go-opengl-pixel/examples/guide/05_drawing_efficiently_with.../main.go

112 lines
2.2 KiB
Go

package main
import (
"fmt"
"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),
}
win, err := pixelgl.NewWindow(cfg)
if err != nil {
panic(err)
}
spritesheet, err := loadPicture("trees.png")
if err != nil {
panic(err)
}
batch := pixel.NewBatch(&pixel.TrianglesData{}, spritesheet)
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.ZV
camSpeed = 500.0
camZoom = 1.0
camZoomSpeed = 1.2
)
var (
frames = 0
second = time.Tick(time.Second)
)
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.Pressed(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))
tree.Draw(batch)
}
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)
batch.Draw(win)
win.Update()
frames++
select {
case <-second:
win.SetTitle(fmt.Sprintf("%s | FPS: %d", cfg.Title, frames))
frames = 0
default:
}
}
}
func main() {
pixelgl.Run(run)
}