build tag for vulkan uses go-vulkan's glfw3.3

and use sync.Once in exit so we don't close a closed channel

common/mouse.go

@@ -178,7 +178,7 @@ func (m *MouseSystem) Remove(basic ecs.BasicEntity) {
 func (m *MouseSystem) Update(dt float32) {
 	// Translate Mouse.X and Mouse.Y into "game coordinates"
 	switch engo.CurrentBackEnd {
-	case engo.BackEndGLFW, engo.BackEndSDL:
+	case engo.BackEndGLFW, engo.BackEndSDL, engo.BackEndVulkan:
 		m.mouseX = engo.Input.Mouse.X*m.camera.Z() + (m.camera.X()-(engo.GameWidth()/2)*m.camera.Z())/engo.GetGlobalScale().X
 		m.mouseY = engo.Input.Mouse.Y*m.camera.Z() + (m.camera.Y()-(engo.GameHeight()/2)*m.camera.Z())/engo.GetGlobalScale().Y
 	case engo.BackEndMobile:

engo.go

@@ -22,6 +22,8 @@ const (
 	BackEndSDL
 	// BackEndHeadless does not use a window manager for the backend
 	BackEndHeadless
+	// BackEndVulkan uses glfw 3.3 from vulkan-go and vulkan as a render surface
+	BackEndVulkan
 )
 
 var (
@@ -40,6 +42,7 @@ var (
 	opts                      RunOptions
 	resetLoopTicker           = make(chan bool, 1)
 	closeGame                 = make(chan struct{})
+	closeGameOnce             sync.Once
 	gameWidth, gameHeight     float32
 	windowWidth, windowHeight float32
 	canvasWidth, canvasHeight float32
@@ -262,7 +265,9 @@ func ScaleOnResize() bool {
 
 // Exit is the safest way to close your game, as `engo` will correctly attempt to close all windows, handlers and contexts
 func Exit() {
-	close(closeGame)
+	closeGameOnce.Do(func() {
+		close(closeGame)
+	})
 }
 
 // GameWidth returns the current game width

engo_glfw.go

@@ -1,5 +1,5 @@
 // +build darwin,!arm,!arm64 linux windows
-// +build !ios,!android,!netgo,!sdl,!headless
+// +build !ios,!android,!netgo,!sdl,!headless,!vulkan
 
 package engo
 
@@ -209,10 +209,9 @@ func CreateWindow(title string, width, height int, fullscreen bool, msaa int) {
 		// it's like KeyCallback, but for specific characters instead of keys...?
 		// responder.Type(char)
 	})
+
 	Window.SetCloseCallback(func(Window *glfw.Window) {
-		go func() {
-			closeGame <- struct{}{}
-		}()
+		Exit()
 	})
 }
 

engo_sdl.go

@@ -130,9 +130,7 @@ func RunIteration() {
 		for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
 			switch e := event.(type) {
 			case *sdl.QuitEvent:
-				go func() {
-					closeGame <- struct{}{}
-				}()
+				Exit()
 			case *sdl.KeyboardEvent:
 				key := Key(e.Keysym.Sym)
 				if e.GetType() == sdl.KEYUP {