tmp

examples/skipdraw/main.go

@@ -0,0 +1,90 @@
+// Copyright 2022 The Ebitengine Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build example
+// +build example
+
+package main
+
+import (
+	"bytes"
+	"image"
+	_ "image/jpeg"
+	"log"
+	"math"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
+	"github.com/hajimehoshi/ebiten/v2/inpututil"
+)
+
+const (
+	screenWidth  = 640
+	screenHeight = 480
+)
+
+var (
+	gophersImage *ebiten.Image
+)
+
+type Game struct {
+	count int
+}
+
+func (g *Game) Update() error {
+	g.count++
+	if len(inpututil.AppendPressedKeys(nil)) > 0 {
+		return nil
+	}
+	ebiten.SkipDraw()
+	return nil
+}
+
+func (g *Game) Draw(screen *ebiten.Image) {
+	w, h := gophersImage.Size()
+	op := &ebiten.DrawImageOptions{}
+
+	// Move the image's center to the screen's upper-left corner.
+	// This is a preparation for rotating. When geometry matrices are applied,
+	// the origin point is the upper-left corner.
+	op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
+
+	// Rotate the image. As a result, the anchor point of this rotate is
+	// the center of the image.
+	op.GeoM.Rotate(float64(g.count%360) * 2 * math.Pi / 360)
+
+	// Move the image to the screen's center.
+	op.GeoM.Translate(screenWidth/2, screenHeight/2)
+
+	screen.DrawImage(gophersImage, op)
+}
+
+func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return screenWidth, screenHeight
+}
+
+func main() {
+	// Decode an image from the image file's byte slice.
+	img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
+	if err != nil {
+		log.Fatal(err)
+	}
+	gophersImage = ebiten.NewImageFromImage(img)
+
+	ebiten.SetWindowSize(screenWidth, screenHeight)
+	ebiten.SetWindowTitle("Rotate (Ebitengine Demo)")
+	if err := ebiten.RunGame(&Game{}); err != nil {
+		log.Fatal(err)
+	}
+}

internal/graphicscommand/command.go

@@ -168,7 +168,8 @@ func (q *commandQueue) Flush(graphicsDriver graphicsdriver.Graphics, endFrame bo
 
 // flush must be called the main thread.
 func (q *commandQueue) flush(graphicsDriver graphicsdriver.Graphics, endFrame bool) (err error) {
-	if len(q.commands) == 0 {
+	// If endFrame is true, Begin/End should be called to ensure the framebuffer is swapped.
+	if len(q.commands) == 0 && !endFrame {
 		return nil
 	}
 

internal/graphicsdriver/directx/graphics_windows.go

@@ -770,7 +770,7 @@ func (g *Graphics) End(present bool) error {
 
 	g.pipelineStates.resetConstantBuffers(g.frameIndex)
 
-	if present {
+	if present && g.swapChain != nil {
 		if microsoftgdk.IsXbox() {
 			if err := g.presentXbox(); err != nil {
 				return err

internal/graphicsdriver/metal/graphics_darwin.go

@@ -199,11 +199,15 @@ func (g *Graphics) SetVertices(vertices []float32, indices []uint16) error {
 }
 
 func (g *Graphics) flushIfNeeded(present bool) {
-	if g.cb == (mtl.CommandBuffer{}) {
+	if g.cb == (mtl.CommandBuffer{}) && !present {
 		return
 	}
 	g.flushRenderCommandEncoderIfNeeded()
 
+	if g.screenDrawable == (ca.MetalDrawable{}) {
+		g.screenDrawable = g.view.nextDrawable()
+	}
+
 	if !g.view.presentsWithTransaction() && present && g.screenDrawable != (ca.MetalDrawable{}) {
 		g.cb.PresentDrawable(g.screenDrawable)
 	}

internal/ui/context.go

@@ -142,8 +142,16 @@ func (c *context) updateFrameImpl(graphicsDriver graphicsdriver.Graphics, update
 	}
 
 	// Draw the game.
-	if err := c.drawGame(graphicsDriver); err != nil {
-		return err
+	drawSkipped := theGlobalState.drawSkipped()
+	defer func() {
+		if updateCount > 0 {
+			theGlobalState.resetDrawSkipped()
+		}
+	}()
+	if !drawSkipped {
+		if err := c.drawGame(graphicsDriver); err != nil {
+			return err
+		}
 	}
 
 	return nil

internal/ui/globalstate.go

@@ -32,6 +32,7 @@ type globalState struct {
 	fpsMode_                   int32
 	isScreenClearedEveryFrame_ int32
 	graphicsLibrary_           int32
+	drawSkipped_               int32
 }
 
 func (g *globalState) error() error {
@@ -76,6 +77,18 @@ func (g *globalState) graphicsLibrary() GraphicsLibrary {
 	return GraphicsLibrary(atomic.LoadInt32(&g.graphicsLibrary_))
 }
 
+func (g *globalState) skipDraw() {
+	atomic.StoreInt32(&g.drawSkipped_, 1)
+}
+
+func (g *globalState) resetDrawSkipped() {
+	atomic.StoreInt32(&g.drawSkipped_, 0)
+}
+
+func (g *globalState) drawSkipped() bool {
+	return atomic.LoadInt32(&g.drawSkipped_) != 0
+}
+
 func FPSMode() FPSModeType {
 	return theGlobalState.fpsMode()
 }
@@ -96,3 +109,7 @@ func SetScreenClearedEveryFrame(cleared bool) {
 func GetGraphicsLibrary() GraphicsLibrary {
 	return theGlobalState.graphicsLibrary()
 }
+
+func SkipDraw() {
+	theGlobalState.skipDraw()
+}

run.go

@@ -537,3 +537,7 @@ func SetScreenTransparent(transparent bool) {
 func SetInitFocused(focused bool) {
 	ui.Get().SetInitFocused(focused)
 }
+
+func SkipDraw() {
+	ui.SkipDraw()
+}