124 lines
3.6 KiB
Go
124 lines
3.6 KiB
Go
// Ported from GLUT's samples. Original copyright below applies.
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/* Copyright (c) Mark J. Kilgard, 1996. */
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/* This program is freely distributable without licensing fees
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and is provided without guarantee or warrantee expressed or
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implied. This program is -not- in the public domain. */
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/* This program is a response to a question posed by Gil Colgate
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<gcolgate@sirius.com> about how lengthy a program is required using
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OpenGL compared to using Direct3D immediate mode to "draw a
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triangle at screen coordinates 0,0, to 200,200 to 20,200, and I
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want it to be blue at the top vertex, red at the left vertex, and
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green at the right vertex". I'm not sure how long the Direct3D
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program is; Gil has used Direct3D and his guess is "about 3000
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lines of code". */
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package main
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import (
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"os"
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"math"
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"io/ioutil"
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"strings"
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"gl"
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"glut"
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"image"
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"draw2d.googlecode.com/hg/draw2d"
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"draw2d.googlecode.com/hg/draw2dgl"
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"draw2d.googlecode.com/hg/postscript"
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"log"
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"time"
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)
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var postscriptContent string
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func TestDrawCubicCurve(gc draw2d.GraphicContext) {
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// draw a cubic curve
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x, y := 25.6, 128.0
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x1, y1 := 102.4, 230.4
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x2, y2 := 153.6, 25.6
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x3, y3 := 230.4, 128.0
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gc.SetStrokeColor(image.NRGBAColor{0, 0, 0, 0xff})
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gc.SetLineWidth(10)
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gc.MoveTo(x, y)
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gc.CubicCurveTo(x1, y1, x2, y2, x3, y3)
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gc.Stroke()
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gc.SetStrokeColor(image.NRGBAColor{0xFF, 0x33, 0x33, 0x99})
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gc.SetLineWidth(6)
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// draw segment of curve
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gc.MoveTo(x, y)
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gc.LineTo(x1, y1)
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gc.MoveTo(x2, y2)
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gc.LineTo(x3, y3)
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gc.Stroke()
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}
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var (
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width, height int
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rotate int
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)
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func reshape(w, h int) {
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/* Because Gil specified "screen coordinates" (presumably with an
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upper-left origin), this short bit of code sets up the coordinate
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system to correspond to actual window coodrinates. This code
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wouldn't be required if you chose a (more typical in 3D) abstract
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coordinate system. */
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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, w, 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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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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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 := postscript.NewInterpreter(gc)
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reader := strings.NewReader(postscriptContent)
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lastTime := time.Nanoseconds()
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interpreter.Execute(reader)
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dt := time.Nanoseconds() - 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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glut.PostRedisplay()
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}
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func main() {
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src, err := os.OpenFile("../resource/postscript/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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glut.Init()
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glut.InitWindowSize(800, 800)
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glut.CreateWindow("single triangle")
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glut.DisplayFunc(display)
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glut.ReshapeFunc(reshape)
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glut.MainLoop()
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}
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