mirror of
https://github.com/hajimehoshi/ebiten.git
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83 lines
2.0 KiB
Go
83 lines
2.0 KiB
Go
// Copyright 2014 Hajime Hoshi
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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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package main
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import (
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"bytes"
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"image"
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_ "image/jpeg"
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"log"
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"math"
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"github.com/hajimehoshi/ebiten/v2"
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"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
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)
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const (
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screenWidth = 640
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screenHeight = 480
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)
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var (
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gophersImage *ebiten.Image
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)
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type Game struct {
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count int
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}
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func (g *Game) Update() error {
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g.count++
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return nil
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}
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func (g *Game) Draw(screen *ebiten.Image) {
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s := gophersImage.Bounds().Size()
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op := &ebiten.DrawImageOptions{}
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// Move the image's center to the screen's upper-left corner.
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// This is a preparation for rotating. When geometry matrices are applied,
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// the origin point is the upper-left corner.
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op.GeoM.Translate(-float64(s.X)/2, -float64(s.Y)/2)
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// Rotate the image. As a result, the anchor point of this rotate is
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// the center of the image.
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op.GeoM.Rotate(float64(g.count%360) * 2 * math.Pi / 360)
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// Move the image to the screen's center.
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op.GeoM.Translate(screenWidth/2, screenHeight/2)
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screen.DrawImage(gophersImage, op)
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}
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func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
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return screenWidth, screenHeight
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}
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func main() {
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// Decode an image from the image file's byte slice.
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img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
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if err != nil {
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log.Fatal(err)
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}
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gophersImage = ebiten.NewImageFromImage(img)
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ebiten.SetWindowSize(screenWidth, screenHeight)
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ebiten.SetWindowTitle("Rotate (Ebitengine Demo)")
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if err := ebiten.RunGame(&Game{}); err != nil {
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log.Fatal(err)
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}
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}
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