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29. August 2018


Looking for a small but full featured open source (LGPL) C++ 14 game engine with a built in editor?  If so, the Limon Game Engine might be the perfect choice for you!  Primary features of the Limon game are:

  • Model loading using Assimp
  • Skeletal animations
  • Realtime shadows
  • Rigid body physics
  • 3D spatial sound
  • Preliminary AI
  • In game map editor
  • Trigger volumes
  • API for Custom Trigger code
  • Loading shared libraries that has Trigger code
  • Creating Animations in editor

Additionally the engine is documented, with the manual available here.  The source code is cleanly written C++ 14 code and is available on Github.  The engine works on Windows, Mac and Linux with binaries available for download here.  If you are interested in seeing the engine in action, be sure to check out our hands-on video, embedded below.  There are additional videos available on the Limon YouTube channel, available here.

EDIT – The author in response to the video has released an updated version, with the editor key changed in 0.5.2 to the much more sensible F2 key.

GameDev News


2. August 2018


The Toy Engine was just released yesterday.  The Toy Engine is a cross platform modular C++ open source game engine currently available under the GPL license.  The engine is quite young so you should expect some instability and missing features.  The developer @HugoAM has been very responsive to feedback and has announced that the license will be changed to something more permissive in time.  The source code is available now on GitHub.


The guiding design principals behind the Toy engine are:

  • simple and lightweight, simplicity is the core aim and philosophy behind toy. the codebase is about one-tenth the size of competing engines, and toy is so light, the whole editor runs in your browser !
  • modular, each functionality is enclosed in a small, simple, easy to understand code building block. most of these blocks lie in the underlying mud library.
  • extensible, as a collection of modules, toy is a perfect fit to build your own game technology, keeping full control over the components you use, the application design and the control flow.
  • game code first, toy is first and foremost meant to build games in native c++ code, in direct contact with the core systems. this allows for much greater control than typical scripting in-engine.
  • versatile, toy is designed from the start with complex games in mind, such as strategy or role playing games, by giving full control over its powerful user interface and rendering systems.
  • zero-cost tools, reflection automatically extends your game core code for seamless scripting, editing, inspection of your game objects, types and procedures in the built-in tools/editor.
  • educative, toy aims to provide simplest technical solutions to typical game programming problems, easily studied and understood, hoping to be a driver of education on game development topics.
  • fast iteration, coupling seamless bindings of both built-in systems and game code to various scripting languages, hot-reload of native code, and immediate UI and rendering, toy provides fast iteration speeds.

The Toy engine is built upon the underlying mud framework, which provides the low level cross platform functionality that toy is built on top of.  The mud framework is built on the much better ZLib open source license.  You can compile Toy on both Windows and Linux.  Toy games can be run on most modern platforms including mobile, desktops and even HTML via EMScripten.  The video embedded below demonstrates how to get started using Visual Studio 2017.

GameDev News


22. July 2018


Raylib is a cross platform open source C based game framework that is absolutely perfect for beginners that want to get started with game development using C or C++.  It provides a complete C/C++ turn key game development setup with tools, editor and framework all pre-configured, just download and start coding.  If you are interested in learning more about Raylib be sure to check out our earlier video available here.  Raylib just released version 2.0, which now has less external dependencies.  Perhaps the most exciting new feature of this release is support for various Linux and *nix based operating system, a long requested feature.

The highlights of this release from the Raylib forums:

  • Complete removal of external dependencies. Finally, raylib does not require external libraries to be installed and linked along with raylib, all required libraries are contained and compiled within raylib. Obviously some external libraries are required but only the strictly platform-dependant ones, that comes installed with the OS. So, raylib becomes a self-contained platform-independent games development library.
  • Full redesign of audio module to use the amazing mini_al audio library, along with external dependencies removal, OpenAL library has been replaced by mini_al, this brand new library offers automatic dynamic linking with default OS audio systems. Undoubtly, the perfect low-level companion for raylib audio module!
  • Support for continuous integration building through AppVeyor and Travis CI. As a consequence, raylib GitHub develop branch has been completely removed simplyfing the code-base to a single master branch, always stable. Every time a new commit is deployed, library is compiled for up-to 12 different configurations, including multiple platforms, 32bit/64bit and multiple compiler options! All those binaries are automatically attached to any new release!
  • More platforms supported and tested, including BSD family (FreeBSD, openBSD, NetBSD, DragonFly) and Linux-based family platforms (openSUSE, Debian, Ubuntu, Arch, NixOS...). raylib has already been added to some package managers! Oh, and last but not less important, Android 64bit is already supported by raylib!
  • Support for TCC compiler! Thanks to the lack of external dependencies, raylib can now be easily compiled with a minimal toolchain, like the one provide by Tiny C Compiler. It opens the door to an amazing future, allowing, for example, static linkage of libtcc for runtime compilation of raylib-based code... and the library itself if required! Moreover, TCC is blazing fast, it can compile all raylib in just a few seconds!
  • Refactored all raylib configuration #defines into a centralized config.h header, with more than 40 possible configuration options to compile a totally customizable raylib version including only desired options like supported file-formats or specific functionality support. It allows generating a trully ligth-weight version of the library if desired!
  • A part of that, lots of new features, like a brand new font rendering and packaging system for TTF fonts with SDF support (thanks to the amazing STB headers), new functions for CPU image data manipulation, new orthographic 3d camera mode, a complete review of raymath.h single-file header-only library for better consistency and performance, new examples and way, way more.
  • As always, examples and templates have been reviewed and improved to work with new features; some new examples have been added and templates have been prepared for real multiplatform support including Android and HTML5.

These are only the highlight features, for complete details of the 2.0 release are available in the changelog.  Raylib is available here, while the source code is available on Github.

GameDev News


18. May 2018


It’s not very often a game engine takes me completely by surprise.  Especially a full featured, open source, C++ based, cross platform, heavily documented, feature rich, high performance 3D game engine.  Well that’s exactly what happened with the G3D Innovation Engine.  The primary maintainers are Morgan McGuire (@CasualEffects) who is currently an educator as well as a VR scientist at NVIDIA and previously worked on games such as Skylanders, Titan Quest and the Unity game engine, as well as Michael Mara at Standard University and Oculus Research.

The G3D Engine is self described as:

The G3D Innovation Engine is a commercial-grade C++ 3D engine available as Open Source. ss

G3D supports hardware accelerated real-time rendering, off-line rendering like ray tracing, and general purpose computation on GPUs. Its design emphasizes rapid prototyping and innovation, particularly of rendering and game algorithms.

G3D provides a set of routines and structures so common that they are needed in almost every graphics program. It makes low-level libraries like OpenGL, network sockets, and audio channels easier to use without limiting functionality or performance. G3D is a carefully designed, feature-rich base on which to prototype your 3D application.


Beyond being a capable engine it is also an incredible learning resource.  The engine is bundled with over 6GB of assets to experiment with, as well as over a dozen robust ss2samples with thoroughly documented source code.  One of the samples is even a full blown first person shooter, while another demonstrates a Minecraft-esque voxel based level.  There are also examples that show you how to work at the lowest level directly with OpenGL as well as advanced examples showcasing functionality such as real-time raytracing, lighting effects, procedural geometry and even VR.

Additionally each example can easily embed a suite of tools directly, enabling you to screen shot or video capture, change camera settings on the fly or launch the built in profiler.  There is even a complete scene editor built in, allowing you to place entities directly in your scene via simple drag and drop, turning your application into a minimalistic level editor.


Remember back at the beginning I mentioned that the maintainer was also an educator?  He has also authored a companion called the Graphics Codex which goes hand in hand with the G3D game engine.  For a mere $10 you gain access to an advanced reference that may just be one of the single best ways of learning computer graphics GIF2topics such as ray casting, BSDF, rendering and more.  You can see a full chapter list here.  So if you are trying to learn more advanced graphics programming, G3D is certainly a great resource.  Keep in mind however, this material was used with a 300s level graphics course, so you are going to need a solid foundation in math to follow along.

Purchasing the Graphics Codex is by no means a requirement however.  One thing open source projects often suffer from is poor documentation.  Thankfully this certainly isn’t the case with the G3D engine.   There is an extensive manual available here, as well as a comprehensive set of API references.  As mentioned earlier, the engine is also loaded with well documented samples.

If you are looking for a low level foundation to build your game on, a framework to do some graphical experiments or simply are looking for a way to learn more about modern graphics programming, I can think of little reason not to suggest checking out the G3D Innovation Engine. 


If you are interested in learning more about the G3D Innovation Engine, be sure to check out our hands-on video available here and embedded below.  I am almost certain you will be amazed.

GameDev News Programming


14. May 2018

Details


orx-project.org

ZLib License

View On YouTube

  

Orx is a cross platform open sourced 2D game framework written in C and available on Github under the permissive ZLib source license.  What makes Orx somewhat unique among it’s peers is the data driven approach that Orx takes.  Instead of storing game data using a collection of objects in code, it is instead split out into data files.  This enables you to quickly change the content of your game without having to do a recompilation.   So for example you make have an entry like the following for defining the camera in your scene:


[Viewport]
Camera            = Camera
BackgroundColor   = (255, 180, 0)

[Camera]
FrustumWidth  = 1024
FrustumHeight = 768
FrustumFar    = 1.0
FrustumNear   = 0.0
Position      = (0.0, 0.0, -1.0)
;Zoom          = 3.0

By editing this config file you can make major alterations to the camera without having to recompile your code.  Chance the FrustrumWidth in the ini file, and the next time you run your game’s window will be smaller.  Now let’s look at the code required to consume the Viewport/Camera data in your C/C++ application:

orxViewport_CreateFromConfig("Viewport");

Yep, that’s it.  This will create the viewport, notice the camera property and create one of them as well, entirely driven by data. 


This approach has a couple of advantages.  First it creates a clean separation of code and data which should in theory make for easier to maintain code.  It also takes these values out of the compilation process, meaning changes do not require you to recompile your code.  Additionally, this data driven approach makes creating tools for you game a cinch, as you are simply writing out simple easily understood text files. 


There are of course disadvantages too.  Since you moved the code out from the compiler, you lose features such as intellisense as well as compile time error checking.  Moving more details off into data files can make hunting down bugs even more difficult.


Let’s take a quick look at one of the samples from the Orx tutorials, with the comments stripped down for brevity.

#include "orx.h"
orxOBJECT *pstSoldier;

orxSTATUS orxFASTCALL EventHandler(const orxEVENT *_pstEvent)
{
  orxANIM_EVENT_PAYLOAD *pstPayload;

  /* Gets event payload */
  pstPayload = (orxANIM_EVENT_PAYLOAD *)_pstEvent->pstPayload;

  /* Depending on event type */
  switch(_pstEvent->eID)
  {
    case orxANIM_EVENT_START:
    {
      /* Logs info */
      orxLOG("Animation <%s>@<%s> has started!", pstPayload->zAnimName, orxObject_GetName(orxOBJECT(_pstEvent->hRecipient)));

      break;
    }

    case orxANIM_EVENT_STOP:
    {
      /* Logs info */
      orxLOG("Animation <%s>@<%s> has stopped!", pstPayload->zAnimName, orxObject_GetName(orxOBJECT(_pstEvent->hRecipient)));

      break;
    }

    case orxANIM_EVENT_CUT:
    {
      /* Logs info */
      orxLOG("Animation <%s>@<%s> has been cut!", pstPayload->zAnimName, orxObject_GetName(orxOBJECT(_pstEvent->hRecipient)));

      break;
    }

    case orxANIM_EVENT_LOOP:
    {
      /* Logs info */
      orxLOG("Animation <%s>@<%s> has looped!", pstPayload->zAnimName, orxObject_GetName(orxOBJECT(_pstEvent->hRecipient)));

      break;
    }

    case orxANIM_EVENT_CUSTOM_EVENT:
    {
       /* Logs info */
       orxLOG("Animation <%s>@<%s> has sent the event [%s]!", pstPayload->zAnimName, orxObject_GetName(orxOBJECT(_pstEvent->hRecipient)), pstPayload->stCustom.zName);

      break;
    }
  }

  /* Done! */
  return orxSTATUS_SUCCESS;
}

/** Update callback
 */
void orxFASTCALL Update(const orxCLOCK_INFO *_pstClockInfo, void *_pstContext)
{
  orxVECTOR vScale;

  /* Is walk right active? */
  if(orxInput_IsActive("GoRight"))
  {
    /* Sets walk right as target anim */
    orxObject_SetTargetAnim(pstSoldier, "WalkRight");
  }
  /* Is walk left active? */
  else if(orxInput_IsActive("GoLeft"))
  {
    /* Sets walk left as target anim */
    orxObject_SetTargetAnim(pstSoldier, "WalkLeft");
  }
  /* No walk active */
  else
  {
    /* Removes target anim */
    orxObject_SetTargetAnim(pstSoldier, orxNULL);
  }

  /* Is scale up active ? */
  if(orxInput_IsActive("ScaleUp"))
  {
    /* Scales up the soldier */
    orxObject_SetScale(pstSoldier, orxVector_Mulf(&vScale, orxObject_GetScale(pstSoldier, &vScale), orx2F(1.02f)));
  }
  /* Is scale down active? */
  if(orxInput_IsActive("ScaleDown"))
  {
    /* Scales down the soldier */
    orxObject_SetScale(pstSoldier, orxVector_Mulf(&vScale, orxObject_GetScale(pstSoldier, &vScale), orx2F(0.98f)));
  }
}


/** Inits the tutorial
 */
orxSTATUS orxFASTCALL Init()
{
  orxCLOCK       *pstClock;
  orxINPUT_TYPE   eType;
  orxENUM         eID;
  orxINPUT_MODE   eMode;
  const orxSTRING zInputWalkLeft;
  const orxSTRING zInputWalkRight;
  const orxSTRING zInputScaleUp;
  const orxSTRING zInputScaleDown;

  /* Gets input binding names */
  orxInput_GetBinding("GoLeft", 0, &eType, &eID, &eMode);
  zInputWalkLeft  = orxInput_GetBindingName(eType, eID, eMode);

  orxInput_GetBinding("GoRight", 0, &eType, &eID, &eMode);
  zInputWalkRight = orxInput_GetBindingName(eType, eID, eMode);

  orxInput_GetBinding("ScaleUp", 0, &eType, &eID, &eMode);
  zInputScaleUp   = orxInput_GetBindingName(eType, eID, eMode);

  orxInput_GetBinding("ScaleDown", 0, &eType, &eID, &eMode);
  zInputScaleDown = orxInput_GetBindingName(eType, eID, eMode);

  /* Displays a small hint in console */
  orxLOG("\n- '%s' & '%s' will change the soldier's animations\n- '%s' & '%s' will scale the soldier", zInputWalkLeft, zInputWalkRight, zInputScaleUp, zInputScaleDown);

  /* Registers event handler */
  orxEvent_AddHandler(orxEVENT_TYPE_ANIM, EventHandler);

  /* Creates viewport */
  orxViewport_CreateFromConfig("Viewport");

  /* Creates soldier */
  pstSoldier = orxObject_CreateFromConfig("Soldier");

  /* Gets main clock */
  pstClock = orxClock_FindFirst(orx2F(-1.0f), orxCLOCK_TYPE_CORE);

  /* Registers our update callback */
  orxClock_Register(pstClock, Update, orxNULL, orxMODULE_ID_MAIN, orxCLOCK_PRIORITY_NORMAL);

  /* Done! */
  return orxSTATUS_SUCCESS;
}

/** Run function
 */
orxSTATUS orxFASTCALL Run()
{
  orxSTATUS eResult = orxSTATUS_SUCCESS;

  /* Should quit? */
  if(orxInput_IsActive("Quit"))
  {
    /* Updates result */
    eResult = orxSTATUS_FAILURE;
  }

  /* Done! */
  return eResult;
}

/** Exit function
 */
void orxFASTCALL Exit()
{
  /* We're a bit lazy here so we let orx clean all our mess! :) */
}

/** Main function
 */
int main(int argc, char **argv)
{
  /* Executes a new instance of tutorial */
  orx_Execute(argc, argv, Init, Run, Exit);

  return EXIT_SUCCESS;
}


#ifdef __orxMSVC__

// Here's an example for a console-less program under windows with visual studio
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
  // Inits and executes orx
  orx_WinExecute(Init, Run, Exit);

  // Done!
  return EXIT_SUCCESS;
}

#endif // __orxMSVC__

This example illustrates a simple animation.  The game loop itself consists of implementing 3 simple functions, Init(), Run() and Exit() for handling various stages of the lifecycle.  The actual game loop itself is the Update callback function which is called continuously as your game is run.  Speaking of which, here is the code running.  The left and right arrow keys toggle between the animations, while up and down scale accordingly.

GIF


Now the “guts” of this example is actually in the ini file containing the data.  Let’s take a look:

[Display]
; In this example, we use the same size for the screen display than our camera's frustum so as to obtain a 1:1 ratio
ScreenWidth   = @Camera.FrustumWidth
ScreenHeight  = @Camera.FrustumHeight
Title         = Anim Tutorial
Smoothing     = false
[Resource]
Texture = ../data/object 

[Input]
SetList = MainInput

[MainInput]
KEY_ESCAPE = Quit

KEY_LEFT   = GoLeft
KEY_RIGHT  = GoRight
KEY_UP     = ScaleUp
KEY_DOWN   = ScaleDown

[Viewport]
Camera = Camera

[Camera]
FrustumWidth  = 640
FrustumHeight = 480
FrustumFar    = 1.0
FrustumNear   = 0.0
Position      = (0.0, 0.0, -1.0)

[Pivot]
Pivot = (15.0, 31.0, 0.0)

[[email protected]]
Texture = soldier.png

[Soldier]
Graphic             = Graphic
AnimationSet        = AnimSet
Scale               = 4.0

[AnimSet]
Direction   = right # down
StartAnim   = IdleRight
KeyDuration = 0.1
Digits      = 1
FrameSize   = (32, 32, 0)

Texture     = soldier_full.png
Pivot       = @Pivot

IdleRight   = 1 ; <= We only want one frame
IdleLeft    = 1
WalkRight   = -1 ; <= We want as many frame that can fit in the texture defined by WalkRight
WalkLeft    = -1

IdleRight-> = IdleRight 
IdleLeft->  = IdleLeft 
WalkRight-> = WalkRight 
WalkLeft->  = WalkLeft 

[IdleLeft]
Flip        = x

[WalkLeft]
Flip        = x

[IdleRight]
Direction   = left

[IdleLeft]
Direction   = left # up

[WalkRight1]
KeyEvent    = !!Left!!

[WalkRight4]
KeyEvent    = !!Right!!

[WalkLeft1]
KeyEvent    = !!Right!!

[WalkLeft4]
KeyEvent    = !!Left!!

As you can see, just about every aspect of the game is data driven here, from the animation names, the source graphic files, to the camera, viewport and even keys pressed and the corresponding binding to call for each key.


This post only scratched the service of how Orx works, but should give you an idea of the data driven approach they have taken.  It certainly wont be for everyone, but it could be a great fit for many people.  If you are interested in giving Orx a shot, be sure to check out our video, which is also embedded below, to walk through the installation process and get you up and running.  Then it’s time to jump into the extremely thorough getting started guide and tutorials available on the Orx website.

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