g3nd

README

G3ND - G3N Game Engine Demo Program

G3ND is a demo/test program for the G3N Go 3D Game Engine. It contains demos of the main features of the engine and also some basic tests. It can also be used to learn how to use the game engine by examining the source code of the demo programs. It is very easy to create a new demo as the main program takes care of a lot of necessary initializations and housekeeping.

Dependencies for installation

G3ND imports the G3N game engine and so has the same dependencies as the engine itself. It needs an OpenGL driver installed in your system and on Unix like systems depends on some C libraries that can be installed using the platform package manager. In all cases it is necessary to have a gcc compatible 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.
• For Windows we tested the build using the mingw-w64 toolchain.

G3ND checks if audio libraries are installed in the system at runtime and if found enables the execution of audio demos. The following libraries are necessary for the audio demos:

• 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.
• For Windows its is necessary to install the following dlls: OpenAL32.dll, libogg.dll, libvorbis.dll and libvorbisfile.dll. See windows_audio_dlls for how to get them.

G3ND was only tested with Go1.7.4+.

Installation

The following command will download G3ND, the engine and all its dependencies, compile and install the packages and the g3nd binary. Make sure your GOPATH is set correctly.

go get -u github.com/g3n/g3nd

Note: G3ND comes with a data directory with media files: images, textures, models and audio files. Currently this directory has aproximately 50MB. The download and compilation may take some time. To see what is going on you can alternatively supply the verbose flag:

go get -u -v github.com/g3n/g3nd

Running

When G3ND is run without any command line parameters it shows the tree of categorized available demos at the left of its window and an empty center area to show the demo scene. Click on a category in the tree to expand it and then select a demo to show.

At the upper right corner is located the Control folder, which when clicked shows some controls which can change the parameters of the current demo.

To exit the program press ESC or close the window.

You can start G3ND to show a specific demo specifying the demo name (category plus "." plus name) in the command line such as:

>g3nd geometry.box

To check the maximum FPS rate (frames per second) of your system for any demo, run G3ND with the option -interval 0. Note that at least one core of your system CPU will run at 100% utilization. The FPS will be lower when the screen is maximized or full.

Creating a new demo/test

You can use the tests_model.go file as a template for your tests. You can can change it directly or copy it to a new file such as tests_mytest.go and experiment with the engine. Your new test will appear under the |tests| category with mytest name. The contents of the tests_model.go file are shown below, documenting the common structure of all demo/tests programs:

// This is a simple model for your tests
package main

import (
	"github.com/g3n/engine/graphic"
	"github.com/g3n/engine/math32"
)

// Sets the category and name of your test in the global map "TestMap"
// The category name choosen here starts with a "|" so it shows as the
// last category in list. Change "model" to the name of your test.
func init() {
	TestMap["|tests|.model"] = &testsModel{}
}

// This is your test object. You can store state here.
// By convention and to avoid conflict with other demo/tests name it
// using your test category and name.
type testsModel struct {
	grid *graphic.GridHelper    // Pointer to a GridHelper created in 'Initialize'
}

// This method will be called once when the test is selected from the list.
// ctx is a pointer to a Context structure built by the main program.
// It allows access to several important object such as the scene (ctx.Scene),
// camera (ctx.Camera) and the window (ctx.Win) among others.
// You can build your scene adding your objects to the ctx.Scene.
func (t *testsModel) Initialize(ctx *Context) {

	// Show axis helper
	ah := graphic.NewAxisHelper(1.0)
	ctx.Scene.Add(ah)

	// Creates a grid helper and saves its pointer in the test state
	t.grid = graphic.NewGridHelper(50, 1, &math32.Color{0.4, 0.4, 0.4})
	ctx.Scene.Add(t.grid)

	// Changes the camera position
	ctx.Camera.GetCamera().SetPosition(0, 4, 10)
}

// This method will be called at every frame
// You can animate your objects here.
func (t *testsModel) Render(ctx *Context) {

	// Rotate the grid, just for show.
	t.grid.AddRotationY(0.005)
}

Contributing

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

Documentation

Overview

This is a simple model for your tests