@ func (u *UISystem) Draw(e gohan.Entity, screen *ebiten.Image) error {
 			ping = yourStats.Network.Ping
 			framesBehind = math.Round(float64(yourStats.Timesync.LocalFramesBehind))
 		}
-
 		framesLabel := "AHEAD"
 		if framesBehind > 0 {
 			framesLabel = "BEHIND"
 		}
 
+		var (
+			tps float64
+			fps float64
+		)
+		if !world.Headless {
+			tps = ebiten.ActualTPS()
+			fps = ebiten.ActualFPS()
+		}
+
 		debugText := fmt.Sprintf("FRAMES %s %.0f\nPING %d\nTPS %0.0f\nFPS %0.0f",
 			framesLabel,
 			math.Abs(framesBehind),
 			ping,
-			ebiten.ActualTPS(),
-			ebiten.ActualFPS())
+			tps,
+			fps)
 		ebitenutil.DebugPrintAt(screen, debugText, 2, 0)
 	}
 	return nil

world/world.go

@@ -41,6 +41,7 @@ var (
 
 	Fullscreen   bool
 	DisableVsync bool
+	Headless     bool // Run without using the display
 
 	ScreenWidth, ScreenHeight = 0, 0
 
@@ -54,7 +55,7 @@ var (
 	ConnectPromptConfirmed bool
 	ConnectionActive       bool
 
-	Debug = 1 // TODO
+	Debug int
 
 	WASM bool