Added simple platformer example (#448)

examples/_resources/images/license.md

@@ -31,6 +31,20 @@ http://opengameart.org/node/8016
 CC0 1.0
 ```
 
+## platformer/right.png platformer/left.png platformer/mainchar.png
+
+```
+The Go gopher was designed by Renee French. (http://reneefrench.blogspot.com/)
+The design is licensed under the Creative Commons 3.0 Attributions license.
+Read this article for more details: https://blog.golang.org/gopher
+```
+
+## platformer/background.png
+
+```
+https://corvussg.itch.io/2d-game-backgrounds
+```
+
 ## Other image files
 
 ```

examples/platformer/main.go

@@ -0,0 +1,120 @@
+// Copyright 2017 The Ebiten 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.
+
+// +build example
+
+package main
+
+import (
+	"fmt"
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+)
+
+const (
+	// Settings
+	width           = 1024
+	height          = 512
+	fullscreen      = false
+	runinbackground = true
+)
+
+var (
+	loadedSprite    *ebiten.Image
+	leftSprite      *ebiten.Image
+	rightSprite     *ebiten.Image
+	idleSprite      *ebiten.Image
+	backgroundImage *ebiten.Image
+	err             error
+
+	isFirstFrame bool = true
+
+	backgroundOptions = &ebiten.DrawImageOptions{}
+	charSpriteOptions = &ebiten.DrawImageOptions{}
+)
+
+func update(screen *ebiten.Image) error {
+	// Draws Background Image
+	screen.DrawImage(backgroundImage, backgroundOptions)
+
+	// Resets
+	charX := 0.0
+	charY := 0.0
+
+	if isFirstFrame == true {
+		charY += 380
+		charX += 50
+		isFirstFrame = false
+	}
+
+	// Controls
+	if ebiten.IsKeyPressed(ebiten.KeyA) {
+		// Selects preloaded sprite
+		loadedSprite = leftSprite
+		// Moves character 3px right
+		charX -= 3.0
+	} else if ebiten.IsKeyPressed(ebiten.KeyD) {
+		// Selects preloaded sprite
+		loadedSprite = rightSprite
+		// Moves character 3px left
+		charX += +3.0
+	} else {
+		loadedSprite = idleSprite
+	}
+
+	// Change gopher's position
+	charSpriteOptions.GeoM.Translate(charX, charY)
+
+	// FPS counter
+	fps := fmt.Sprintf("FPS: %f", ebiten.CurrentFPS())
+	ebitenutil.DebugPrint(screen, fps)
+
+	// Draws selected sprite image
+	screen.DrawImage(loadedSprite, charSpriteOptions)
+
+	return nil
+}
+
+func main() {
+	// Settings for images
+	backgroundOptions.GeoM.Scale(0.5, 0.5)
+	backgroundOptions.GeoM.Translate(0, 0)
+	charSpriteOptions.GeoM.Scale(0.5, 0.5)
+
+	// Preload images
+	rightSprite, _, err = ebitenutil.NewImageFromFile("_resources/images/platformer/right.png", ebiten.FilterNearest)
+	if err != nil {
+		panic(err)
+	}
+	leftSprite, _, err = ebitenutil.NewImageFromFile("_resources/images/platformer/left.png", ebiten.FilterNearest)
+	if err != nil {
+		panic(err)
+	}
+	idleSprite, _, err = ebitenutil.NewImageFromFile("_resources/images/platformer/mainchar.png", ebiten.FilterNearest)
+	if err != nil {
+		panic(err)
+	}
+	backgroundImage, _, err = ebitenutil.NewImageFromFile("_resources/images/platformer/background.png", ebiten.FilterNearest)
+	if err != nil {
+		panic(err)
+	}
+
+	ebiten.SetRunnableInBackground(runinbackground)
+	ebiten.SetFullscreen(fullscreen)
+
+	// Starts the program
+	if err := ebiten.Run(update, width, height, 1, "Platformer (Ebiten Demo)"); err != nil {
+		panic(err)
+	}
+}