input: Use sync.Once

internal/input/input_glfw.go

@@ -30,7 +30,7 @@ import (
 type Input struct {
 	keyPressed         map[glfw.Key]bool
 	mouseButtonPressed map[glfw.MouseButton]bool
-	callbacksInitialized bool
+	onceCallback       sync.Once
 	scrollX            float64
 	scrollY            float64
 	cursorX            int
@@ -120,15 +120,14 @@ func (i *Input) Update(window *glfw.Window, scale float64) {
 	i.m.Lock()
 	defer i.m.Unlock()
 
-	if !i.callbacksInitialized {
+	i.onceCallback.Do(func() {
 		window.SetCharModsCallback(func(w *glfw.Window, char rune, mods glfw.ModifierKey) {
 			i.appendRuneBuffer(char)
 		})
 		window.SetScrollCallback(func(w *glfw.Window, xoff float64, yoff float64) {
 			i.setWheel(xoff, yoff)
 		})
-		i.callbacksInitialized = true
-	}
+	})
 	if i.keyPressed == nil {
 		i.keyPressed = map[glfw.Key]bool{}
 	}