draw2d/samples/postscriptgl/postscriptgl.go

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2015-07-10 00:15:23 +00:00
// Open a OpenGL window and display a tiger interpreting a postscript file
package main
import (
"io/ioutil"
"log"
"math"
"os"
"runtime"
"strings"
"time"
"github.com/go-gl/gl/v2.1/gl"
"github.com/go-gl/glfw/v3.1/glfw"
"github.com/llgcode/draw2d/draw2dgl"
"github.com/llgcode/ps"
)
var postscriptContent string
var (
width, height int
rotate int
window *glfw.Window
)
func reshape(window *glfw.Window, w, h int) {
gl.ClearColor(1, 1, 1, 1)
//fmt.Println(gl.GetString(gl.EXTENSIONS))
gl.Viewport(0, 0, int32(w), int32(h)) /* Establish viewing area to cover entire window. */
gl.MatrixMode(gl.PROJECTION) /* Start modifying the projection matrix. */
gl.LoadIdentity() /* Reset project matrix. */
gl.Ortho(0, float64(w), 0, float64(h), -1, 1) /* Map abstract coords directly to window coords. */
gl.Scalef(1, -1, 1) /* Invert Y axis so increasing Y goes down. */
gl.Translatef(0, float32(-h), 0) /* Shift origin up to upper-left corner. */
gl.Enable(gl.BLEND)
gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
gl.Disable(gl.DEPTH_TEST)
width, height = w, h
}
func display() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
lastTime := time.Now()
gl.LineWidth(1)
gc := draw2dgl.NewGraphicContext(width, height)
gc.Translate(380, 400)
gc.Scale(1, -1)
rotate = (rotate + 1) % 360
gc.Rotate(float64(rotate) * math.Pi / 180)
gc.Translate(-380, -400)
interpreter := ps.NewInterpreter(gc)
reader := strings.NewReader(postscriptContent)
interpreter.Execute(reader)
dt := time.Now().Sub(lastTime)
log.Printf("Redraw in : %f ms\n", float64(dt)*1e-6)
gl.Flush() /* Single buffered, so needs a flush. */
}
func main() {
src, err := os.OpenFile("tiger.ps", 0, 0)
if err != nil {
log.Println("can't find postscript file.")
return
}
defer src.Close()
bytes, err := ioutil.ReadAll(src)
postscriptContent = string(bytes)
err = glfw.Init()
if err != nil {
panic(err)
}
defer glfw.Terminate()
window, err = glfw.CreateWindow(800, 800, "Show Tiger in OpenGL", nil, nil)
if err != nil {
panic(err)
}
window.MakeContextCurrent()
window.SetSizeCallback(reshape)
window.SetKeyCallback(onKey)
glfw.SwapInterval(1)
err = gl.Init()
if err != nil {
panic(err)
}
reshape(window, 800, 800)
for !window.ShouldClose() {
display()
window.SwapBuffers()
glfw.PollEvents()
// time.Sleep(2 * time.Second)
}
}
func onKey(w *glfw.Window, key glfw.Key, scancode int, action glfw.Action, mods glfw.ModifierKey) {
switch {
case key == glfw.KeyEscape && action == glfw.Press,
key == glfw.KeyQ && action == glfw.Press:
w.SetShouldClose(true)
}
}
func init() {
runtime.LockOSThread()
}