ebiten/examples/additive/main.go

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// Copyright 2016 Hajime Hoshi
//
// 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 jsgo
package main
import (
"bytes"
"image"
"image/color"
_ "image/png"
"log"
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"github.com/hajimehoshi/ebiten/v2"
"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
)
const (
screenWidth = 320
screenHeight = 240
)
var (
ebitenImage *ebiten.Image
)
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type Game struct{}
func (g *Game) Update(screen *ebiten.Image) error {
return nil
}
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func (g *Game) Draw(screen *ebiten.Image) {
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const (
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// The offset point to render the image.
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ox = 10
oy = 10
)
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screen.Fill(color.NRGBA{0x00, 0x40, 0x80, 0xff})
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// Draw the image with 'Source Alpha' composite mode (default).
op := &ebiten.DrawImageOptions{}
op.GeoM.Translate(ox, oy)
screen.DrawImage(ebitenImage, op)
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// Draw the image with 'Lighter (a.k.a Additive)' composite mode.
op = &ebiten.DrawImageOptions{}
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w, _ := ebitenImage.Size()
op.GeoM.Translate(ox+float64(w), oy)
op.CompositeMode = ebiten.CompositeModeLighter
screen.DrawImage(ebitenImage, op)
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}
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func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
// Decode image from a byte slice instead of a file so that
// this example works in any working directory.
// If you want to use a file, there are some options:
// 1) Use os.Open and pass the file to the image decoder.
// This is a very regular way, but doesn't work on browsers.
// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
// This works even on browsers.
// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
// This also works on browsers.
img, _, err := image.Decode(bytes.NewReader(images.Ebiten_png))
if err != nil {
log.Fatal(err)
}
ebitenImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
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ebiten.SetWindowSize(screenWidth*2, screenHeight*2)
ebiten.SetWindowTitle("Additive Blending (Ebiten Demo)")
if err := ebiten.RunGame(&Game{}); err != nil {
log.Fatal(err)
}
}