ebiten/examples/blur/main.go

89 lines
2.5 KiB
Go

// Copyright 2018 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.
//go:build example
// +build example
package main
import (
"bytes"
"image"
_ "image/jpeg"
"log"
"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
)
const (
screenWidth = 640
screenHeight = 480
)
var (
gophersImage *ebiten.Image
)
type Game struct{}
func (g *Game) Update() error {
return nil
}
func (g *Game) Draw(screen *ebiten.Image) {
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(0, 0)
screen.DrawImage(gophersImage, op)
// Box blur (7x7)
// https://en.wikipedia.org/wiki/Box_blur
for j := -3; j <= 3; j++ {
for i := -3; i <= 3; i++ {
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(float64(i), 244+float64(j))
// Alpha scale should be 1.0/49.0, but accumulating 1/49 49 times doesn't reach to 1, because
// the final color is affected by the destination alpha when CompositeModeSourceOver is used.
// This composite mode is the default mode. See how this is calculated at the doc:
// https://pkg.go.dev/github.com/hajimehoshi/ebiten/v2#CompositeMode
//
// Use a higher value than 1.0/49.0. Here, 1.0/25.0 here to get a reasonable result.
op.ColorM.Scale(1, 1, 1, 1.0/25.0)
screen.DrawImage(gophersImage, op)
}
}
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
// Decode an image from the image file's byte slice.
// Now the byte slice is generated with //go:generate for Go 1.15 or older.
// If you use Go 1.16 or newer, it is strongly recommended to use //go:embed to embed the image file.
// See https://pkg.go.dev/embed for more details.
img, _, err := image.Decode(bytes.NewReader(images.FiveYears_jpg))
if err != nil {
log.Fatal(err)
}
gophersImage = ebiten.NewImageFromImage(img)
ebiten.SetWindowSize(screenWidth, screenHeight)
ebiten.SetWindowTitle("Blur (Ebiten Demo)")
if err := ebiten.RunGame(&Game{}); err != nil {
log.Fatal(err)
}
}