ebiten/example/sprites/main.go

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// Copyright 2015 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.
package main
import (
"fmt"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
_ "image/png"
"log"
"math/rand"
)
const (
screenWidth = 320
screenHeight = 240
)
var (
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ebitenImage *ebiten.Image
ebitenImageWidth = 0
ebitenImageHeight = 0
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)
type Sprite struct {
image *ebiten.Image
x int
y int
vx int
vy int
}
func (s *Sprite) Update() {
s.x += s.vx
s.y += s.vy
if s.x < 0 {
s.x = -s.x
s.vx = -s.vx
}
if s.y < 0 {
s.y = -s.y
s.vy = -s.vy
}
w, h := s.image.Size()
if screenWidth <= s.x+w {
s.x = 2*(screenWidth-w) - s.x
s.vx = -s.vx
}
if screenHeight <= s.y+h {
s.y = 2*(screenHeight-h) - s.y
s.vy = -s.vy
}
}
type Sprites []*Sprite
func (s Sprites) Update() {
for _, sprite := range s {
sprite.Update()
}
}
func (s Sprites) Len() int {
return len(s)
}
func (s Sprites) Dst(i int) (x0, y0, x1, y1 int) {
ss := s[i]
return ss.x, ss.y, ss.x + ebitenImageWidth, ss.y + ebitenImageHeight
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}
func (s Sprites) Src(i int) (x0, y0, x1, y1 int) {
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return 0, 0, ebitenImageWidth, ebitenImageHeight
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}
var sprites = make(Sprites, 10000)
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func update(screen *ebiten.Image) error {
sprites.Update()
op := &ebiten.DrawImageOptions{
ImageParts: sprites,
}
op.ColorM.Scale(1.0, 1.0, 1.0, 0.5)
if err := screen.DrawImage(ebitenImage, op); err != nil {
return err
}
ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f\nNum of sprites: %d", ebiten.CurrentFPS(), sprites.Len()))
return nil
}
func main() {
var err error
ebitenImage, _, err = ebitenutil.NewImageFromFile("images/ebiten.png", ebiten.FilterNearest)
if err != nil {
log.Fatal(err)
}
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ebitenImageWidth, ebitenImageHeight = ebitenImage.Size()
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for i, _ := range sprites {
w, h := ebitenImage.Size()
x, y := rand.Intn(screenWidth-w), rand.Intn(screenHeight-h)
vx, vy := 2*rand.Intn(2)-1, 2*rand.Intn(2)-1
sprites[i] = &Sprite{
image: ebitenImage,
x: x,
y: y,
vx: vx,
vy: vy,
}
}
if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Sprites (Ebiten Demo)"); err != nil {
log.Fatal(err)
}
}