Sync

Task/OpenGL/Go/opengl.go

@@ -0,0 +1,87 @@
+// triangle displays a smooth shaded triangle with OpenGL.
+package main
+
+import (
+	"log"
+	"runtime"
+	"time"
+
+	gl "github.com/chsc/gogl/gl21"
+	"github.com/mewmew/win"
+)
+
+// Window dimensions.
+const (
+	Width  = 640
+	Height = 480
+)
+
+func main() {
+	// OpenGL requires a dedicated OS thread.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	// Open window with the specified dimensions.
+	err := win.Open(Width, Height)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	defer win.Close()
+
+	// Initiate viewport.
+	resize(Width, Height)
+
+	// Register that we are interested in receiving close and resize events.
+	win.EnableCloseChan()
+	win.EnableResizeChan()
+
+	// 60 frames per second.
+	c := time.Tick(time.Second / 60)
+
+	// Event loop.
+	for {
+		select {
+		case <-win.CloseChan:
+			return
+		case e := <-win.ResizeChan:
+			resize(e.Width, e.Height)
+		case <-c:
+			draw()
+		}
+	}
+}
+
+// resize resizes the window to the specified dimensions.
+func resize(width, height int) {
+	gl.Viewport(0, 0, gl.Sizei(width), gl.Sizei(height))
+	gl.MatrixMode(gl.PROJECTION)
+	gl.LoadIdentity()
+	gl.Ortho(-30.0, 30.0, -30.0, 30.0, -30.0, 30.0)
+	gl.MatrixMode(gl.MODELVIEW)
+}
+
+// draw draws the triangle.
+func draw() {
+	gl.ClearColor(0.3, 0.3, 0.3, 0.0)
+	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
+
+	gl.ShadeModel(gl.SMOOTH)
+
+	gl.LoadIdentity()
+	gl.Translatef(-15.0, -15.0, 0.0)
+
+	gl.Begin(gl.TRIANGLES)
+
+	gl.Color3f(1.0, 0.0, 0.0)
+	gl.Vertex2f(0.0, 0.0)
+
+	gl.Color3f(0.0, 1.0, 0.0)
+	gl.Vertex2f(30.0, 0.0)
+
+	gl.Color3f(0.0, 0.0, 1.0)
+	gl.Vertex2f(0.0, 30.0)
+
+	gl.End()
+
+	win.SwapBuffers()
+}