docs: Update example pages

docs/examples/alphablending.html

@@ -79,17 +79,13 @@ func update(screen *ebiten.Image) error {
                 diff = float64(480-count) * 0.2
         }
 
-        if err := screen.Fill(color.NRGBA{0x00, 0x00, 0x80, 0xff}); err != nil {
+        screen.Fill(color.NRGBA{0x00, 0x00, 0x80, 0xff})
-                return err
-        }
         op := &ebiten.DrawImageOptions{}
         op.ColorM.Scale(1.0, 1.0, 1.0, 0.5)
         op.ImageParts = &imageParts{
                 diff: diff,
         }
-        if err := screen.DrawImage(ebitenImage, op); err != nil {
+        screen.DrawImage(ebitenImage, op)
-                return err
-        }
         return nil
 }
 

docs/examples/audio.html

@@ -115,9 +115,9 @@ func (p *Player) updateSE() error {
         return sePlayer.Play()
 }
 
-func (p *Player) updateVolume() error {
+func (p *Player) updateVolume() {
         if p.audioPlayer == nil {
-                return nil
+                return
         }
         if ebiten.IsKeyPressed(ebiten.KeyZ) {
                 volume128--
@@ -132,7 +132,6 @@ func (p *Player) updateVolume() error {
                 volume128 = 128
         }
         p.audioPlayer.SetVolume(float64(volume128) / 128)
-        return nil
 }
 
 func (p *Player) updatePlayPause() error {
@@ -153,29 +152,29 @@ func (p *Player) updatePlayPause() error {
         return p.audioPlayer.Play()
 }
 
-func (p *Player) updateBar() error {
+func (p *Player) updateBar() {
         if p.audioPlayer == nil {
-                return nil
+                return
         }
         if p.seekedCh != nil {
-                return nil
+                return
         }
         if !ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
                 mouseButtonState[ebiten.MouseButtonLeft] = 0
-                return nil
+                return
         }
         mouseButtonState[ebiten.MouseButtonLeft]++
         if mouseButtonState[ebiten.MouseButtonLeft] != 1 {
-                return nil
+                return
         }
         x, y := ebiten.CursorPosition()
         bx, by, bw, bh := playerBarRect()
         const padding = 4
         if y < by-padding || by+bh+padding <= y {
-                return nil
+                return
         }
         if x < bx || bx+bw <= x {
-                return nil
+                return
         }
         pos := time.Duration(x-bx) * p.total / time.Duration(bw)
         p.seekedCh = make(chan error, 1)
@@ -183,7 +182,6 @@ func (p *Player) updateBar() error {
                 // This can't be done parallely! !?!?
                 p.seekedCh <- p.audioPlayer.Seek(pos)
         }()
-        return nil
 }
 
 func (p *Player) close() error {
@@ -204,26 +202,20 @@ func update(screen *ebiten.Image) error {
                 }
         }
         if musicPlayer != nil {
-                if err := musicPlayer.updateBar(); err != nil {
+                musicPlayer.updateBar()
-                        return err
-                }
                 if err := musicPlayer.updatePlayPause(); err != nil {
                         return err
                 }
                 if err := musicPlayer.updateSE(); err != nil {
                         return err
                 }
-                if err := musicPlayer.updateVolume(); err != nil {
+                musicPlayer.updateVolume()
-                        return err
-                }
         }
 
         op := &ebiten.DrawImageOptions{}
         x, y, w, h := playerBarRect()
         op.GeoM.Translate(float64(x), float64(y))
-        if err := screen.DrawImage(playerBarImage, op); err != nil {
+        screen.DrawImage(playerBarImage, op)
-                return err
-        }
         currentTimeStr := "00:00"
         if musicPlayer != nil {
                 c := musicPlayer.audioPlayer.Current()
@@ -239,9 +231,7 @@ func update(screen *ebiten.Image) error {
                 cy := y - (ch-h)/2
                 op := &ebiten.DrawImageOptions{}
                 op.GeoM.Translate(float64(cx), float64(cy))
-                if err := screen.DrawImage(playerCurrentImage, op); err != nil {
+                screen.DrawImage(playerCurrentImage, op)
-                        return err
-                }
         }
 
         msg := fmt.Sprintf(`FPS: %0.2f
@@ -263,9 +253,7 @@ Press Z or X to change volume of the music
                         msg += "\nSeeking..."
                 }
         }
-        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
+        ebitenutil.DebugPrint(screen, msg)
-                return err
-        }
         if err := audioContext.Update(); err != nil {
                 return err
         }

docs/examples/font.html

@@ -97,22 +97,17 @@ func parseFont() error {
                 d.DrawString(s)
                 y += size
         }
-        return textImage.ReplacePixels(dst.Pix)
+        textImage.ReplacePixels(dst.Pix)
+        return nil
 }
 
 func update(screen *ebiten.Image) error {
-        if err := screen.DrawImage(textImage, &ebiten.DrawImageOptions{}); err != nil {
+        screen.DrawImage(textImage, &ebiten.DrawImageOptions{})
-                return err
-        }
         return nil
 }
 
 func main() {
-        var err error
+        textImage, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        textImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
         if err := parseFont(); err != nil {
                 log.Fatal(err)
         }

docs/examples/gamepad.html

@@ -69,9 +69,7 @@ func update(screen *ebiten.Image) error {
   Pressed Buttons: {{.Buttons}}`
         str = strings.Replace(str, "{{.Axes}}", strings.Join(axes, "\n    "), -1)
         str = strings.Replace(str, "{{.Buttons}}", strings.Join(pressedButtons, ", "), -1)
-        if err := ebitenutil.DebugPrint(screen, str); err != nil {
+        ebitenutil.DebugPrint(screen, str)
-                return err
-        }
         return nil
 }
 

docs/examples/hsv.html

@@ -94,16 +94,12 @@ func update(screen *ebiten.Image) error {
         saturation := float64(saturationInt) / 128
         value := float64(valueInt) / 128
         op.ColorM.ChangeHSV(hue, saturation, value)
-        if err := screen.DrawImage(gophersImage, op); err != nil {
+        screen.DrawImage(gophersImage, op)
-                return err
-        }
 
         msg := fmt.Sprintf(`Hue:        %0.2f [Q][W]
 Saturation: %0.2f [A][S]
 Value:      %0.2f [Z][X]`, hue, saturation, value)
-        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
+        ebitenutil.DebugPrint(screen, msg)
-                return err
-        }
         return nil
 }
 

docs/examples/hue.html

@@ -54,9 +54,7 @@ func update(screen *ebiten.Image) error {
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Translate(float64(screenWidth-w)/2, float64(screenHeight-h)/2)
         op.ColorM.RotateHue(float64(count%360) * 2 * math.Pi / 360)
-        if err := screen.DrawImage(gophersImage, op); err != nil {
+        screen.DrawImage(gophersImage, op)
-                return err
-        }
         return nil
 }
 

docs/examples/infinitescroll.html

@@ -86,41 +86,27 @@ func (p *viewport) Position() (int, int) {
         return p.x16, p.y16
 }
 
-func updateGroundImage(ground *ebiten.Image) error {
+func updateGroundImage(ground *ebiten.Image) {
-        if err := ground.Clear(); err != nil {
+        ground.Clear()
-                return err
-        }
         x16, y16 := theViewport.Position()
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Translate(float64(-x16)/16, float64(-y16)/16)
-        if err := ground.DrawImage(repeatedBgImage, op); err != nil {
+        ground.DrawImage(repeatedBgImage, op)
-                return err
-        }
-        return nil
 }
 
-func drawGroundImage(screen *ebiten.Image, ground *ebiten.Image) error {
+func drawGroundImage(screen *ebiten.Image, ground *ebiten.Image) {
         op := &ebiten.DrawImageOptions{}
-        if err := screen.DrawImage(ground, op); err != nil {
+        screen.DrawImage(ground, op)
-                return err
-        }
-        return nil
 }
 
 func update(screen *ebiten.Image) error {
         theViewport.Move()
 
-        if err := updateGroundImage(groundImage); err != nil {
+        updateGroundImage(groundImage)
-                return err
+        drawGroundImage(screen, groundImage)
-        }
-        if err := drawGroundImage(screen, groundImage); err != nil {
-                return err
-        }
 
         msg := fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS())
-        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
+        ebitenutil.DebugPrint(screen, msg)
-                return err
-        }
         return nil
 }
 
@@ -132,23 +118,15 @@ func main() {
         }
         w, h := bgImage.Size()
         const repeat = 5
-        repeatedBgImage, err = ebiten.NewImage(w*repeat, h*repeat, ebiten.FilterNearest)
+        repeatedBgImage, _ = ebiten.NewImage(w*repeat, h*repeat, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
         for j := 0; j < repeat; j++ {
                 for i := 0; i < repeat; i++ {
                         op := &ebiten.DrawImageOptions{}
                         op.GeoM.Translate(float64(w*i), float64(h*j))
-                        if err := repeatedBgImage.DrawImage(bgImage, op); err != nil {
+                        repeatedBgImage.DrawImage(bgImage, op)
-                                log.Fatal(err)
-                        }
                 }
         }
-        groundImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
+        groundImage, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
 
         if err := ebiten.Run(update, screenWidth, screenHeight, 2, "infinite scroll"); err != nil {
                 log.Fatal(err)

docs/examples/keyboard.html

@@ -99,9 +99,7 @@ func update(screen *ebiten.Image) error {
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Translate(offsetX, offsetY)
         op.ColorM.Scale(0.5, 0.5, 0.5, 1)
-        if err := screen.DrawImage(keyboardImage, op); err != nil {
+        screen.DrawImage(keyboardImage, op)
-                return err
-        }
 
         pressed := []string{}
         for i := 0; i <= 9; i++ {
@@ -129,9 +127,7 @@ func update(screen *ebiten.Image) error {
                 ImageParts: pressedKeysParts(pressed),
         }
         op.GeoM.Translate(offsetX, offsetY)
-        if err := screen.DrawImage(keyboardImage, op); err != nil {
+        screen.DrawImage(keyboardImage, op)
-                return err
-        }
 
         return nil
 }

docs/examples/life.html

@@ -185,9 +185,7 @@ var (
 func update(screen *ebiten.Image) error {
         world.Progress()
         world.DrawImage(noiseImage)
-        if err := screen.ReplacePixels(noiseImage.Pix); err != nil {
+        screen.ReplacePixels(noiseImage.Pix)
-                return err
-        }
         return nil
 }
 

docs/examples/masking.html

@@ -78,31 +78,19 @@ func update(screen *ebiten.Image) error {
                 spotLightVY = -spotLightVY
         }
 
-        if err := maskImage.Clear(); err != nil {
+        maskImage.Clear()
-                return err
-        }
 
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Translate(float64(spotLightX), float64(spotLightY))
-        if err := maskImage.DrawImage(spotLightImage, op); err != nil {
+        maskImage.DrawImage(spotLightImage, op)
-                return err
-        }
 
         op = &ebiten.DrawImageOptions{}
         op.CompositeMode = ebiten.CompositeModeSourceOut
-        if err := maskImage.DrawImage(fiveyearsImage, op); err != nil {
+        maskImage.DrawImage(fiveyearsImage, op)
-                return err
-        }
 
-        if err := screen.Fill(color.RGBA{0x00, 0x00, 0x80, 0xff}); err != nil {
+        screen.Fill(color.RGBA{0x00, 0x00, 0x80, 0xff})
-                return err
+        screen.DrawImage(gophersImage, &ebiten.DrawImageOptions{})
-        }
+        screen.DrawImage(maskImage, &ebiten.DrawImageOptions{})
-        if err := screen.DrawImage(gophersImage, &ebiten.DrawImageOptions{}); err != nil {
-                return err
-        }
-        if err := screen.DrawImage(maskImage, &ebiten.DrawImageOptions{}); err != nil {
-                return err
-        }
 
         return nil
 }
@@ -131,10 +119,7 @@ func main() {
         if err != nil {
                 log.Fatal(err)
         }
-        maskImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
+        maskImage, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
 
         as := image.Point{128, 128}
         a := image.NewAlpha(image.Rectangle{image.ZP, as})
@@ -146,10 +131,7 @@ func main() {
                         a.SetAlpha(i, j, color.Alpha{b})
                 }
         }
-        spotLightImage, err = ebiten.NewImageFromImage(a, ebiten.FilterNearest)
+        spotLightImage, _ = ebiten.NewImageFromImage(a, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
         if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Masking (Ebiten Demo)"); err != nil {
                 log.Fatal(err)
         }

docs/examples/mosaic.html

@@ -52,14 +52,10 @@ var (
 func update(screen *ebiten.Image) error {
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Scale(1.0/mosaicRatio, 1.0/mosaicRatio)
-        if err := gophersRenderTarget.DrawImage(gophersImage, op); err != nil {
+        gophersRenderTarget.DrawImage(gophersImage, op)
-                return err
-        }
         op = &ebiten.DrawImageOptions{}
         op.GeoM.Scale(mosaicRatio, mosaicRatio)
-        if err := screen.DrawImage(gophersRenderTarget, op); err != nil {
+        screen.DrawImage(gophersRenderTarget, op)
-                return err
-        }
         return nil
 }
 
@@ -70,10 +66,7 @@ func main() {
                 log.Fatal(err)
         }
         w, h := gophersImage.Size()
-        gophersRenderTarget, err = ebiten.NewImage(w/mosaicRatio, h/mosaicRatio, ebiten.FilterNearest)
+        gophersRenderTarget, _ = ebiten.NewImage(w/mosaicRatio, h/mosaicRatio, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
         if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Mosaic (Ebiten Demo)"); err != nil {
                 log.Fatal(err)
         }

docs/examples/noise.html

@@ -71,12 +71,8 @@ func update(screen *ebiten.Image) error {
                 noiseImage.Pix[4*i+2] = uint8(x >> 8)
                 noiseImage.Pix[4*i+3] = 0xff
         }
-        if err := screen.ReplacePixels(noiseImage.Pix); err != nil {
+        screen.ReplacePixels(noiseImage.Pix)
-                return err
+        ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %f", ebiten.CurrentFPS()))
-        }
-        if err := ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %f", ebiten.CurrentFPS())); err != nil {
-                return err
-        }
         return nil
 }
 

docs/examples/paint.html

@@ -51,55 +51,43 @@ var (
         canvasImage *ebiten.Image
 )
 
-func paint(screen *ebiten.Image, x, y int) error {
+func paint(screen *ebiten.Image, x, y int) {
         op := &ebiten.DrawImageOptions{}
         op.GeoM.Translate(float64(x), float64(y))
         op.ColorM.Scale(1.0, 0.50, 0.125, 1.0)
         theta := 2.0 * math.Pi * float64(count%60) / ebiten.FPS
         op.ColorM.RotateHue(theta)
-        if err := canvasImage.DrawImage(brushImage, op); err != nil {
+        canvasImage.DrawImage(brushImage, op)
-                return err
-        }
-        return nil
 }
 
 func update(screen *ebiten.Image) error {
         drawn := false
         mx, my := ebiten.CursorPosition()
         if ebiten.IsMouseButtonPressed(ebiten.MouseButtonLeft) {
-                if err := paint(screen, mx, my); err != nil {
+                paint(screen, mx, my)
-                        return err
-                }
                 drawn = true
         }
         for _, t := range ebiten.Touches() {
                 x, y := t.Position()
-                if err := paint(screen, x, y); err != nil {
+                paint(screen, x, y)
-                        return err
-                }
                 drawn = true
         }
         if drawn {
                 count++
         }
 
-        if err := screen.DrawImage(canvasImage, nil); err != nil {
+        screen.DrawImage(canvasImage, nil)
-                return err
-        }
 
         msg := fmt.Sprintf("(%d, %d)", mx, my)
         for _, t := range ebiten.Touches() {
                 x, y := t.Position()
                 msg += fmt.Sprintf("\n(%d, %d) touch %d", x, y, t.ID())
         }
-        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
+        ebitenutil.DebugPrint(screen, msg)
-                return err
-        }
         return nil
 }
 
 func main() {
-        var err error
         const a0, a1, a2 = 0x40, 0xc0, 0xff
         pixels := []uint8{
                 a0, a1, a1, a0,
@@ -107,22 +95,14 @@ func main() {
                 a1, a2, a2, a1,
                 a0, a1, a1, a0,
         }
-        brushImage, err = ebiten.NewImageFromImage(&image.Alpha{
+        brushImage, _ = ebiten.NewImageFromImage(&image.Alpha{
                 Pix:    pixels,
                 Stride: 4,
                 Rect:   image.Rect(0, 0, 4, 4),
         }, ebiten.FilterNearest)
-        if err != nil {
-                log.Fatal(err)
-        }
 
-        canvasImage, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
+        canvasImage, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        if err != nil {
+        canvasImage.Fill(color.White)
-                log.Fatal(err)
-        }
-        if err := canvasImage.Fill(color.White); err != nil {
-                log.Fatal(err)
-        }
 
         if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Paint (Ebiten Demo)"); err != nil {
                 log.Fatal(err)

docs/examples/perspective.html

@@ -75,9 +75,7 @@ func update(screen *ebiten.Image) error {
         maxWidth := float64(w) + float64(h)*0.75
         op.GeoM.Translate(-maxWidth/2, -float64(h)/2)
         op.GeoM.Translate(screenWidth/2, screenHeight/2)
-        if err := screen.DrawImage(gophersImage, op); err != nil {
+        screen.DrawImage(gophersImage, op)
-                return err
-        }
         return nil
 }
 

docs/examples/piano.html

@@ -175,18 +175,9 @@ var (
 )
 
 func init() {
-        var err error
+        imageEmpty, _ := ebiten.NewImage(16, 16, ebiten.FilterNearest)
-        imageEmpty, err := ebiten.NewImage(16, 16, ebiten.FilterNearest)
+        imageEmpty.Fill(color.White)
-        if err != nil {
+        imagePiano, _ = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-                panic(err)
-        }
-        if err := imageEmpty.Fill(color.White); err != nil {
-                panic(err)
-        }
-        imagePiano, err = ebiten.NewImage(screenWidth, screenHeight, ebiten.FilterNearest)
-        if err != nil {
-                panic(err)
-        }
         whiteKeys := []string{"A", "S", "D", "F", "G", "H", "J", "K", "L"}
         width := 24
         y := 48
@@ -198,12 +189,8 @@ func init() {
                 op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
                 op.GeoM.Translate(float64(x), float64(y))
                 op.ColorM.Scale(1, 1, 1, 1)
-                if err := imagePiano.DrawImage(imageEmpty, op); err != nil {
+                imagePiano.DrawImage(imageEmpty, op)
-                        panic(err)
+                common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.Black)
-                }
-                if err := common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.Black); err != nil {
-                        panic(err)
-                }
         }
 
         blackKeys := []string{"Q", "W", "", "R", "T", "", "U", "I", "O"}
@@ -218,12 +205,8 @@ func init() {
                 op.GeoM.Scale(float64(width-1)/float64(w), float64(height)/float64(h))
                 op.GeoM.Translate(float64(x), float64(y))
                 op.ColorM.Scale(0, 0, 0, 1)
-                if err := imagePiano.DrawImage(imageEmpty, op); err != nil {
+                imagePiano.DrawImage(imageEmpty, op)
-                        panic(err)
+                common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.White)
-                }
-                if err := common.ArcadeFont.DrawText(imagePiano, k, x+8, y+height-16, 1, color.White); err != nil {
-                        panic(err)
-                }
         }
 }
 
@@ -238,16 +221,10 @@ func update(screen *ebiten.Image) error {
                 }
         }
 
-        if err := screen.Fill(color.RGBA{0x80, 0x80, 0xc0, 0xff}); err != nil {
+        screen.Fill(color.RGBA{0x80, 0x80, 0xc0, 0xff})
-                return err
+        screen.DrawImage(imagePiano, nil)
-        }
-        if err := screen.DrawImage(imagePiano, nil); err != nil {
-                return err
-        }
 
-        if err := ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS())); err != nil {
+        ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
-                return err
-        }
 
         if err := audioContext.Update(); err != nil {
                 return err

docs/examples/rotate.html

@@ -55,9 +55,7 @@ func update(screen *ebiten.Image) error {
         op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
         op.GeoM.Rotate(float64(count%360) * 2 * math.Pi / 360)
         op.GeoM.Translate(screenWidth/2, screenHeight/2)
-        if err := screen.DrawImage(gophersImage, op); err != nil {
+        screen.DrawImage(gophersImage, op)
-                return err
-        }
         return nil
 }
 

docs/examples/sprites.html

@@ -137,15 +137,11 @@ func update(screen *ebiten.Image) error {
                 ImageParts: sprites,
         }
         op.ColorM.Scale(1.0, 1.0, 1.0, 0.5)
-        if err := screen.DrawImage(ebitenImage, op); err != nil {
+        screen.DrawImage(ebitenImage, op)
-                return err
-        }
         msg := fmt.Sprintf(`FPS: %0.2f
 Num of sprites: %d
 Press <- or -> to change the number of sprites`, ebiten.CurrentFPS(), sprites.Len())
-        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
+        ebitenutil.DebugPrint(screen, msg)
-                return err
-        }
         return nil
 }