115 lines
2.7 KiB
Go
115 lines
2.7 KiB
Go
// Open a OpenGL window and display a tiger interpreting a postscript file
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package main
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import (
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"io/ioutil"
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"log"
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"math"
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"os"
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"runtime"
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"strings"
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"time"
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"github.com/go-gl/gl/v2.1/gl"
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"github.com/go-gl/glfw/v3.1/glfw"
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"github.com/llgcode/draw2d/draw2dgl"
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"github.com/llgcode/ps"
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)
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var postscriptContent string
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var (
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width, height int
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rotate int
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window *glfw.Window
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)
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func reshape(window *glfw.Window, w, h int) {
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gl.ClearColor(1, 1, 1, 1)
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//fmt.Println(gl.GetString(gl.EXTENSIONS))
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gl.Viewport(0, 0, int32(w), int32(h)) /* Establish viewing area to cover entire window. */
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gl.MatrixMode(gl.PROJECTION) /* Start modifying the projection matrix. */
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gl.LoadIdentity() /* Reset project matrix. */
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gl.Ortho(0, float64(w), 0, float64(h), -1, 1) /* Map abstract coords directly to window coords. */
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gl.Scalef(1, -1, 1) /* Invert Y axis so increasing Y goes down. */
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gl.Translatef(0, float32(-h), 0) /* Shift origin up to upper-left corner. */
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gl.Enable(gl.BLEND)
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gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
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gl.Disable(gl.DEPTH_TEST)
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width, height = w, h
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}
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func display() {
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gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
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lastTime := time.Now()
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gl.LineWidth(1)
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gc := draw2dgl.NewGraphicContext(width, height)
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gc.Translate(380, 400)
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gc.Scale(1, -1)
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rotate = (rotate + 1) % 360
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gc.Rotate(float64(rotate) * math.Pi / 180)
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gc.Translate(-380, -400)
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interpreter := ps.NewInterpreter(gc)
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reader := strings.NewReader(postscriptContent)
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interpreter.Execute(reader)
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dt := time.Now().Sub(lastTime)
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log.Printf("Redraw in : %f ms\n", float64(dt)*1e-6)
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gl.Flush() /* Single buffered, so needs a flush. */
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}
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func main() {
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src, err := os.OpenFile("tiger.ps", 0, 0)
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if err != nil {
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log.Println("can't find postscript file.")
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return
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}
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defer src.Close()
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bytes, err := ioutil.ReadAll(src)
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postscriptContent = string(bytes)
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err = glfw.Init()
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if err != nil {
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panic(err)
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}
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defer glfw.Terminate()
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window, err = glfw.CreateWindow(800, 800, "Show Tiger in OpenGL", nil, nil)
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if err != nil {
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panic(err)
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}
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window.MakeContextCurrent()
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window.SetSizeCallback(reshape)
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window.SetKeyCallback(onKey)
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glfw.SwapInterval(1)
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err = gl.Init()
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if err != nil {
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panic(err)
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}
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reshape(window, 800, 800)
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for !window.ShouldClose() {
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display()
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window.SwapBuffers()
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glfw.PollEvents()
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// time.Sleep(2 * time.Second)
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}
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}
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func onKey(w *glfw.Window, key glfw.Key, scancode int, action glfw.Action, mods glfw.ModifierKey) {
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switch {
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case key == glfw.KeyEscape && action == glfw.Press,
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key == glfw.KeyQ && action == glfw.Press:
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w.SetShouldClose(true)
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}
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}
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func init() {
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runtime.LockOSThread()
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}
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