Implement Gamepad API for JavaScript (working on Firefox so far)

example/gamepad/main.go

@@ -29,6 +29,7 @@ const (
 )
 
 func update(screen *ebiten.Image) error {
+	// TODO: API to get the available, lowest ID
 	const gamepadID = 0
 	axes := []string{}
 	pressedButtons := []string{}

internal/ui/input_glfw.go

@@ -37,33 +37,33 @@ func (i *input) update(window *glfw.Window, scale int) error {
 	x, y := window.GetCursorPosition()
 	i.cursorX = int(math.Floor(x)) / scale
 	i.cursorY = int(math.Floor(y)) / scale
-	for j := glfw.Joystick(0); j < glfw.Joystick(len(i.gamepads)); j++ {
-		if !glfw.JoystickPresent(j) {
+	for id := glfw.Joystick(0); id < glfw.Joystick(len(i.gamepads)); id++ {
+		if !glfw.JoystickPresent(id) {
 			continue
 		}
-		axes32, err := glfw.GetJoystickAxes(j)
+		axes32, err := glfw.GetJoystickAxes(id)
 		if err != nil {
 			return err
 		}
-		i.gamepads[j].axisNum = len(axes32)
-		for a := 0; a < len(i.gamepads[j].axes); a++ {
+		i.gamepads[id].axisNum = len(axes32)
+		for a := 0; a < len(i.gamepads[id].axes); a++ {
 			if len(axes32) <= a {
-				i.gamepads[j].axes[a] = 0
+				i.gamepads[id].axes[a] = 0
 				continue
 			}
-			i.gamepads[j].axes[a] = float64(axes32[a])
+			i.gamepads[id].axes[a] = float64(axes32[a])
 		}
-		buttons, err := glfw.GetJoystickButtons(j)
+		buttons, err := glfw.GetJoystickButtons(id)
 		if err != nil {
 			return err
 		}
-		i.gamepads[j].buttonNum = len(buttons)
-		for b := 0; b < len(i.gamepads[j].buttonPressed); b++ {
+		i.gamepads[id].buttonNum = len(buttons)
+		for b := 0; b < len(i.gamepads[id].buttonPressed); b++ {
 			if len(buttons) <= b {
-				i.gamepads[j].buttonPressed[b] = false
+				i.gamepads[id].buttonPressed[b] = false
 				continue
 			}
-			i.gamepads[j].buttonPressed[b] = glfw.Action(buttons[b]) == glfw.Press
+			i.gamepads[id].buttonPressed[b] = glfw.Action(buttons[b]) == glfw.Press
 		}
 	}
 	return nil

internal/ui/input_js.go

@@ -16,6 +16,10 @@
 
 package ui
 
+import (
+	"github.com/gopherjs/gopherjs/js"
+)
+
 func (i *input) keyDown(key int) {
 	k, ok := keyCodeToKey[key]
 	if !ok {
@@ -59,3 +63,36 @@ func (i *input) mouseUp(button int) {
 func (i *input) mouseMove(x, y int) {
 	i.cursorX, i.cursorY = x, y
 }
+
+func (i *input) updateGamepads() {
+	gamepads := js.Global.Get("navigator").Call("getGamepads")
+	l := gamepads.Get("length").Int()
+	for id := 0; id < l; id++ {
+		gamepad := gamepads.Index(id)
+		if gamepad == js.Undefined || gamepad == nil {
+			continue
+		}
+
+		axes := gamepad.Get("axes")
+		axesNum := axes.Get("length").Int()
+		i.gamepads[id].axisNum = axesNum
+		for a := 0; a < len(i.gamepads[id].axes); a++ {
+			if axesNum <= a {
+				i.gamepads[id].axes[a] = 0
+				continue
+			}
+			i.gamepads[id].axes[a] = axes.Index(a).Float()
+		}
+
+		buttons := gamepad.Get("buttons")
+		buttonsNum := buttons.Get("length").Int()
+		i.gamepads[id].buttonNum = buttonsNum
+		for b := 0; b < len(i.gamepads[id].buttonPressed); b++ {
+			if buttonsNum <= b {
+				i.gamepads[id].buttonPressed[b] = false
+				continue
+			}
+			i.gamepads[id].buttonPressed[b] = buttons.Index(b).Get("pressed").Bool()
+		}
+	}
+}

internal/ui/ui_js.go

@@ -47,6 +47,7 @@ func DoEvents() error {
 	for !shown() {
 		vsync()
 	}
+	currentInput.updateGamepads()
 	return nil
 }
 
@@ -66,9 +67,10 @@ func init() {
 	// TODO: Implement this with node-webgl mainly for testing.
 
 	doc := js.Global.Get("document")
+	window := js.Global.Get("window")
 	if doc.Get("body") == nil {
 		ch := make(chan struct{})
-		js.Global.Get("window").Call("addEventListener", "load", func() {
+		window.Call("addEventListener", "load", func() {
 			close(ch)
 		})
 		<-ch
@@ -127,6 +129,7 @@ func init() {
 	canvas.Call("setAttribute", "tabindex", 1)
 	canvas.Get("style").Set("outline", "none")
 
+	// Keyboard
 	canvas.Call("addEventListener", "keydown", func(e js.Object) bool {
 		code := e.Get("keyCode").Int()
 		currentInput.keyDown(code)
@@ -137,6 +140,8 @@ func init() {
 		currentInput.keyUp(code)
 		return false
 	})
+
+	// Mouse
 	canvas.Call("addEventListener", "mousedown", func(e js.Object) bool {
 		button := e.Get("button").Int()
 		currentInput.mouseDown(button)
@@ -150,6 +155,14 @@ func init() {
 	canvas.Call("addEventListener", "contextmenu", func(e js.Object) bool {
 		return false
 	})
+
+	// Gamepad
+	window.Call("addEventListener", "gamepadconnected", func(e js.Object) {
+		print(e)
+	})
+	window.Call("addEventListener", "gamepaddisconnected", func(e js.Object) {
+		print(e)
+	})
 }
 
 func devicePixelRatio() int {