Captured/uncaptured mode in input package+comments

engine/engine.go

@@ -33,25 +33,12 @@ type Window struct {
 
 func (w *Window) handleInputs() {
 
-	input.EventLoopStart()
 	imIo := imgui.CurrentIO()
 
 	imguiCaptureMouse := imIo.WantCaptureMouse()
 	imguiCaptureKeyboard := imIo.WantCaptureKeyboard()
 
-	// These two are to fix a bug where state isn't cleared
+	input.EventLoopStart(imguiCaptureMouse, imguiCaptureKeyboard)
-	// even after imgui captures the keyboard/mouse.
-	//
-	// For example, if player is moving due to key held and then imgui captures the keyboard,
-	// the player keeps moving even when the key is no longer pressed because the input system never
-	// receives the key up event.
-	if imguiCaptureMouse {
-		input.ClearMouseState()
-	}
-
-	if imguiCaptureKeyboard {
-		input.ClearKeyboardState()
-	}
 
 	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
 
@@ -65,18 +52,12 @@ func (w *Window) handleInputs() {
 
 		case *sdl.MouseWheelEvent:
 
-			if !imguiCaptureMouse {
+			input.HandleMouseWheelEvent(e)
-				input.HandleMouseWheelEvent(e)
-			}
-
 			imIo.AddMouseWheelDelta(float32(e.X), float32(e.Y))
 
 		case *sdl.KeyboardEvent:
 
-			if !imguiCaptureKeyboard {
+			input.HandleKeyboardEvent(e)
-				input.HandleKeyboardEvent(e)
-			}
-
 			imIo.AddKeyEvent(nmageimgui.SdlScancodeToImGuiKey(e.Keysym.Scancode), e.Type == sdl.KEYDOWN)
 
 			// Send modifier key updates to imgui
@@ -101,10 +82,7 @@ func (w *Window) handleInputs() {
 
 		case *sdl.MouseButtonEvent:
 
-			if !imguiCaptureMouse {
+			input.HandleMouseBtnEvent(e)
-				input.HandleMouseBtnEvent(e)
-			}
-
 			isPressed := e.State == sdl.PRESSED
 
 			if e.Button == sdl.BUTTON_LEFT {
@@ -117,9 +95,7 @@ func (w *Window) handleInputs() {
 
 		case *sdl.MouseMotionEvent:
 
-			if !imguiCaptureMouse {
+			input.HandleMouseMotionEvent(e)
-				input.HandleMouseMotionEvent(e)
-			}
 
 		case *sdl.WindowEvent:
 

input/input.go

@@ -1,6 +1,23 @@
+// The input package provides an interface to mouse and keyboard inputs
+// like key clicks and releases, along with some higher level constructs like
+// pressed/released this frames, double clicks, and normalized inputs.
+//
+// The input package has two sets of functions for most cases, where one
+// is in the form 'xy' and the other 'xyCaptured'. The captured form
+// always returns normal events even if the mouse or keyboard are captured
+// by the UI system. The 'xy' form however will return zero/false if the
+// respective input device is currently captured (with the exception of mouse position, that is always correctly returned).
+//
+// For most cases, you want to use the 'xy' form. For example, you only want to receive
+// key down events for game character movement when the UI isn't capturing the keyboard,
+// because otherwise the character will move while typing in a UI textbox.
+//
+// The functions IsMouseCaptured and IsKeyboardCaptured are also available.
 package input
 
-import "github.com/veandco/go-sdl2/sdl"
+import (
+	"github.com/veandco/go-sdl2/sdl"
+)
 
 type keyState struct {
 	Key                 sdl.Keycode
@@ -31,15 +48,22 @@ type mouseWheelState struct {
 }
 
 var (
-	keyMap        = make(map[sdl.Keycode]keyState)
+	mouseWheel  = mouseWheelState{}
-	mouseBtnMap   = make(map[int]mouseBtnState)
+	mouseMotion = mouseMotionState{}
-	mouseMotion   = mouseMotionState{}
+	mouseBtnMap = make(map[int]mouseBtnState)
-	mouseWheel    = mouseWheelState{}
+	keyMap      = make(map[sdl.Keycode]keyState)
-	quitRequested bool
+
+	isQuitRequested    bool
+	isMouseCaptured    bool
+	isKeyboardCaptured bool
 )
 
-func EventLoopStart() {
+func EventLoopStart(mouseGotCaptured, keyboardGotCaptured bool) {
 
+	isMouseCaptured = mouseGotCaptured
+	isKeyboardCaptured = keyboardGotCaptured
+
+	// Update per-frame state
 	for k, v := range keyMap {
 		v.IsPressedThisFrame = false
 		v.IsReleasedThisFrame = false
@@ -59,7 +83,7 @@ func EventLoopStart() {
 	mouseWheel.XDelta = 0
 	mouseWheel.YDelta = 0
 
-	quitRequested = false
+	isQuitRequested = false
 }
 
 func ClearKeyboardState() {
@@ -73,11 +97,19 @@ func ClearMouseState() {
 }
 
 func HandleQuitEvent(e *sdl.QuitEvent) {
-	quitRequested = true
+	isQuitRequested = true
+}
+
+func IsMouseCaptured() bool {
+	return isMouseCaptured
+}
+
+func IsKeyboardCaptured() bool {
+	return isKeyboardCaptured
 }
 
 func IsQuitClicked() bool {
-	return quitRequested
+	return isQuitRequested
 }
 
 func HandleKeyboardEvent(e *sdl.KeyboardEvent) {
@@ -123,18 +155,36 @@ func HandleMouseWheelEvent(e *sdl.MouseWheelEvent) {
 	mouseWheel.YDelta = e.Y
 }
 
-// GetMousePos returns the window coordinates of the mouse
+// GetMousePos returns the window coordinates of the mouse regardless of whether the mouse is captured or not
 func GetMousePos() (x, y int32) {
 	return mouseMotion.XPos, mouseMotion.YPos
 }
 
 // GetMouseMotion returns how many pixels were moved last frame
 func GetMouseMotion() (xDelta, yDelta int32) {
+
+	if isMouseCaptured {
+		return 0, 0
+	}
+
+	return GetMouseMotionCaptured()
+}
+
+func GetMouseMotionCaptured() (xDelta, yDelta int32) {
 	return mouseMotion.XDelta, mouseMotion.YDelta
 }
 
 func GetMouseMotionNorm() (xDelta, yDelta int32) {
 
+	if isMouseCaptured {
+		return 0, 0
+	}
+
+	return GetMouseMotionNormCaptured()
+}
+
+func GetMouseMotionNormCaptured() (xDelta, yDelta int32) {
+
 	x, y := mouseMotion.XDelta, mouseMotion.YDelta
 	if x > 0 {
 		x = 1
@@ -152,12 +202,31 @@ func GetMouseMotionNorm() (xDelta, yDelta int32) {
 }
 
 func GetMouseWheelMotion() (xDelta, yDelta int32) {
+
+	if isMouseCaptured {
+		return 0, 0
+	}
+
+	return GetMouseWheelMotionCaptured()
+}
+
+func GetMouseWheelMotionCaptured() (xDelta, yDelta int32) {
 	return mouseWheel.XDelta, mouseWheel.YDelta
 }
 
 // GetMouseWheelXNorm returns 1 if mouse wheel xDelta > 0, -1 if xDelta < 0, and 0 otherwise
 func GetMouseWheelXNorm() int32 {
 
+	if isMouseCaptured {
+		return 0
+	}
+
+	return GetMouseWheelXNormCaptured()
+}
+
+// GetMouseWheelXNormCaptured returns 1 if mouse wheel xDelta > 0, -1 if xDelta < 0, and 0 otherwise
+func GetMouseWheelXNormCaptured() int32 {
+
 	if mouseWheel.XDelta > 0 {
 		return 1
 	} else if mouseWheel.XDelta < 0 {
@@ -167,9 +236,19 @@ func GetMouseWheelXNorm() int32 {
 	return 0
 }
 
-// returns 1 if mouse wheel yDelta > 0, -1 if yDelta < 0, and 0 otherwise
+// GetMouseWheelYNorm returns 1 if mouse wheel yDelta > 0, -1 if yDelta < 0, and 0 otherwise
 func GetMouseWheelYNorm() int32 {
 
+	if isMouseCaptured {
+		return 0
+	}
+
+	return GetMouseWheelYNormCaptured()
+}
+
+// GetMouseWheelYNormCaptured returns 1 if mouse wheel yDelta > 0, -1 if yDelta < 0, and 0 otherwise
+func GetMouseWheelYNormCaptured() int32 {
+
 	if mouseWheel.YDelta > 0 {
 		return 1
 	} else if mouseWheel.YDelta < 0 {
@@ -181,6 +260,15 @@ func GetMouseWheelYNorm() int32 {
 
 func KeyClicked(kc sdl.Keycode) bool {
 
+	if isKeyboardCaptured {
+		return false
+	}
+
+	return KeyClickedCaptured(kc)
+}
+
+func KeyClickedCaptured(kc sdl.Keycode) bool {
+
 	ks, ok := keyMap[kc]
 	if !ok {
 		return false
@@ -191,6 +279,15 @@ func KeyClicked(kc sdl.Keycode) bool {
 
 func KeyReleased(kc sdl.Keycode) bool {
 
+	if isKeyboardCaptured {
+		return false
+	}
+
+	return KeyReleasedCaptured(kc)
+}
+
+func KeyReleasedCaptured(kc sdl.Keycode) bool {
+
 	ks, ok := keyMap[kc]
 	if !ok {
 		return false
@@ -201,6 +298,15 @@ func KeyReleased(kc sdl.Keycode) bool {
 
 func KeyDown(kc sdl.Keycode) bool {
 
+	if isKeyboardCaptured {
+		return false
+	}
+
+	return KeyDownCaptured(kc)
+}
+
+func KeyDownCaptured(kc sdl.Keycode) bool {
+
 	ks, ok := keyMap[kc]
 	if !ok {
 		return false
@@ -211,6 +317,15 @@ func KeyDown(kc sdl.Keycode) bool {
 
 func KeyUp(kc sdl.Keycode) bool {
 
+	if isKeyboardCaptured {
+		return false
+	}
+
+	return KeyUpCaptured(kc)
+}
+
+func KeyUpCaptured(kc sdl.Keycode) bool {
+
 	ks, ok := keyMap[kc]
 	if !ok {
 		return true
@@ -221,6 +336,15 @@ func KeyUp(kc sdl.Keycode) bool {
 
 func MouseClicked(mb int) bool {
 
+	if isMouseCaptured {
+		return false
+	}
+
+	return MouseClickedCaptued(mb)
+}
+
+func MouseClickedCaptued(mb int) bool {
+
 	btn, ok := mouseBtnMap[mb]
 	if !ok {
 		return false
@@ -231,6 +355,15 @@ func MouseClicked(mb int) bool {
 
 func MouseDoubleClicked(mb int) bool {
 
+	if isMouseCaptured {
+		return false
+	}
+
+	return MouseDoubleClickedCaptured(mb)
+}
+
+func MouseDoubleClickedCaptured(mb int) bool {
+
 	btn, ok := mouseBtnMap[mb]
 	if !ok {
 		return false
@@ -240,6 +373,16 @@ func MouseDoubleClicked(mb int) bool {
 }
 
 func MouseReleased(mb int) bool {
+
+	if isMouseCaptured {
+		return false
+	}
+
+	return MouseReleasedCaptured(mb)
+}
+
+func MouseReleasedCaptured(mb int) bool {
+
 	btn, ok := mouseBtnMap[mb]
 	if !ok {
 		return false
@@ -250,6 +393,15 @@ func MouseReleased(mb int) bool {
 
 func MouseDown(mb int) bool {
 
+	if isMouseCaptured {
+		return false
+	}
+
+	return MouseDownCaptued(mb)
+}
+
+func MouseDownCaptued(mb int) bool {
+
 	btn, ok := mouseBtnMap[mb]
 	if !ok {
 		return false
@@ -260,6 +412,15 @@ func MouseDown(mb int) bool {
 
 func MouseUp(mb int) bool {
 
+	if isMouseCaptured {
+		return false
+	}
+
+	return MouseUpCaptured(mb)
+}
+
+func MouseUpCaptured(mb int) bool {
+
 	btn, ok := mouseBtnMap[mb]
 	if !ok {
 		return true