Remove 'default framebuffer' and add 'screen framebuffer' for iOS

graphicscontext.go

@@ -28,29 +28,29 @@ func newGraphicsContext(f func(*Image) error) *graphicsContext {
 
 type graphicsContext struct {
 	f           func(*Image) error
+	offscreen   *Image
 	screen      *Image
-	defaultRenderTarget *Image
 	screenScale int
 	initialized bool
 }
 
 func (c *graphicsContext) SetSize(screenWidth, screenHeight, screenScale int) error {
-	if c.defaultRenderTarget != nil {
-		c.defaultRenderTarget.Dispose()
-	}
 	if c.screen != nil {
 		c.screen.Dispose()
 	}
-	screen, err := NewImage(screenWidth, screenHeight, FilterNearest)
+	if c.offscreen != nil {
+		c.offscreen.Dispose()
+	}
+	offscreen, err := NewImage(screenWidth, screenHeight, FilterNearest)
 	if err != nil {
 		return err
 	}
-	c.defaultRenderTarget, err = newImageWithZeroFramebuffer(screenWidth*screenScale, screenHeight*screenScale)
+	c.screen, err = newImageWithScreenFramebuffer(screenWidth*screenScale, screenHeight*screenScale)
 	if err != nil {
 		return err
 	}
-	c.defaultRenderTarget.Clear()
+	c.screen.Clear()
-	c.screen = screen
+	c.offscreen = offscreen
 	c.screenScale = screenScale
 	return nil
 }
@@ -58,11 +58,11 @@ func (c *graphicsContext) SetSize(screenWidth, screenHeight, screenScale int) er
 func (c *graphicsContext) needsRestoring(context *opengl.Context) (bool, error) {
 	imageM.Lock()
 	defer imageM.Unlock()
-	// FlushCommands is required because c.screen.impl might not have an actual texture.
+	// FlushCommands is required because c.offscreen.impl might not have an actual texture.
 	if err := graphics.FlushCommands(ui.GLContext()); err != nil {
 		return false, err
 	}
-	return c.screen.impl.isInvalidated(context), nil
+	return c.offscreen.impl.isInvalidated(context), nil
 }
 
 func (c *graphicsContext) initializeIfNeeded() error {
@@ -85,13 +85,13 @@ func (c *graphicsContext) initializeIfNeeded() error {
 }
 
 func (c *graphicsContext) drawToDefaultRenderTarget() error {
-	if err := c.defaultRenderTarget.Clear(); err != nil {
+	if err := c.screen.Clear(); err != nil {
 		return err
 	}
 	scale := float64(c.screenScale)
 	options := &DrawImageOptions{}
 	options.GeoM.Scale(scale, scale)
-	if err := c.defaultRenderTarget.DrawImage(c.screen, options); err != nil {
+	if err := c.screen.DrawImage(c.offscreen, options); err != nil {
 		return err
 	}
 	if err := c.flush(); err != nil {
@@ -104,10 +104,10 @@ func (c *graphicsContext) UpdateAndDraw() error {
 	if err := c.initializeIfNeeded(); err != nil {
 		return err
 	}
-	if err := c.screen.Clear(); err != nil {
+	if err := c.offscreen.Clear(); err != nil {
 		return err
 	}
-	if err := c.f(c.screen); err != nil {
+	if err := c.f(c.offscreen); err != nil {
 		return err
 	}
 	if IsRunningSlowly() {
@@ -117,8 +117,8 @@ func (c *graphicsContext) UpdateAndDraw() error {
 		return err
 	}
 	exceptions := map[*imageImpl]struct{}{
+		c.offscreen.impl: {},
 		c.screen.impl:    {},
-		c.defaultRenderTarget.impl: {},
 	}
 	if err := theImages.savePixels(ui.GLContext(), exceptions); err != nil {
 		return err

image.go

@@ -78,7 +78,7 @@ func (i *images) restorePixels(context *opengl.Context) error {
 	i.m.Lock()
 	defer i.m.Unlock()
 	for img := range i.images {
-		if img.defaultFramebuffer {
+		if img.screen {
 			continue
 		}
 		if img.isDisposed() {
@@ -192,7 +192,7 @@ func (i *Image) ReplacePixels(p []uint8) error {
 
 type imageImpl struct {
 	image    *graphics.Image
-	defaultFramebuffer bool
+	screen   bool
 	disposed bool
 	width    int
 	height   int
@@ -285,7 +285,7 @@ func (i *imageImpl) savePixels(context *opengl.Context) error {
 }
 
 func (i *imageImpl) restorePixels(context *opengl.Context) error {
-	if i.defaultFramebuffer {
+	if i.screen {
 		return nil
 	}
 	if i.disposed {
@@ -433,10 +433,10 @@ func NewImageFromImage(source image.Image, filter Filter) (*Image, error) {
 	return eimg, nil
 }
 
-func newImageWithZeroFramebuffer(width, height int) (*Image, error) {
+func newImageWithScreenFramebuffer(width, height int) (*Image, error) {
 	imageM.Lock()
 	defer imageM.Unlock()
-	i, err := graphics.NewZeroFramebufferImage(width, height)
+	i, err := graphics.NewScreenFramebufferImage(width, height)
 	if err != nil {
 		return nil, err
 	}
@@ -444,7 +444,7 @@ func newImageWithZeroFramebuffer(width, height int) (*Image, error) {
 		image:  i,
 		width:  width,
 		height: height,
-		defaultFramebuffer: true,
+		screen: true,
 	}
 	eimg, err := theImages.add(img)
 	if err != nil {

internal/graphics/command.go

@@ -151,7 +151,7 @@ type disposeCommand struct {
 }
 
 func (c *disposeCommand) Exec(context *opengl.Context) error {
-	if c.target.framebuffer != nil && c.target.framebuffer.native != opengl.ZeroFramebuffer {
+	if c.target.framebuffer != nil && c.target.framebuffer.native != context.ScreenFramebuffer() {
 		context.DeleteFramebuffer(c.target.framebuffer.native)
 	}
 	if c.target.texture != nil {
@@ -245,3 +245,26 @@ func (c *newImageCommand) Exec(context *opengl.Context) error {
 	}
 	return nil
 }
+
+type newScreenFramebufferImageCommand struct {
+	result *Image
+	width  int
+	height int
+}
+
+func (c *newScreenFramebufferImageCommand) Exec(context *opengl.Context) error {
+	if c.width < 4 {
+		return errors.New("graphics: width must be equal or more than 4.")
+	}
+	if c.height < 4 {
+		return errors.New("graphics: height must be equal or more than 4.")
+	}
+	f := &framebuffer{
+		native: context.ScreenFramebuffer(),
+		width:  c.width,
+		height: c.height,
+		flipY:  true,
+	}
+	c.result.framebuffer = f
+	return nil
+}

internal/graphics/image.go

@@ -49,15 +49,15 @@ func NewImageFromImage(img *image.RGBA, filter opengl.Filter) (*Image, error) {
 	return i, nil
 }
 
-func NewZeroFramebufferImage(width, height int) (*Image, error) {
+func NewScreenFramebufferImage(width, height int) (*Image, error) {
-	f := &framebuffer{
+	i := &Image{}
+	c := &newScreenFramebufferImageCommand{
+		result: i,
 		width:  width,
 		height: height,
-		flipY:  true,
 	}
-	return &Image{
+	theCommandQueue.Enqueue(c)
-		framebuffer: f,
+	return i, nil
-	}, nil
 }
 
 func (i *Image) Dispose() error {

internal/graphics/opengl/context.go

@@ -14,8 +14,6 @@
 
 package opengl
 
-var ZeroFramebuffer Framebuffer
-
 type Context struct {
 	Nearest            Filter
 	Linear             Filter
@@ -34,6 +32,7 @@ type Context struct {
 	oneMinusSrcAlpha   operation
 	oneMinusDstAlpha   operation
 	locationCache      *locationCache
+	screenFramebuffer  Framebuffer // This might not be the default frame buffer '0' (e.g. iOS).
 	lastFramebuffer    Framebuffer
 	lastViewportWidth  int
 	lastViewportHeight int
@@ -48,3 +47,7 @@ func (c *Context) bindFramebuffer(f Framebuffer) {
 	c.bindFramebufferImpl(f)
 	c.lastFramebuffer = f
 }
+
+func (c *Context) ScreenFramebuffer() Framebuffer {
+	return c.screenFramebuffer
+}

internal/graphics/opengl/context_desktop.go

@@ -37,6 +37,8 @@ type attribLocation int32
 
 type programID uint32
 
+const invalidFramebuffer = (1 << 32) - 1
+
 func (p Program) id() programID {
 	return programID(p)
 }
@@ -102,17 +104,23 @@ func (c *Context) Init() error {
 		return err
 	}
 	c.BlendFunc(CompositeModeSourceOver)
+	f := int32(0)
+	gl.GetIntegerv(gl.FRAMEBUFFER_BINDING, &f)
+	c.screenFramebuffer = Framebuffer(f)
 	return nil
 }
 
 func (c *Context) Resume() {
 	c.locationCache = newLocationCache()
-	c.lastFramebuffer = ZeroFramebuffer
+	c.lastFramebuffer = invalidFramebuffer
 	c.lastViewportWidth = 0
 	c.lastViewportHeight = 0
 	c.lastCompositeMode = CompositeModeUnknown
 	gl.Enable(gl.BLEND)
 	c.BlendFunc(CompositeModeSourceOver)
+	f := int32(0)
+	gl.GetIntegerv(gl.FRAMEBUFFER_BINDING, &f)
+	c.screenFramebuffer = Framebuffer(f)
 }
 
 func (c *Context) BlendFunc(mode CompositeMode) {
@@ -212,9 +220,9 @@ func (c *Context) TexSubImage2D(p []uint8, width, height int) {
 	})
 }
 
-func (c *Context) BindZeroFramebuffer() {
+func (c *Context) BindScreenFramebuffer() {
 	c.RunOnContextThread(func() error {
-		c.bindFramebuffer(ZeroFramebuffer)
+		c.bindFramebuffer(c.screenFramebuffer)
 		return nil
 	})
 }
@@ -275,11 +283,8 @@ func (c *Context) DeleteFramebuffer(f Framebuffer) {
 		if !gl.IsFramebuffer(ff) {
 			return nil
 		}
-		// If a framebuffer to be delted is bound, a newly bound framebuffer
-		// will be a default framebuffer.
-		// https://www.khronos.org/opengles/sdk/docs/man/xhtml/glDeleteFramebuffers.xml
 		if c.lastFramebuffer == f {
-			c.lastFramebuffer = ZeroFramebuffer
+			c.lastFramebuffer = invalidFramebuffer
 			c.lastViewportWidth = 0
 			c.lastViewportHeight = 0
 		}

internal/graphics/opengl/context_js.go

@@ -52,6 +52,8 @@ type attribLocation int
 
 type programID int
 
+var invalidFramebuffer = Framebuffer{nil}
+
 func (p Program) id() programID {
 	return programID(p.Get("__ebiten_programId").Int())
 }
@@ -115,19 +117,22 @@ func (c *Context) init() {
 	gl := c.gl
 	// Textures' pixel formats are alpha premultiplied.
 	gl.Enable(gl.BLEND)
-	//gl.BlendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA)
 	c.BlendFunc(CompositeModeSourceOver)
+	f := gl.GetParameter(gl.FRAMEBUFFER_BINDING)
+	c.screenFramebuffer = Framebuffer{f}
 }
 
 func (c *Context) Resume() {
 	c.locationCache = newLocationCache()
-	c.lastFramebuffer = ZeroFramebuffer
+	c.lastFramebuffer = invalidFramebuffer
 	c.lastViewportWidth = 0
 	c.lastViewportHeight = 0
 	c.lastCompositeMode = CompositeModeUnknown
 	gl := c.gl
 	gl.Enable(gl.BLEND)
 	c.BlendFunc(CompositeModeSourceOver)
+	f := gl.GetParameter(gl.FRAMEBUFFER_BINDING)
+	c.screenFramebuffer = Framebuffer{f}
 }
 
 func (c *Context) BlendFunc(mode CompositeMode) {
@@ -252,7 +257,7 @@ func (c *Context) DeleteFramebuffer(f Framebuffer) {
 	// will be a default framebuffer.
 	// https://www.khronos.org/opengles/sdk/docs/man/xhtml/glDeleteFramebuffers.xml
 	if c.lastFramebuffer == f {
-		c.lastFramebuffer = ZeroFramebuffer
+		c.lastFramebuffer = invalidFramebuffer
 		c.lastViewportWidth = 0
 		c.lastViewportHeight = 0
 	}

internal/graphics/opengl/context_mobile.go

@@ -34,6 +34,8 @@ type attribLocation mgl.Attrib
 
 type programID uint32
 
+var invalidFramebuffer = Framebuffer(mgl.Framebuffer{(1 << 32) - 1})
+
 func (p Program) id() programID {
 	return programID(p.Value)
 }
@@ -75,6 +77,8 @@ func NewContext() (*Context, error) {
 		// Textures' pixel formats are alpha premultiplied.
 		c.gl.Enable(mgl.BLEND)
 		c.BlendFunc(CompositeModeSourceOver)
+		f := c.gl.GetInteger(mgl.FRAMEBUFFER_BINDING)
+		c.screenFramebuffer = Framebuffer(mgl.Framebuffer{uint32(f)})
 		close(c.initialized)
 	}()
 	return c, nil
@@ -82,12 +86,14 @@ func NewContext() (*Context, error) {
 
 func (c *Context) Resume() {
 	c.locationCache = newLocationCache()
-	c.lastFramebuffer = ZeroFramebuffer
+	c.lastFramebuffer = invalidFramebuffer
 	c.lastViewportWidth = 0
 	c.lastViewportHeight = 0
 	c.lastCompositeMode = CompositeModeUnknown
 	c.gl.Enable(mgl.BLEND)
 	c.BlendFunc(CompositeModeSourceOver)
+	f := c.gl.GetInteger(mgl.FRAMEBUFFER_BINDING)
+	c.screenFramebuffer = Framebuffer(mgl.Framebuffer{uint32(f)})
 }
 
 func (c *Context) WaitUntilInitializingDone() {
@@ -172,8 +178,8 @@ func (c *Context) TexSubImage2D(p []uint8, width, height int) {
 	gl.TexSubImage2D(mgl.TEXTURE_2D, 0, 0, 0, width, height, mgl.RGBA, mgl.UNSIGNED_BYTE, p)
 }
 
-func (c *Context) BindZeroFramebuffer() {
+func (c *Context) BindScreenFramebuffer() {
-	c.bindFramebuffer(ZeroFramebuffer)
+	c.bindFramebuffer(c.screenFramebuffer)
 }
 
 func (c *Context) NewFramebuffer(texture Texture) (Framebuffer, error) {
@@ -226,7 +232,7 @@ func (c *Context) DeleteFramebuffer(f Framebuffer) {
 	// will be a default framebuffer.
 	// https://www.khronos.org/opengles/sdk/docs/man/xhtml/glDeleteFramebuffers.xml
 	if c.lastFramebuffer == f {
-		c.lastFramebuffer = ZeroFramebuffer
+		c.lastFramebuffer = invalidFramebuffer
 		c.lastViewportWidth = 0
 		c.lastViewportHeight = 0
 	}

internal/ui/ui_glfw.go

@@ -255,7 +255,7 @@ func (u *userInterface) SwapBuffers() error {
 
 func (u *userInterface) swapBuffers() {
 	// The bound framebuffer must be the default one (0) before swapping buffers.
-	u.context.BindZeroFramebuffer()
+	u.context.BindScreenFramebuffer()
 	u.context.RunOnContextThread(func() error {
 		u.window.SwapBuffers()
 		return nil