add example/infinitescroll (#255)

This resolved #254
This commit is contained in:
Martin Lindhe 2016-08-13 16:34:25 +02:00 committed by Hajime Hoshi
parent 3619a796dc
commit 41cc17c4da
2 changed files with 147 additions and 0 deletions

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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.
package main
import (
"fmt"
_ "image/png"
"log"
"math"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
)
const (
screenWidth = 320
screenHeight = 240
)
var (
theViewport = &viewport{}
bgImage *ebiten.Image
repeatedBgImage *ebiten.Image
groundImage *ebiten.Image
)
type viewport struct {
x16 int
y16 int
}
func round(x float64) float64 {
return math.Floor(x + 0.5)
}
func (p *viewport) Move() {
w, h := bgImage.Size()
mx := w * 16
my := h * 16
p.x16 += w / 32
p.y16 += h / 32
for mx <= p.x16 {
p.x16 -= mx
}
for my <= p.y16 {
p.y16 -= my
}
for p.x16 < 0 {
p.x16 += mx
}
for p.y16 < 0 {
p.y16 += my
}
}
func (p *viewport) Position() (int, int) {
return p.x16, p.y16
}
func updateGroundImage(ground *ebiten.Image) error {
if err := ground.Clear(); err != nil {
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 {
return err
}
return nil
}
func drawGroundImage(screen *ebiten.Image, ground *ebiten.Image) error {
op := &ebiten.DrawImageOptions{}
if err := screen.DrawImage(ground, op); err != nil {
return err
}
return nil
}
func update(screen *ebiten.Image) error {
theViewport.Move()
if err := updateGroundImage(groundImage); err != nil {
return err
}
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 {
return err
}
return nil
}
func main() {
var err error
bgImage, _, err = ebitenutil.NewImageFromFile("tile.png", ebiten.FilterNearest)
if err != nil {
log.Fatal(err)
}
w, h := bgImage.Size()
const repeat = 5
repeatedBgImage, err = 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 {
log.Fatal(err)
}
}
}
groundImage, err = 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)
}
}

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