Bug fix: Creating a render target before running

ebitenutil/texture.go

@@ -22,7 +22,7 @@ import (
 	"os"
 )
 
-func LoadImageAndCreateTexture(path string, filter ebiten.Filter) (ebiten.TextureID, error) {
+func NewTextureIDFromFile(path string, filter ebiten.Filter) (ebiten.TextureID, error) {
 	file, err := os.Open(path)
 	if err != nil {
 		return 0, err

example/image/main.go

@@ -39,7 +39,7 @@ func (g *Game) Update(gr ebiten.GraphicsContext) error {
 
 func main() {
 	g := new(Game)
-	id, err := ebitenutil.LoadImageAndCreateTexture("images/gophers.jpg", ebiten.FilterLinear)
+	id, err := ebitenutil.NewTextureIDFromFile("images/gophers.jpg", ebiten.FilterLinear)
 	if err != nil {
 		log.Fatal(err)
 	}

example/paint/main.go

@@ -23,6 +23,7 @@ import (
 	"image/color"
 	"log"
 	"math"
+	"sync"
 )
 
 const (
@@ -31,6 +32,7 @@ const (
 )
 
 type Game struct {
+	init               sync.Once
 	count              int
 	brushRenderTarget  ebiten.RenderTargetID
 	canvasRenderTarget ebiten.RenderTargetID
@@ -40,27 +42,15 @@ func (g *Game) Update(gr ebiten.GraphicsContext) error {
 	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
 		g.count++
 	}
-	if g.brushRenderTarget.IsNil() {
-		var err error
-		g.brushRenderTarget, err = ebiten.NewRenderTargetID(1, 1, ebiten.FilterNearest)
-		if err != nil {
-			return err
-		}
-
+	g.init.Do(func() {
 		gr.PushRenderTarget(g.brushRenderTarget)
 		gr.Fill(0xff, 0xff, 0xff)
 		gr.PopRenderTarget()
-	}
-	if g.canvasRenderTarget.IsNil() {
-		var err error
-		g.canvasRenderTarget, err = ebiten.NewRenderTargetID(screenWidth, screenHeight, ebiten.FilterNearest)
-		if err != nil {
-			return err
-		}
 		gr.PushRenderTarget(g.canvasRenderTarget)
 		gr.Fill(0xff, 0xff, 0xff)
 		gr.PopRenderTarget()
-	}
+	})
+
 	mx, my := ebiten.CursorPosition()
 
 	if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
@@ -81,6 +71,15 @@ func (g *Game) Update(gr ebiten.GraphicsContext) error {
 
 func main() {
 	g := new(Game)
+	var err error
+	g.brushRenderTarget, err = ebiten.NewRenderTargetID(1, 1, ebiten.FilterNearest)
+	if err != nil {
+		log.Fatal(err)
+	}
+	g.canvasRenderTarget, err = ebiten.NewRenderTargetID(screenWidth, screenHeight, ebiten.FilterNearest)
+	if err != nil {
+		log.Fatal(err)
+	}
 	if err := ebiten.Run(g.Update, screenWidth, screenHeight, 2, "Paint (Ebiten Demo)"); err != nil {
 		log.Fatal(err)
 	}

graphicscontext.go

@@ -22,10 +22,6 @@ import (
 )
 
 func newGraphicsContext(screenWidth, screenHeight, screenScale int) (*graphicsContext, error) {
-	gl.Init()
-	gl.Enable(gl.TEXTURE_2D)
-	gl.Enable(gl.BLEND)
-
 	// The defualt framebuffer should be 0.
 	r := opengl.NewRenderTarget(screenWidth*screenScale, screenHeight*screenScale, true)
 

ui.go

@@ -18,6 +18,7 @@ package ebiten
 
 import (
 	"fmt"
+	"github.com/go-gl/gl"
 	glfw "github.com/go-gl/glfw3"
 	"image"
 	"runtime"
@@ -47,6 +48,11 @@ func init() {
 		funcs:  make(chan func()),
 	}
 	currentUI.run()
+	currentUI.use(func() {
+		gl.Init()
+		gl.Enable(gl.TEXTURE_2D)
+		gl.Enable(gl.BLEND)
+	})
 }
 
 type ui struct {