add gophermark example

community/gophermark/README.md

@@ -0,0 +1,10 @@
+# Gophermark
+
+Simple Bunnymark for Pixel featuring the Gopher. For improvements just make your own pull request or write me a message.
+
+Made by [David Linus Briemann](https://github.com/dbriemann/).
+
+## Controls
+
+ESC - Quit
+Press left mouse button - add many gophers.

community/gophermark/gophermark.go

@@ -0,0 +1,131 @@
+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"
+)
+
+type gopher struct {
+	pos pixel.Vec
+	vel pixel.Vec
+	// angle float32
+}
+
+// newGopher creates a gopher with given position and random velocity.
+func newGopher(p pixel.Vec) gopher {
+	g := gopher{
+		pos: p,
+	}
+	v := pixel.V(1, 0)
+	v = v.Rotated(rand.Float64() * 2 * math.Pi)
+	g.vel = v.Scaled(rand.Float64()*100 + 50)
+	return g
+}
+
+// update updates the gophers position and ensures he stays on screen.
+func (g *gopher) update(dt float64) {
+	g.pos = g.pos.Add(g.vel.Scaled(dt))
+	if g.pos.X <= pic.Bounds().W()/2 {
+		g.vel.X *= -1
+	} else if g.pos.X > win.Bounds().Max.X-pic.Bounds().W()/2 {
+		g.vel.X *= -1
+	}
+	if g.pos.Y <= pic.Bounds().H()/2 {
+		g.vel.Y *= -1
+	} else if g.pos.Y > win.Bounds().Max.Y-pic.Bounds().H()/2 {
+		g.vel.Y *= -1
+	}
+}
+
+var (
+	win     *pixelgl.Window
+	pic     pixel.Picture
+	sprite  *pixel.Sprite
+	gophers []gopher
+	frames  = 0
+	second  = time.Tick(time.Second)
+)
+
+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() {
+	rand.Seed(time.Now().UnixNano())
+	cfg := pixelgl.WindowConfig{
+		Title:  "Gophermark",
+		Bounds: pixel.R(0, 0, 1000, 800),
+	}
+	w, err := pixelgl.NewWindow(cfg)
+	if err != nil {
+		panic(err)
+	}
+	win = w
+
+	p, err := loadPicture("gopher.png")
+	if err != nil {
+		panic(err)
+	}
+	pic = p
+
+	batch := pixel.NewBatch(&pixel.TrianglesData{}, pic)
+	sprite = pixel.NewSprite(pic, pic.Bounds())
+
+	for i := 0; i < 1000; i++ {
+		gophers = append(gophers, newGopher(pixel.V(win.Bounds().W()/2, win.Bounds().H()/2)))
+	}
+
+	last := time.Now()
+	for !win.Closed() && !win.JustPressed(pixelgl.KeyEscape) {
+		dt := time.Since(last).Seconds()
+		last = time.Now()
+
+		if win.Pressed(pixelgl.MouseButtonLeft) {
+			mouse := win.MousePosition()
+			for i := 0; i < 10; i++ {
+				gophers = append(gophers, newGopher(mouse))
+			}
+		}
+
+		batch.Clear()
+		for i := 0; i < len(gophers); i++ {
+			gophers[i].update(dt)
+			sprite.Draw(batch, pixel.IM.Moved(gophers[i].pos))
+		}
+
+		win.Clear(colornames.Black)
+		batch.Draw(win)
+		win.Update()
+
+		frames++
+		select {
+		case <-second:
+			win.SetTitle(fmt.Sprintf("%s | Gophers: %d | FPS: %d", cfg.Title, len(gophers), frames))
+			frames = 0
+		default:
+		}
+	}
+}
+
+func main() {
+	pixelgl.Run(run)
+}