pixel-examples/guide/04_pressing_keys_and_clicki.../main.go

102 lines
2.1 KiB
Go

package main
import (
"image"
"math"
"math/rand"
"os"
"time"
_ "image/png"
"github.com/faiface/pixel"
"github.com/faiface/pixel/pixelgl"
"golang.org/x/image/colornames"
)
func loadPicture(path string) (pixel.Picture, error) {
file, err := os.Open(path)
if err != nil {
return nil, err
}
defer file.Close()
img, _, err := image.Decode(file)
if err != nil {
return nil, err
}
return pixel.PictureDataFromImage(img), nil
}
func run() {
cfg := pixelgl.WindowConfig{
Title: "Pixel Rocks!",
Bounds: pixel.R(0, 0, 1024, 768),
VSync: true,
}
win, err := pixelgl.NewWindow(cfg)
if err != nil {
panic(err)
}
spritesheet, err := loadPicture("trees.png")
if err != nil {
panic(err)
}
var treesFrames []pixel.Rect
for x := spritesheet.Bounds().Min.X(); x < spritesheet.Bounds().Max.X(); x += 32 {
for y := spritesheet.Bounds().Min.Y(); y < spritesheet.Bounds().Max.Y(); y += 32 {
treesFrames = append(treesFrames, pixel.R(x, y, x+32, y+32))
}
}
var (
camPos = pixel.V(0, 0)
camSpeed = 500.0
camZoom = 1.0
camZoomSpeed = 1.2
trees []*pixel.Sprite
)
last := time.Now()
for !win.Closed() {
dt := time.Since(last).Seconds()
last = time.Now()
cam := pixel.IM.Scaled(camPos, camZoom).Moved(win.Bounds().Center() - camPos)
win.SetMatrix(cam)
if win.JustPressed(pixelgl.MouseButtonLeft) {
tree := pixel.NewSprite(spritesheet, treesFrames[rand.Intn(len(treesFrames))])
mouse := cam.Unproject(win.MousePosition())
tree.SetMatrix(pixel.IM.Scaled(0, 4).Moved(mouse))
trees = append(trees, tree)
}
if win.Pressed(pixelgl.KeyLeft) {
camPos -= pixel.X(camSpeed * dt)
}
if win.Pressed(pixelgl.KeyRight) {
camPos += pixel.X(camSpeed * dt)
}
if win.Pressed(pixelgl.KeyDown) {
camPos -= pixel.Y(camSpeed * dt)
}
if win.Pressed(pixelgl.KeyUp) {
camPos += pixel.Y(camSpeed * dt)
}
camZoom *= math.Pow(camZoomSpeed, win.MouseScroll().Y())
win.Clear(colornames.Forestgreen)
for _, tree := range trees {
tree.Draw(win)
}
win.Update()
}
}
func main() {
pixelgl.Run(run)
}