# G3N Go 3D Game Engine

G3N is a basic (for now!) OpenGL 3D Game Engine written in Go.
G3N was heavily inspired and based on the [three.js](https://threejs.org/) Javascript 3D library.
If you are curious about G3N and would like to see it in action
we recommend that you install the [G3N demo program](https://github.com/g3n/g3nd).

# Dependencies

The engine needs an OpenGL driver installed in the system and
on Unix like systems depends on some C libraries that must be installed.
In all cases it is necessary to have a C compiler installed.

* For Ubuntu/Debian-like Linux distributions, install `libgl1-mesa-dev` and `xorg-dev` packages.
* For CentOS/Fedora-like Linux distributions, install `libX11-devel libXcursor-devel libXrandr-devel libXinerama-devel mesa-libGL-devel libXi-devel` packages.
* Currently it was not tested on OS X. We encourage some feedback.
* For Windows it is recommended to have MingGW vx.x.x installed.

G3N supports spatial audio using external libraries, but G3N loads these libraries
dinamically on demand, so you can install G3N and build a 3D application
(not using audio) without installing these libraries.

The following libraries are necessary for the optional audio support:

* For Ubuntu/Debian-like Linux distributions, install `libopenal1` and `libvorbisfile3`
* For CentOS/Fedora-like Linux distributions, install `libopenal1` and `libvorbisfile3`
* Currently it was not tested on OS X. We encourage some feedback.
* For Windows install `OpenAL32.dll` and ???

G3N was only tested with Go1.7.4+

# Installation

go get -u github.com/g3n/engine

# Features

* Scene graph based
* supports perspective and orthographic cameras.
  Orbit control to move (zoom, rotate and pan) camera using the mouse or keyboard
* supports perspective and orthographic cameras


# Basic application

The following code shows a minimum G3N application [hellog3n](https://github.com/g3n/engine/hellog3n)
which shows a wireframed sphere rotating.


```
package main

import (
	"github.com/g3n/engine/camera"
	"github.com/g3n/engine/core"
	"github.com/g3n/engine/geometry"
	"github.com/g3n/engine/gls"
	"github.com/g3n/engine/graphic"
	"github.com/g3n/engine/light"
	"github.com/g3n/engine/material"
	"github.com/g3n/engine/math32"
	"github.com/g3n/engine/renderer"
	"github.com/g3n/engine/window"
	"math"
	"runtime"
)

func main() {

	// Creates window and OpenGL context
	win, err := window.New("glfw", 800, 600, "Hello G3N", false)
	if err != nil {
		panic(err)
	}

	// OpenGL functions must be executed in the same thread where
	// the context was created (by window.New())
	runtime.LockOSThread()

	// Create OpenGL state
	gs, err := gls.New()
	if err != nil {
		panic(err)
	}

	// Creates scene for 3D objects
	scene := core.NewNode()

	// Adds white ambient light to the scene
	ambLight := light.NewAmbient(&math32.Color{1.0, 1.0, 1.0}, 0.5)
	scene.Add(ambLight)

	// Adds a perspective camera to the scene
	width, height := win.GetSize()
	aspect := float32(width) / float32(height)
	camera := camera.NewPerspective(65, aspect, 0.01, 1000)
	camera.SetPosition(0, 0, 5)

	// Add an axis helper
	axis := graphic.NewAxisHelper(2)
	scene.Add(axis)

	// Creates a wireframe sphere positioned at the center of the scene
	geom := geometry.NewSphere(2, 16, 16, 0, math.Pi*2, 0, math.Pi)
	mat := material.NewStandard(math32.NewColor(1, 1, 1))
	mat.SetSide(material.SideDouble)
	mat.SetWireframe(true)
	sphere := graphic.NewMesh(geom, mat)
	scene.Add(sphere)

	// Creates a renderer and adds default shaders
	rend := renderer.NewRenderer(gs)
	err = rend.AddDefaultShaders()
	if err != nil {
		panic(err)
	}

	// Sets window background color
	gs.ClearColor(0, 0, 0, 1.0)

	// Render loop
	for !win.ShouldClose() {

		// Clear buffers
		gs.Clear(gls.DEPTH_BUFFER_BIT | gls.STENCIL_BUFFER_BIT | gls.COLOR_BUFFER_BIT)

		// Rotates the sphere a bit around the Z axis (up)
		sphere.AddRotationY(0.005)

		// Render the scene using the specified camera
		rend.Render(scene, camera)

		// Update window and checks for I/O events
		win.SwapBuffers()
		win.PollEvents()
	}
}
```

# Documentation

* For the engine API reference, please see https://godoc.org/github.com/g3n/engine
* For

# Contributing

If you spot a bug or create a new feature you are encouraged to
send pull requests.