Handle relative mouse mode mouse pos for imgui

assets/textures.go

@@ -23,11 +23,20 @@ const (
 )
 
 type Texture struct {
-	//Path only exists for textures loaded from disk
-	Path   string
-	TexID  uint32
-	Width  int32
+	// Path only exists for textures loaded from disk
+	Path string
+
+	TexID uint32
+
+	// Width is the width of the texture in pixels (pixels per row).
+	// Note that the number of bytes constituting a row is MORE than this (e.g. for RGBA8, bytesPerRow=width*4, since we have 4 bytes per pixel)
+	Width int32
+
+	// Height is the height of the texture in pixels (pixels per column).
+	// Note that the number of bytes constituting a column is MORE than this (e.g. for RGBA8, bytesPerColumn=height*4, since we have 4 bytes per pixel)
 	Height int32
+
+	// Pixels usually stored in RGBA format
 	Pixels []byte
 }
 
@@ -36,6 +45,7 @@ type TextureLoadOptions struct {
 	WriteToCache     bool
 	GenMipMaps       bool
 	KeepPixelsInMem  bool
+	TextureIsSrgba   bool
 }
 
 type Cubemap struct {
@@ -77,10 +87,10 @@ func LoadTexturePNG(file string, loadOptions *TextureLoadOptions) (Texture, erro
 	tex := Texture{
 		Path:   file,
 		Pixels: nrgbaImg.Pix,
-		Height: int32(nrgbaImg.Bounds().Dy()),
 		Width:  int32(nrgbaImg.Bounds().Dx()),
+		Height: int32(nrgbaImg.Bounds().Dy()),
 	}
-	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height))
+	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height), 4)
 
 	//Prepare opengl stuff
 	gl.GenTextures(1, &tex.TexID)
@@ -93,7 +103,12 @@ func LoadTexturePNG(file string, loadOptions *TextureLoadOptions) (Texture, erro
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
 
 	// load and generate the texture
-	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.SRGB8_ALPHA8, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
+	internalFormat := int32(gl.RGBA8)
+	if loadOptions.TextureIsSrgba {
+		internalFormat = gl.SRGB_ALPHA
+	}
+
+	gl.TexImage2D(gl.TEXTURE_2D, 0, internalFormat, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
 
 	if loadOptions.GenMipMaps {
 		gl.GenerateMipmap(tex.TexID)
@@ -123,7 +138,7 @@ func LoadTextureInMemPngImg(img image.Image, loadOptions *TextureLoadOptions) (T
 		Height: int32(nrgbaImg.Bounds().Dy()),
 		Width:  int32(nrgbaImg.Bounds().Dx()),
 	}
-	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height))
+	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height), 4)
 
 	//Prepare opengl stuff
 	gl.GenTextures(1, &tex.TexID)
@@ -136,7 +151,12 @@ func LoadTextureInMemPngImg(img image.Image, loadOptions *TextureLoadOptions) (T
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
 
 	// load and generate the texture
-	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.SRGB8_ALPHA8, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
+	internalFormat := int32(gl.RGBA8)
+	if loadOptions.TextureIsSrgba {
+		internalFormat = gl.SRGB_ALPHA
+	}
+
+	gl.TexImage2D(gl.TEXTURE_2D, 0, internalFormat, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
 
 	if loadOptions.GenMipMaps {
 		gl.GenerateMipmap(tex.TexID)
@@ -183,7 +203,7 @@ func LoadTextureJpeg(file string, loadOptions *TextureLoadOptions) (Texture, err
 		Height: int32(nrgbaImg.Bounds().Dy()),
 		Width:  int32(nrgbaImg.Bounds().Dx()),
 	}
-	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height))
+	flipImgPixelsVertically(tex.Pixels, int(tex.Width), int(tex.Height), 4)
 
 	//Prepare opengl stuff
 	gl.GenTextures(1, &tex.TexID)
@@ -196,7 +216,12 @@ func LoadTextureJpeg(file string, loadOptions *TextureLoadOptions) (Texture, err
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
 
 	// load and generate the texture
-	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.SRGB8_ALPHA8, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
+	internalFormat := int32(gl.RGBA8)
+	if loadOptions.TextureIsSrgba {
+		internalFormat = gl.SRGB_ALPHA
+	}
+
+	gl.TexImage2D(gl.TEXTURE_2D, 0, internalFormat, tex.Width, tex.Height, 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&tex.Pixels[0]))
 
 	if loadOptions.GenMipMaps {
 		gl.GenerateMipmap(tex.TexID)
@@ -213,7 +238,12 @@ func LoadTextureJpeg(file string, loadOptions *TextureLoadOptions) (Texture, err
 	return tex, nil
 }
 
-func LoadCubemapTextures(rightTex, leftTex, topTex, botTex, frontTex, backTex string) (Cubemap, error) {
+// LoadCubemapTextures only supports the 'TextureIsSrgba' option
+func LoadCubemapTextures(rightTex, leftTex, topTex, botTex, frontTex, backTex string, loadOptions *TextureLoadOptions) (Cubemap, error) {
+
+	if loadOptions == nil {
+		loadOptions = &TextureLoadOptions{}
+	}
 
 	var imgDecoder func(r io.Reader) (image.Image, error)
 	ext := strings.ToLower(path.Ext(rightTex))
@@ -258,7 +288,12 @@ func LoadCubemapTextures(rightTex, leftTex, topTex, botTex, frontTex, backTex st
 		height := int32(nrgbaImg.Bounds().Dy())
 		width := int32(nrgbaImg.Bounds().Dx())
 
-		gl.TexImage2D(uint32(gl.TEXTURE_CUBE_MAP_POSITIVE_X)+i, 0, gl.RGBA8, int32(width), int32(height), 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&nrgbaImg.Pix[0]))
+		internalFormat := int32(gl.RGBA8)
+		if loadOptions.TextureIsSrgba {
+			internalFormat = gl.SRGB_ALPHA
+		}
+
+		gl.TexImage2D(uint32(gl.TEXTURE_CUBE_MAP_POSITIVE_X)+i, 0, internalFormat, int32(width), int32(height), 0, gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&nrgbaImg.Pix[0]))
 	}
 
 	// set the texture wrapping/filtering options (on the currently bound texture object)
@@ -271,19 +306,20 @@ func LoadCubemapTextures(rightTex, leftTex, topTex, botTex, frontTex, backTex st
 	return cmap, nil
 }
 
-func flipImgPixelsVertically(bytes []byte, width, height int) {
+func flipImgPixelsVertically(bytes []byte, width, height, bytesPerPixel int) {
 
 	// Flip the image vertically such that (e.g. in an image of 10 rows) rows 0<->9, 1<->8, 2<->7 etc are swapped.
 	// We do this because images are usually stored top-left to bottom-right, while opengl stores textures bottom-left to top-right, so if we don't swap
 	// rows textures will appear inverted
-	rowData := make([]byte, width)
+	widthInBytes := width * bytesPerPixel
+	rowData := make([]byte, width*bytesPerPixel)
 	for rowNum := 0; rowNum < height/2; rowNum++ {
 
-		upperRowStartIndex := rowNum * width
-		lowerRowStartIndex := (height - rowNum - 1) * width
-		copy(rowData, bytes[upperRowStartIndex:upperRowStartIndex+width])
-		copy(bytes[upperRowStartIndex:upperRowStartIndex+width], bytes[lowerRowStartIndex:lowerRowStartIndex+width])
-		copy(bytes[lowerRowStartIndex:lowerRowStartIndex+width], rowData)
+		upperRowStartIndex := rowNum * widthInBytes
+		lowerRowStartIndex := (height - rowNum - 1) * widthInBytes
+		copy(rowData, bytes[upperRowStartIndex:upperRowStartIndex+widthInBytes])
+		copy(bytes[upperRowStartIndex:upperRowStartIndex+widthInBytes], bytes[lowerRowStartIndex:lowerRowStartIndex+widthInBytes])
+		copy(bytes[lowerRowStartIndex:lowerRowStartIndex+widthInBytes], rowData)
 
 	}
 }

engine/engine.go

@@ -15,6 +15,13 @@ import (
 
 var (
 	isInited = false
+
+	isSdlButtonLeftDown   = false
+	isSdlButtonMiddleDown = false
+	isSdlButtonRightDown  = false
+
+	ImguiRelativeMouseModePosX float32
+	ImguiRelativeMouseModePosY float32
 )
 
 type Window struct {
@@ -29,7 +36,9 @@ func (w *Window) handleInputs() {
 	input.EventLoopStart()
 	imIo := imgui.CurrentIO()
 
-	// @TODO: Would be nice to have imgui package process its own events via a callback instead of it being part of engine code
+	imguiCaptureMouse := imIo.WantCaptureMouse()
+	imguiCaptureKeyboard := imIo.WantCaptureKeyboard()
+
 	for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
 
 		//Fire callbacks
@@ -42,14 +51,18 @@ func (w *Window) handleInputs() {
 
 		case *sdl.MouseWheelEvent:
 
-			input.HandleMouseWheelEvent(e)
+			if !imguiCaptureMouse {
+				input.HandleMouseWheelEvent(e)
+			}
 
-			xDelta, yDelta := input.GetMouseWheelMotion()
-			imIo.AddMouseWheelDelta(float32(xDelta), float32(yDelta))
+			imIo.AddMouseWheelDelta(float32(e.X), float32(e.Y))
 
 		case *sdl.KeyboardEvent:
 
-			input.HandleKeyboardEvent(e)
+			if !imguiCaptureKeyboard {
+				input.HandleKeyboardEvent(e)
+			}
+
 			imIo.AddKeyEvent(nmageimgui.SdlScancodeToImGuiKey(e.Keysym.Scancode), e.Type == sdl.KEYDOWN)
 
 			// Send modifier key updates to imgui
@@ -73,12 +86,29 @@ func (w *Window) handleInputs() {
 			imIo.AddInputCharactersUTF8(e.GetText())
 
 		case *sdl.MouseButtonEvent:
-			input.HandleMouseBtnEvent(e)
+
+			if !imguiCaptureMouse {
+				input.HandleMouseBtnEvent(e)
+			}
+
+			isPressed := e.State == sdl.PRESSED
+
+			if e.Button == sdl.BUTTON_LEFT {
+				isSdlButtonLeftDown = isPressed
+			} else if e.Button == sdl.BUTTON_MIDDLE {
+				isSdlButtonMiddleDown = isPressed
+			} else if e.Button == sdl.BUTTON_RIGHT {
+				isSdlButtonRightDown = isPressed
+			}
 
 		case *sdl.MouseMotionEvent:
-			input.HandleMouseMotionEvent(e)
+
+			if !imguiCaptureMouse {
+				input.HandleMouseMotionEvent(e)
+			}
 
 		case *sdl.WindowEvent:
+
 			if e.Event == sdl.WINDOWEVENT_SIZE_CHANGED {
 				w.handleWindowResize()
 			}
@@ -88,13 +118,17 @@ func (w *Window) handleInputs() {
 		}
 	}
 
-	// If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
-	x, y, _ := sdl.GetMouseState()
-	imIo.SetMousePos(imgui.Vec2{X: float32(x), Y: float32(y)})
+	if sdl.GetRelativeMouseMode() {
+		imIo.SetMousePos(imgui.Vec2{X: ImguiRelativeMouseModePosX, Y: ImguiRelativeMouseModePosY})
+	} else {
+		x, y, _ := sdl.GetMouseState()
+		imIo.SetMousePos(imgui.Vec2{X: float32(x), Y: float32(y)})
+	}
 
-	imIo.SetMouseButtonDown(0, input.MouseDown(sdl.BUTTON_LEFT))
-	imIo.SetMouseButtonDown(1, input.MouseDown(sdl.BUTTON_RIGHT))
-	imIo.SetMouseButtonDown(2, input.MouseDown(sdl.BUTTON_MIDDLE))
+	// If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
+	imIo.SetMouseButtonDown(imgui.MouseButtonLeft, isSdlButtonLeftDown)
+	imIo.SetMouseButtonDown(imgui.MouseButtonRight, isSdlButtonRightDown)
+	imIo.SetMouseButtonDown(imgui.MouseButtonMiddle, isSdlButtonMiddleDown)
 }
 
 func (w *Window) handleWindowResize() {
@@ -133,15 +167,21 @@ func initSDL() error {
 	sdl.GLSetAttribute(sdl.MAJOR_VERSION, 4)
 	sdl.GLSetAttribute(sdl.MINOR_VERSION, 1)
 
-	// R(0-255) G(0-255) B(0-255)
 	sdl.GLSetAttribute(sdl.GL_RED_SIZE, 8)
 	sdl.GLSetAttribute(sdl.GL_GREEN_SIZE, 8)
 	sdl.GLSetAttribute(sdl.GL_BLUE_SIZE, 8)
+	sdl.GLSetAttribute(sdl.GL_ALPHA_SIZE, 8)
 
 	sdl.GLSetAttribute(sdl.GL_DOUBLEBUFFER, 1)
 	sdl.GLSetAttribute(sdl.GL_DEPTH_SIZE, 24)
 	sdl.GLSetAttribute(sdl.GL_STENCIL_SIZE, 8)
 
+	sdl.GLSetAttribute(sdl.GL_FRAMEBUFFER_SRGB_CAPABLE, 1)
+
+	// Allows us to do MSAA
+	sdl.GLSetAttribute(sdl.GL_MULTISAMPLEBUFFERS, 1)
+	sdl.GLSetAttribute(sdl.GL_MULTISAMPLESAMPLES, 4)
+
 	sdl.GLSetAttribute(sdl.GL_CONTEXT_PROFILE_MASK, sdl.GL_CONTEXT_PROFILE_CORE)
 
 	return nil
@@ -152,16 +192,12 @@ func CreateOpenGLWindow(title string, x, y, width, height int32, flags WindowFla
 }
 
 func CreateOpenGLWindowCentered(title string, width, height int32, flags WindowFlags, rend renderer.Render) (*Window, error) {
-	return createWindow(title, -1, -1, width, height, WindowFlags_OPENGL|flags, rend)
+	return createWindow(title, sdl.WINDOWPOS_CENTERED, sdl.WINDOWPOS_CENTERED, width, height, WindowFlags_OPENGL|flags, rend)
 }
 
 func createWindow(title string, x, y, width, height int32, flags WindowFlags, rend renderer.Render) (*Window, error) {
 
-	assert.T(isInited, "engine.Init was not called!")
-	if x == -1 && y == -1 {
-		x = sdl.WINDOWPOS_CENTERED
-		y = sdl.WINDOWPOS_CENTERED
-	}
+	assert.T(isInited, "engine.Init() was not called!")
 
 	sdlWin, err := sdl.CreateWindow(title, x, y, width, height, uint32(flags))
 	if err != nil {
@@ -198,12 +234,23 @@ func initOpenGL() error {
 	gl.FrontFace(gl.CCW)
 
 	gl.Enable(gl.BLEND)
+	gl.Enable(gl.MULTISAMPLE)
+	gl.Enable(gl.FRAMEBUFFER_SRGB)
 	gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
 
 	gl.ClearColor(0, 0, 0, 1)
 	return nil
 }
 
+func SetSrgbFramebuffer(isEnabled bool) {
+
+	if isEnabled {
+		gl.Enable(gl.FRAMEBUFFER_SRGB)
+	} else {
+		gl.Disable(gl.FRAMEBUFFER_SRGB)
+	}
+}
+
 func SetVSync(enabled bool) {
 	assert.T(isInited, "engine.Init was not called!")
 
@@ -213,3 +260,12 @@ func SetVSync(enabled bool) {
 		sdl.GLSetSwapInterval(0)
 	}
 }
+
+func SetMSAA(isEnabled bool) {
+
+	if isEnabled {
+		gl.Enable(gl.MULTISAMPLE)
+	} else {
+		gl.Disable(gl.MULTISAMPLE)
+	}
+}

go.mod

@@ -11,9 +11,9 @@ require (
 	github.com/bloeys/gglm v0.43.0
 )
 
-require github.com/AllenDang/cimgui-go v0.0.0-20230720025235-f2ff398a66b2
-
 require (
-	github.com/mandykoh/go-parallel v0.1.0 // indirect
-	github.com/mandykoh/prism v0.35.1 // indirect
+	github.com/AllenDang/cimgui-go v0.0.0-20230720025235-f2ff398a66b2
+	github.com/mandykoh/prism v0.35.1
 )
+
+require github.com/mandykoh/go-parallel v0.1.0 // indirect

go.sum

@@ -15,6 +15,7 @@ github.com/veandco/go-sdl2 v0.4.35/go.mod h1:OROqMhHD43nT4/i9crJukyVecjPNYYuCofe
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/image v0.5.0 h1:5JMiNunQeQw++mMOz48/ISeNu3Iweh/JaZU8ZLqHRrI=
 golang.org/x/image v0.5.0/go.mod h1:FVC7BI/5Ym8R25iw5OLsgshdUBbT1h5jZTpA+mvAdZ4=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=

input/input.go

@@ -31,8 +31,8 @@ type mouseWheelState struct {
 }
 
 var (
-	keyMap        = make(map[sdl.Keycode]*keyState)
-	mouseBtnMap   = make(map[int]*mouseBtnState)
+	keyMap        = make(map[sdl.Keycode]keyState)
+	mouseBtnMap   = make(map[int]mouseBtnState)
 	mouseMotion   = mouseMotionState{}
 	mouseWheel    = mouseWheelState{}
 	quitRequested bool
@@ -70,29 +70,31 @@ func IsQuitClicked() bool {
 
 func HandleKeyboardEvent(e *sdl.KeyboardEvent) {
 
-	ks := keyMap[e.Keysym.Sym]
-	if ks == nil {
-		ks = &keyState{Key: e.Keysym.Sym}
-		keyMap[ks.Key] = ks
+	ks, ok := keyMap[e.Keysym.Sym]
+	if !ok {
+		ks = keyState{Key: e.Keysym.Sym}
 	}
 
 	ks.State = int(e.State)
 	ks.IsPressedThisFrame = e.State == sdl.PRESSED && e.Repeat == 0
 	ks.IsReleasedThisFrame = e.State == sdl.RELEASED && e.Repeat == 0
+
+	keyMap[ks.Key] = ks
 }
 
 func HandleMouseBtnEvent(e *sdl.MouseButtonEvent) {
 
-	mb := mouseBtnMap[int(e.Button)]
-	if mb == nil {
-		mb = &mouseBtnState{Btn: int(e.Button)}
-		mouseBtnMap[int(e.Button)] = mb
+	mb, ok := mouseBtnMap[int(e.Button)]
+	if !ok {
+		mb = mouseBtnState{Btn: int(e.Button)}
 	}
 
 	mb.State = int(e.State)
 	mb.IsDoubleClicked = e.Clicks == 2 && e.State == sdl.PRESSED
 	mb.IsPressedThisFrame = e.State == sdl.PRESSED
 	mb.IsReleasedThisFrame = e.State == sdl.RELEASED
+
+	mouseBtnMap[int(e.Button)] = mb
 }
 
 func HandleMouseMotionEvent(e *sdl.MouseMotionEvent) {
@@ -109,12 +111,12 @@ 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
 func GetMousePos() (x, y int32) {
 	return mouseMotion.XPos, mouseMotion.YPos
 }
 
-//GetMouseMotion returns how many pixels were moved last frame
+// GetMouseMotion returns how many pixels were moved last frame
 func GetMouseMotion() (xDelta, yDelta int32) {
 	return mouseMotion.XDelta, mouseMotion.YDelta
 }
@@ -141,7 +143,7 @@ func GetMouseWheelMotion() (xDelta, yDelta int32) {
 	return mouseWheel.XDelta, mouseWheel.YDelta
 }
 
-//GetMouseWheelXNorm returns 1 if mouse wheel xDelta > 0, -1 if xDelta < 0, and 0 otherwise
+// GetMouseWheelXNorm returns 1 if mouse wheel xDelta > 0, -1 if xDelta < 0, and 0 otherwise
 func GetMouseWheelXNorm() int32 {
 
 	if mouseWheel.XDelta > 0 {
@@ -153,7 +155,7 @@ func GetMouseWheelXNorm() int32 {
 	return 0
 }
 
-//returns 1 if mouse wheel yDelta > 0, -1 if yDelta < 0, and 0 otherwise
+// returns 1 if mouse wheel yDelta > 0, -1 if yDelta < 0, and 0 otherwise
 func GetMouseWheelYNorm() int32 {
 
 	if mouseWheel.YDelta > 0 {
@@ -167,8 +169,8 @@ func GetMouseWheelYNorm() int32 {
 
 func KeyClicked(kc sdl.Keycode) bool {
 
-	ks := keyMap[kc]
-	if ks == nil {
+	ks, ok := keyMap[kc]
+	if !ok {
 		return false
 	}
 
@@ -177,8 +179,8 @@ func KeyClicked(kc sdl.Keycode) bool {
 
 func KeyReleased(kc sdl.Keycode) bool {
 
-	ks := keyMap[kc]
-	if ks == nil {
+	ks, ok := keyMap[kc]
+	if !ok {
 		return false
 	}
 
@@ -187,8 +189,8 @@ func KeyReleased(kc sdl.Keycode) bool {
 
 func KeyDown(kc sdl.Keycode) bool {
 
-	ks := keyMap[kc]
-	if ks == nil {
+	ks, ok := keyMap[kc]
+	if !ok {
 		return false
 	}
 
@@ -197,8 +199,8 @@ func KeyDown(kc sdl.Keycode) bool {
 
 func KeyUp(kc sdl.Keycode) bool {
 
-	ks := keyMap[kc]
-	if ks == nil {
+	ks, ok := keyMap[kc]
+	if !ok {
 		return true
 	}
 
@@ -207,8 +209,8 @@ func KeyUp(kc sdl.Keycode) bool {
 
 func MouseClicked(mb int) bool {
 
-	btn := mouseBtnMap[mb]
-	if btn == nil {
+	btn, ok := mouseBtnMap[mb]
+	if !ok {
 		return false
 	}
 
@@ -217,8 +219,8 @@ func MouseClicked(mb int) bool {
 
 func MouseDoubleClicked(mb int) bool {
 
-	btn := mouseBtnMap[mb]
-	if btn == nil {
+	btn, ok := mouseBtnMap[mb]
+	if !ok {
 		return false
 	}
 
@@ -226,8 +228,8 @@ func MouseDoubleClicked(mb int) bool {
 }
 
 func MouseReleased(mb int) bool {
-	btn := mouseBtnMap[mb]
-	if btn == nil {
+	btn, ok := mouseBtnMap[mb]
+	if !ok {
 		return false
 	}
 
@@ -236,8 +238,8 @@ func MouseReleased(mb int) bool {
 
 func MouseDown(mb int) bool {
 
-	btn := mouseBtnMap[mb]
-	if btn == nil {
+	btn, ok := mouseBtnMap[mb]
+	if !ok {
 		return false
 	}
 
@@ -246,8 +248,8 @@ func MouseDown(mb int) bool {
 
 func MouseUp(mb int) bool {
 
-	btn := mouseBtnMap[mb]
-	if btn == nil {
+	btn, ok := mouseBtnMap[mb]
+	if !ok {
 		return true
 	}
 

main.go

@@ -141,11 +141,13 @@ func main() {
 	}
 	defer window.Destroy()
 
+	engine.SetMSAA(true)
 	engine.SetVSync(false)
+	engine.SetSrgbFramebuffer(true)
 
 	game := &OurGame{
 		Win:       window,
-		ImGUIInfo: nmageimgui.NewImGui(),
+		ImGUIInfo: nmageimgui.NewImGui("./res/shaders/imgui.glsl"),
 	}
 	window.EventCallbacks = append(window.EventCallbacks, game.handleWindowEvents)
 
@@ -229,7 +231,7 @@ func (g *OurGame) Init() {
 	}
 
 	//Load textures
-	tex, err := assets.LoadTexturePNG("./res/textures/pallete-endesga-64-1x.png", nil)
+	tex, err := assets.LoadTexturePNG("./res/textures/pallete-endesga-64-1x.png", &assets.TextureLoadOptions{TextureIsSrgba: true})
 	if err != nil {
 		logging.ErrLog.Fatalln("Failed to load texture. Err: ", err)
 	}
@@ -238,6 +240,7 @@ func (g *OurGame) Init() {
 		"./res/textures/sb-right.jpg", "./res/textures/sb-left.jpg",
 		"./res/textures/sb-top.jpg", "./res/textures/sb-bottom.jpg",
 		"./res/textures/sb-front.jpg", "./res/textures/sb-back.jpg",
+		&assets.TextureLoadOptions{TextureIsSrgba: true},
 	)
 	if err != nil {
 		logging.ErrLog.Fatalln("Failed to load cubemap. Err: ", err)
@@ -271,6 +274,8 @@ func (g *OurGame) Init() {
 	//Lights
 	simpleMat.SetUnifVec3("lightPos1", lightPos1)
 	simpleMat.SetUnifVec3("lightColor1", lightColor1)
+
+	sdl.SetRelativeMouseMode(true)
 }
 
 func (g *OurGame) Update() {

registry/registry.go

@@ -77,6 +77,10 @@ func (r *Registry[T]) New() (*T, Handle) {
 
 func (r *Registry[T]) Get(id Handle) *T {
 
+	if id.IsZero() {
+		return nil
+	}
+
 	index := id.Index()
 	assert.T(index < uint64(len(r.Handles)), "Failed to get entity because of invalid entity handle. Handle index is %d while registry only has %d slots. Handle: %+v", index, r.ItemCount, id)
 

registry/registry_handle.go

@@ -16,6 +16,12 @@ const (
 // Byte 1: Generation; Byte 2: Flags; Bytes 3-8: Index
 type Handle uint64
 
+// IsZero reports whether the handle is in its default 'zero' state.
+// A zero handle is an invalid handle that does NOT point to any entity
+func (h Handle) IsZero() bool {
+	return h == 0
+}
+
 func (h Handle) HasFlag(ef HandleFlag) bool {
 	return h.Flags()&ef > 0
 }

res/shaders/imgui.glsl

@@ -0,0 +1,47 @@
+//shader:vertex
+#version 410
+
+uniform mat4 ProjMtx;
+
+in vec2 Position;
+in vec2 UV;
+in vec4 Color;
+
+out vec2 Frag_UV;
+out vec4 Frag_Color;
+
+// Imgui doesn't handle srgb correctly, and looks too bright and wrong in srgb buffers (see: https://github.com/ocornut/imgui/issues/578).
+// While not a complete fix (that would require changes in imgui itself), moving incoming srgba colors to linear in the vertex shader helps make things look better.
+vec4 srgba_to_linear(vec4 srgbaColor){
+
+    #define gamma_correction 2.2
+
+    return vec4(
+        pow(srgbaColor.r, gamma_correction),
+        pow(srgbaColor.g, gamma_correction),
+        pow(srgbaColor.b, gamma_correction),
+        srgbaColor.a
+    );
+}
+
+void main()
+{
+    Frag_UV = UV;
+    Frag_Color = srgba_to_linear(Color);
+    gl_Position = ProjMtx * vec4(Position.xy, 0, 1);
+}
+
+//shader:fragment
+#version 410
+
+uniform sampler2D Texture;
+
+in vec2 Frag_UV;
+in vec4 Frag_Color;
+
+out vec4 Out_Color;
+
+void main()
+{
+    Out_Color = vec4(Frag_Color.rgb, Frag_Color.a * texture(Texture, Frag_UV.st).r);
+}

ui/imgui/imgui.go

@@ -16,7 +16,8 @@ type ImguiInfo struct {
 	VaoID      uint32
 	VboID      uint32
 	IndexBufID uint32
-	TexID      uint32
+	// This is a pointer so we can send a stable pointer to C code
+	TexID *uint32
 }
 
 func (i *ImguiInfo) FrameStart(winWidth, winHeight float32) {
@@ -67,7 +68,7 @@ func (i *ImguiInfo) Render(winWidth, winHeight float32, fbWidth, fbHeight int32)
 	i.Mat.Bind()
 	i.Mat.SetUnifInt32("Texture", 0)
 
-	//PERF: only update the ortho matrix on window resize
+	// @PERF: only update the ortho matrix on window resize
 	orthoMat := gglm.Ortho(0, float32(winWidth), 0, float32(winHeight), 0, 20)
 	i.Mat.SetUnifMat4("ProjMtx", &orthoMat.Mat4)
 	gl.BindSampler(0, 0) // Rely on combined texture/sampler state.
@@ -108,11 +109,11 @@ func (i *ImguiInfo) Render(winWidth, winHeight float32, fbWidth, fbHeight int32)
 				cmd.CallUserCallback(list)
 			} else {
 
-				gl.BindTexture(gl.TEXTURE_2D, i.TexID)
+				gl.BindTexture(gl.TEXTURE_2D, *i.TexID)
 				clipRect := cmd.ClipRect()
 				gl.Scissor(int32(clipRect.X), int32(fbHeight)-int32(clipRect.W), int32(clipRect.Z-clipRect.X), int32(clipRect.W-clipRect.Y))
 
-				gl.DrawElementsBaseVertex(gl.TRIANGLES, int32(cmd.ElemCount()), uint32(drawType), gl.PtrOffset(int(cmd.IdxOffset())*indexSize), int32(cmd.VtxOffset()))
+				gl.DrawElementsBaseVertexWithOffset(gl.TRIANGLES, int32(cmd.ElemCount()), uint32(drawType), uintptr(int(cmd.IdxOffset())*indexSize), int32(cmd.VtxOffset()))
 			}
 		}
 	}
@@ -141,13 +142,13 @@ func (i *ImguiInfo) AddFontTTF(fontPath string, fontSize float32, fontConfig *im
 	f := a.AddFontFromFileTTFV(fontPath, fontSize, fontConfigToUse, glyphRangesToUse.Data())
 	pixels, width, height, _ := a.GetTextureDataAsAlpha8()
 
-	gl.BindTexture(gl.TEXTURE_2D, i.TexID)
+	gl.BindTexture(gl.TEXTURE_2D, *i.TexID)
 	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RED, int32(width), int32(height), 0, gl.RED, gl.UNSIGNED_BYTE, pixels)
 
 	return f
 }
 
-const imguiShdrSrc = `
+const DefaultImguiShader = `
 //shader:vertex
 #version 410
 
@@ -160,10 +161,24 @@ in vec4 Color;
 out vec2 Frag_UV;
 out vec4 Frag_Color;
 
+// Imgui doesn't handle srgb correctly, and looks too bright and wrong in srgb buffers (see: https://github.com/ocornut/imgui/issues/578).
+// While not a complete fix (that would require changes in imgui itself), moving incoming srgba colors to linear in the vertex shader helps make things look better.
+vec4 srgba_to_linear(vec4 srgbaColor){
+
+    #define gamma_correction 2.2
+
+    return vec4(
+        pow(srgbaColor.r, gamma_correction),
+        pow(srgbaColor.g, gamma_correction),
+        pow(srgbaColor.b, gamma_correction),
+        srgbaColor.a
+    );
+}
+
 void main()
 {
     Frag_UV = UV;
-    Frag_Color = Color;
+    Frag_Color = srgba_to_linear(Color);
     gl_Position = ProjMtx * vec4(Position.xy, 0, 1);
 }
 
@@ -183,11 +198,21 @@ void main()
 }
 `
 
-func NewImGui() ImguiInfo {
+// NewImGui setups imgui using the passed shader.
+// If the path is empty a default nMage shader is used
+func NewImGui(shaderPath string) ImguiInfo {
+
+	var imguiMat *materials.Material
+	if shaderPath == "" {
+		imguiMat = materials.NewMaterialSrc("ImGUI Mat", []byte(DefaultImguiShader))
+	} else {
+		imguiMat = materials.NewMaterial("ImGUI Mat", shaderPath)
+	}
 
 	imguiInfo := ImguiInfo{
 		ImCtx: imgui.CreateContext(),
-		Mat:   materials.NewMaterialSrc("ImGUI Mat", []byte(imguiShdrSrc)),
+		Mat:   imguiMat,
+		TexID: new(uint32),
 	}
 
 	io := imgui.CurrentIO()
@@ -197,10 +222,10 @@ func NewImGui() ImguiInfo {
 	gl.GenVertexArrays(1, &imguiInfo.VaoID)
 	gl.GenBuffers(1, &imguiInfo.VboID)
 	gl.GenBuffers(1, &imguiInfo.IndexBufID)
-	gl.GenTextures(1, &imguiInfo.TexID)
+	gl.GenTextures(1, imguiInfo.TexID)
 
 	// Upload font to gpu
-	gl.BindTexture(gl.TEXTURE_2D, imguiInfo.TexID)
+	gl.BindTexture(gl.TEXTURE_2D, *imguiInfo.TexID)
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
 	gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
 	gl.PixelStorei(gl.UNPACK_ROW_LENGTH, 0)
@@ -209,7 +234,7 @@ func NewImGui() ImguiInfo {
 	gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RED, int32(width), int32(height), 0, gl.RED, gl.UNSIGNED_BYTE, pixels)
 
 	// Store our identifier
-	io.Fonts().SetTexID(imgui.TextureID(uintptr(imguiInfo.TexID)))
+	io.Fonts().SetTexID(imgui.TextureID(imguiInfo.TexID))
 
 	//Shader attributes
 	imguiInfo.Mat.Bind()