http://www.developer.com/net/cplus/article.php/3529571/Cross-Platform-Game-Development-for-C-Developers-Part-III-The-3D-Irrlicht-Engine.htm
The Irrlicht Engine is a high-performance, real-time 3D engine written and usable in C++ and also available for .NET languages. It is completely cross-platform, using your choice of Direct3D on Windows, OpenGL 1.2, or its own software renderer. Although open source, the Irrlicht library offers state-of-the-art features normally found in commercial 3D engines, such as dynamic shadows, particle systems, character animation, indoor and outdoor technology, and collision detection (see Figure 1). Figure 1. The Irrlicht 3D Engine Irrlicht is the name of a German fairy-tale creature that glows and flies, and can be found mostly in the vicinity of swamps. The word "Irrlicht" is the combination of the two German words: "irr," meaning mad; and "Licht," meaning "light." In English, it translates to "will-o'-the-wisp." Irrlicht is also blessed with a huge, active development community with lots of projects. Yet, because Irrlicht is primarily the work of gaming auteur Nikolaus Gebhardt, it reflects a very cohesive design. You can find enhancements for Irrlicht all over the Web, such as alternative terrain renderers, portal renderers, exporters, world layers, tutorials, and editors. Also, it has independently created language bindings for Java, Perl, Ruby, BASIC, Python, LUA, and more. And best of all: It's completely free. Before drilling down into the API, let me get a bit more specific about what Irrlicht has to offer the 3D game developer: Figure 2: Irrlicht-based game called Yet Another Space Shooter (YASS) displays breathtakingly good rendering for a static game frame I always like to show off just a little bit more than "hello world" when I'm demo-ing a new game engine. In this example, I'll show how to use stencil buffer shadows, the particle system, billboards, dynamic light, and the water surface scene node—all at the same time (see Figure 3). Figure 3. Render This Scene with Dynamic Light and Water The Irrlicht Engine automatically checks to see whether your hardware supports the stencil buffer, and disables shadows if it's not present. In this demo, the 'shadows' flag in createDevice() is set to render a dynamic shadow cast from an animated character. If this example runs too slowly on your PC, set it to false or buy a better graphics card. To be able to use the Irrlicht.DLL file, you need to link with the Irrlicht.lib. You could set this option in the project settings, but to make it easy, use a pragma comment. The createDevice() instantiates the root object for doing everything with the engine. Parameters are as follows: For the example environment, you'll load a 3D Studio Max file of a room. The room is nothing much to look at, but the Irrlicht Engine is able to create a cool texture mapping for you. Just use the mesh manipulator and create a planar texture mapping for the mesh: I wasn't happy with the emissive light color from this import file. The following shows how to implement these steps: The first special effect you will add is water animation. To do this, the WaterSurfaceSceneNode takes a mesh as input and makes it wave like a water surface. If you let this scene node use a nice material like the MT_REFLECTION_2_LAYER, it looks really cool: As input mesh, you create a hilly plane mesh, but you could use any other mesh for this. You could even re-use the room.3ds input file (which would look really strange). The example also paints all the other surfaces with a generic stone texture pattern. The second special effect is very basic but highly useful: a transparent billboard combined with a dynamic light. To make this happen, you simply create a light scene node, let it fly around, and, to make it look cooler, attach a billboard scene node to it:
The next special effect is a lot more interesting: a particle system. The particle system in the Irrlicht Engine is both modular and extensible, yet still easy to use. You simply put the particle emitters into a particle system scene node and thus the particles seem to appear from nothing. These emitters are quite configurable and usually have lots of parameters like particle direction, amount, and color. Of course, emitter types differ (for example, a point emitter that lets particles pop out at a fixed point). If the particle emitters available in the engine are not enough for you, you can easily create your own. Simply derive a new class from the IParticleEmitter interface and attach it to the particle system using setEmitter(). The next example creates a box particle emitter. As you might expect, it creates particles randomly inside a bounding box. The parameters define the box, direction of the particles, minimal and maximal new particles per second, color, and minimal and maximal lifetime of the particles. A particle system composed entirely of emitters would be both boring and lacking in realism. Therefore, Irrlicht supports particle affectors, which modify particles as they fly around. Once added to the particle system, they can simulate additional effects like gravity or wind. The particle affector in this example simply modifies the color of the particles to produce a fade-out effect. As you might have guessed, particle affectors are implemented by deriving from IParticleAffector and adding them with addAffector(). After you set a nice material to the particle system, you have a cool-looking campfire. By adjusting material, texture, and particle emitter and affector parameters, you also can easily create smoke, rain, explosions, snow, and so on: Last but not least, you want a dynamic shadow cast from an animated character. For this, you load a Quake2 .md2 model file and place it into your world. To create the shadow, you just call addShadowVolumeSceneNode(). You control the color of shadows, which is adjustable only globally and affects all shadows, by calling ISceneManager::setShadowColor(). Voilà! Here is your dynamic shadow: Finally, you can enter the game loop controlled by the device->run() method. The loop will run until the device quits by getting a close window event (such as the ALT-F4 keystroke in Windows). Everything must be drawn between a beginScene() and an endScene() call. The beginScene() clears the screen with a color and also the depth buffer, if desired. Then you let the Scene Manager and the GUI environment draw their content. With the endScene() call, everything is presented on the screen. In this example, you also dynamically display the frames per second (FPS) figure, which is all-important to the serious gamer, on the titlebar: After you have finished, you must delete the Irrlicht Device created earlier with createDevice(). With the Irrlicht Engine, you should delete all objects you created with a method or function that starts with 'create'. The object is deleted simply by calling device->drop(). As mentioned in the introduction, Irrlicht has a thriving community of independent developers producing add-ons and games. Many improvements by these people are re-integrated into a subsequent Irrlicht release. Here's a brief list of a few I thought would interest prospective developers: Be sure to come back next week for Cross-Platform Game Development for C++ Developers, Part IV. Victor Volkman has been writing for C/C++ Users Journal and other programming journals since the late 1980s. He is a graduate of Michigan Tech and a faculty advisor board member for Washtenaw Community College CIS department. Volkman is the editor of numerous books, including C/C++ Treasure Chest and is the owner of Loving Healing Press. He can help you in your quest for open source tools and libraries, just drop an e-mail to sysop@HAL9K.com.
Cross-Platform Game Development for C++ Developers, Part III: The 3D Irrlicht Engine
August 24, 2005
Inside the Irrlicht Feature Set
Click here for a larger image. Special Effects in Irrlicht
#include <irrlicht.h>
#include <iostream>
using namespace irr;
#pragma comment(lib, "Irrlicht.lib")
int main()
{
// Let's assume the user wants OpenGL for this example
// could have specified DirectX 8, 9, etc.
video::E_DRIVER_TYPE driverType = video::EDT_OPENGL;
// create device and exit if creation failed
IrrlichtDevice *device = createDevice(driverType,
core::dimension2d
scene::IAnimatedMesh* mesh = smgr->getMesh("room.3ds");
smgr->getMeshManipulator()->makePlanarTextureMapping(
mesh->getMesh(0), 0.008f);
scene::ISceneNode* node = 0;
node = smgr->addAnimatedMeshSceneNode(mesh);
node->setMaterialTexture(0, driver->getTexture("wall.jpg"));
node->getMaterial(0).EmissiveColor.set(0,0,0,0);
Water Animation
mesh = smgr->addHillPlaneMesh("myHill",
core::dimension2d
Transparent Billboard and Light
// create light
node = smgr->addLightSceneNode(0, core::vector3df(0,0,0),
video::SColorf(1.0f, 0.6f, 0.7f, 1.0f), 600.0f);
scene::ISceneNodeAnimator* anim = 0;
anim = smgr->createFlyCircleAnimator(core::vector3df(0,150,0),
250.0f);
node->addAnimator(anim);
anim->drop();
// attach billboard to light
node = smgr->addBillboardSceneNode(node, core::dimension2d
Particle System
scene::IParticleSystemSceneNode* ps = 0;
ps = smgr->addParticleSystemSceneNode(false);
ps->setPosition(core::vector3df(-70,60,40));
ps->setScale(core::vector3df(2,2,2));
ps->setParticleSize(core::dimension2d
Shadow Cast
mesh = smgr->getMesh("../../media/faerie.md2");
scene::IAnimatedMeshSceneNode* anode = 0;
anode = smgr->addAnimatedMeshSceneNode(mesh);
anode->setPosition(core::vector3df(-50,45,-60));
anode->setMD2Animation(scene::EMAT_STAND);
anode->setMaterialTexture(0, driver->getTexture
("../../media/Faerie5.BMP"));
anode->addShadowVolumeSceneNode();
smgr->setShadowColor(video::SColor(220,0,0,0));
Game Loop
scene::ICameraSceneNode* camera = smgr->addCameraSceneNodeFPS();
camera->setPosition(core::vector3df(-50,50,-150));
int lastFPS = -1;
while(device->run())
{
driver->beginScene(true, true, 0);
smgr->drawAll();
driver->endScene();
int fps = driver->getFPS();
if (lastFPS != fps)
{
core::stringw str = L"Campfire FX example [";
str += driver->getName();
str += "] FPS:";
str += fps;
device->setWindowCaption(str.c_str());
lastFPS = fps;
}
}
device->drop();
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Stay Tuned!
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