algebra.go

package main

type vector struct {
	x, y, z float64
}

camera.go

package main

import "github.com/banthar/gl"
import "github.com/banthar/glu"

type camera struct {
	position vector
	target vector
	up vector
}

func (self *camera) use() {
	gl.MatrixMode(gl.MODELVIEW)
	gl.LoadIdentity()
	glu.LookAt(
		self.position.x, self.position.y, self.position.z,
		self.target.x, self.target.y, self.target.z,
		self.up.x, self.up.y, self.up.z)
}

main.go

package main

import "github.com/banthar/Go-SDL/sdl"
import "github.com/banthar/gl"
import "github.com/banthar/glu"

import "runtime"
import "time"

const screenWidth = 500
const screenHeight = 500

func setupVideo() {
	sdl.GL_SetAttribute(sdl.GL_DOUBLEBUFFER, 1)

	flags := uint32(sdl.OPENGL | sdl.GL_DOUBLEBUFFER)
	screen := sdl.SetVideoMode(screenWidth, screenHeight, 24, flags)
	if screen == nil {
		panic(sdl.GetError())
	}

	if gl.Init() != 0 {
		panic("Could not initialize OpenGL")
	}
}

func setupViewport() {
	gl.Viewport(0, 0, screenWidth, screenHeight)
	gl.MatrixMode(gl.PROJECTION)
	gl.LoadIdentity()

	glu.Perspective(45, screenWidth/screenHeight, 0.1, 100)
//	gl.Ortho(0, screenWidth, screenHeight, 0, 1, -1)
}

func mainLoop(drawFunc func(), eventFunc func(sdl.Event)) {
	drawTicker := time.NewTicker(time.Second / 60)
	eventTicker := time.NewTicker(time.Second / 100)

loop:
	for {
		select {
		case <-drawTicker.C:
			drawFunc()

		case <-eventTicker.C:
			for {
				if event := sdl.PollEvent(); event != nil {
					eventFunc(event)

					switch event.(type) {
					case *sdl.QuitEvent:
						break loop
					}
				}
			}
		}
	}
}

// this is a comment
func main() {
	// needed for proper working with C-bindings.
	// probably this line could be removed,
	// when bindings package updates.
	runtime.LockOSThread()

	if sdl.Init(sdl.INIT_VIDEO) != 0 {
		panic(sdl.GetError())
	}
	defer sdl.Quit()

	setupVideo()
	setupViewport()

	sdl.WM_SetCaption("Test", "Moped")

	cam := camera{}
	cam.position = vector{x:10, y: 10, z: 5}
	cam.target = vector{x:0, y: 0, z: 0}
	cam.up = vector{x: -1, y: -1, z: 1}

	cam.use()

	gl.ClearColor(0, 0, 0, 0)
	
	drawFunc := func() {
		gl.Clear(gl.COLOR_BUFFER_BIT|gl.DEPTH_BUFFER_BIT)

		gl.Color4f(1, 1, 1, 1)
		gl.Begin(gl.QUADS)

		gl.Vertex3d(-20, 20, 0)
		gl.Vertex3d(20, 20, 0)
		gl.Vertex3d(20, -20, 0)
		gl.Vertex3d(-20, -20, 0)
		
		gl.End()

		drawAxis()

		sdl.GL_SwapBuffers()
	}

	eventFunc := func(event sdl.Event) {
	}
	mainLoop(drawFunc, eventFunc)
}