ebiten/examples/infinitescroll/main.go

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// Copyright 2016 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"
_ "image/png"
"log"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
)
const (
screenWidth = 320
screenHeight = 240
)
var (
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bgImage *ebiten.Image
)
func init() {
var err error
bgImage, _, err = ebitenutil.NewImageFromFile("_resources/images/tile.png", ebiten.FilterNearest)
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if err != nil {
log.Fatal(err)
}
}
var (
theViewport = &viewport{}
)
type viewport struct {
x16 int
y16 int
}
func (p *viewport) Move() {
w, h := bgImage.Size()
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maxX16 := w * 16
maxY16 := h * 16
p.x16 += w / 32
p.y16 += h / 32
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p.x16 %= maxX16
p.y16 %= maxY16
}
func (p *viewport) Position() (int, int) {
return p.x16, p.y16
}
func update(screen *ebiten.Image) error {
theViewport.Move()
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if ebiten.IsRunningSlowly() {
return nil
}
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x16, y16 := theViewport.Position()
offsetX, offsetY := float64(-x16)/16, float64(-y16)/16
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// Draw bgImage on the screen repeatedly.
const repeat = 3
w, h := bgImage.Size()
for j := 0; j < repeat; j++ {
for i := 0; i < repeat; i++ {
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(w*i), float64(h*j))
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op.GeoM.Translate(offsetX, offsetY)
screen.DrawImage(bgImage, op)
}
}
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ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
return nil
}
func main() {
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Infinite Scroll (Ebiten Demo)"); err != nil {
log.Fatal(err)
}
}