mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-10 13:07:26 +01:00
112 lines
2.6 KiB
Go
112 lines
2.6 KiB
Go
// Copyright 2016 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build example jsgo
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package main
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import (
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"bytes"
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"fmt"
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"image"
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_ "image/png"
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"log"
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"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/ebitenutil"
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"github.com/hajimehoshi/ebiten/examples/resources/images"
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)
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const (
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screenWidth = 320
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screenHeight = 240
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)
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var (
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bgImage *ebiten.Image
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)
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func init() {
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// Decode image from a byte slice instead of a file so that
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// this example works in any working directory.
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// If you want to use a file, there are some options:
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// 1) Use os.Open and pass the file to the image decoder.
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// This is a very regular way, but doesn't work on browsers.
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// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
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// This works even on browsers.
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// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
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// This also works on browsers.
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img, _, err := image.Decode(bytes.NewReader(images.Tile_png))
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if err != nil {
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log.Fatal(err)
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}
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bgImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
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}
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var (
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theViewport = &viewport{}
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)
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type viewport struct {
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x16 int
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y16 int
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}
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func (p *viewport) Move() {
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w, h := bgImage.Size()
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maxX16 := w * 16
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maxY16 := h * 16
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p.x16 += w / 32
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p.y16 += h / 32
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p.x16 %= maxX16
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p.y16 %= maxY16
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}
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func (p *viewport) Position() (int, int) {
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return p.x16, p.y16
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}
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func update(screen *ebiten.Image) error {
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theViewport.Move()
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if ebiten.IsRunningSlowly() {
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return nil
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}
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x16, y16 := theViewport.Position()
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offsetX, offsetY := float64(-x16)/16, float64(-y16)/16
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// Draw bgImage on the screen repeatedly.
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const repeat = 3
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w, h := bgImage.Size()
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for j := 0; j < repeat; j++ {
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for i := 0; i < repeat; i++ {
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op := &ebiten.DrawImageOptions{}
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op.GeoM.Translate(float64(w*i), float64(h*j))
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op.GeoM.Translate(offsetX, offsetY)
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screen.DrawImage(bgImage, op)
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}
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}
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ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))
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return nil
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}
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func main() {
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if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Infinite Scroll (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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