content: add bench render example

content/assets/bench-render/image/go.mod

@@ -0,0 +1,8 @@
+module x
+
+go 1.16
+
+require (
+	github.com/go-gl/gl v0.0.0-20190320180904-bf2b1f2f34d7
+	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20201108214237-06ea97f0c265
+)

content/assets/bench-render/image/go.sum

@@ -0,0 +1,4 @@
+github.com/go-gl/gl v0.0.0-20190320180904-bf2b1f2f34d7 h1:SCYMcCJ89LjRGwEa0tRluNRiMjZHalQZrVrvTbPh+qw=
+github.com/go-gl/gl v0.0.0-20190320180904-bf2b1f2f34d7/go.mod h1:482civXOzJJCPzJ4ZOX/pwvXBWSnzD4OKMdH4ClKGbk=
+github.com/go-gl/glfw/v3.3/glfw v0.0.0-20201108214237-06ea97f0c265 h1:BcbKYUZo/TKPsiSh7LymK3p+TNAJJW3OfGO/21sBbiA=
+github.com/go-gl/glfw/v3.3/glfw v0.0.0-20201108214237-06ea97f0c265/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=

content/assets/bench-render/image/main.go

@@ -0,0 +1,125 @@
+// Copyright (c) 2021 The golang.design Initiative Authors.
+// All rights reserved.
+//
+// The code below is produced by Changkun Ou <[email protected]>.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"image"
+	"image/draw"
+	_ "image/jpeg"
+	_ "image/png"
+	"os"
+	"runtime"
+	"runtime/trace"
+	"time"
+	"unsafe"
+
+	"github.com/go-gl/gl/v2.1/gl"
+	"github.com/go-gl/glfw/v3.3/glfw"
+)
+
+func init() {
+	runtime.LockOSThread()
+}
+
+func main() {
+	run := flag.Bool("run", false, "start test")
+	traceF := flag.String("trace", "trace.out", "trace file, default: trace.out")
+	traceT := flag.String("d", "10s", "trace duration, default: 10s")
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, `usage: go run main.go -run [-trace FILENAME -d DURATION]
+options:
+`)
+		flag.PrintDefaults()
+	}
+	flag.Parse()
+	if !*run {
+		flag.Usage()
+		os.Exit(2)
+	}
+
+	d, err := time.ParseDuration(*traceT)
+	if err != nil {
+		flag.Usage()
+		os.Exit(2)
+	}
+
+	err = glfw.Init()
+	if err != nil {
+		panic(err)
+	}
+
+	w, err := glfw.CreateWindow(800, 600, "image", nil, nil)
+	if err != nil {
+		panic(err)
+	}
+	glfw.WindowHint(glfw.DoubleBuffer, glfw.False)
+	w.MakeContextCurrent()
+
+	err = gl.Init()
+	if err != nil {
+		panic(err)
+	}
+
+	f, err := os.Open("../ou.png")
+	if err != nil {
+		panic(err)
+	}
+	img, _, err := image.Decode(f)
+	if err != nil {
+		panic(err)
+	}
+
+	go func() {
+		f, _ := os.Create(*traceF)
+		defer f.Close()
+		trace.Start(f)
+		defer trace.Stop()
+		time.Sleep(d)
+		w.SetShouldClose(true)
+	}()
+
+	total := time.Duration(0)
+	count := 0
+	for !w.ShouldClose() {
+		t := time.Now()
+		flush(w, img, img.Bounds())
+		total += time.Now().Sub(t)
+		count++
+
+		glfw.WaitEventsTimeout(1.0 / 30)
+	}
+	timePerFlush := total / time.Duration(count)
+	fmt.Printf("%v, fps: %v\n", timePerFlush, int(time.Second/timePerFlush))
+}
+
+func flush(w *glfw.Window, img image.Image, canvas image.Rectangle) {
+	bounds := img.Bounds()
+	canvas = canvas.Intersect(bounds)
+	if canvas.Empty() {
+		return
+	}
+
+	tmp := image.NewRGBA(canvas)
+	draw.Draw(tmp, canvas, img, canvas.Min, draw.Src)
+	gl.DrawBuffer(gl.FRONT)
+	gl.Viewport(
+		int32(bounds.Min.X), int32(bounds.Min.Y),
+		int32(bounds.Dx()), int32(bounds.Dy()),
+	)
+	gl.RasterPos2d(
+		-1+2*float64(canvas.Min.X)/float64(bounds.Dx()),
+		+1-2*float64(canvas.Min.Y)/float64(bounds.Dy()),
+	)
+	gl.PixelZoom(1, -1)
+	gl.DrawPixels(
+		int32(canvas.Dx()), int32(canvas.Dy()),
+		gl.RGBA, gl.UNSIGNED_BYTE,
+		unsafe.Pointer(&tmp.Pix[0]),
+	)
+	gl.Flush()
+}