Add example perspective

example/perspective/main.go

@@ -0,0 +1,65 @@
+/*
+Copyright 2014 Hajime Hoshi
+
+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.
+*/
+
+package main
+
+import (
+	"github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/ebitenutil"
+	_ "image/jpeg"
+	"log"
+)
+
+const (
+	screenWidth  = 320
+	screenHeight = 240
+)
+
+type Game struct {
+	gophersTexture *ebiten.Texture
+}
+
+func (g *Game) Update(gr ebiten.GraphicsContext) error {
+	parts := []ebiten.TexturePart{}
+	w, h := g.gophersTexture.Size()
+	for i := 0; i < h; i++ {
+		width := float64(w) + float64(i)*0.75
+		x := float64(h-i) * 0.75 / 2
+		part := ebiten.TexturePart{
+			Dst: ebiten.Rect{x, float64(i), width, 1},
+			Src: ebiten.Rect{0, float64(i), float64(w), 1},
+		}
+		parts = append(parts, part)
+	}
+	maxWidth := float64(w) + float64(h)*0.75
+	geo := ebiten.TranslateGeometry(-maxWidth/2, -float64(h)/2)
+	geo.Concat(ebiten.ScaleGeometry(0.4, 0.4))
+	geo.Concat(ebiten.TranslateGeometry(screenWidth/2, screenHeight/2))
+	gr.Texture(g.gophersTexture).Draw(parts, geo, ebiten.ColorMatrixI())
+	return nil
+}
+
+func main() {
+	g := new(Game)
+	var err error
+	g.gophersTexture, _, err = ebitenutil.NewTextureFromFile("images/gophers.jpg", ebiten.FilterLinear)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := ebiten.Run(g.Update, screenWidth, screenHeight, 2, "Perspective (Ebiten Demo)"); err != nil {
+		log.Fatal(err)
+	}
+}