Irrlicht簡介

Irrlicht在國內也被叫做“鬼火”引擎，是一款用C++編寫的開放原始碼的高效能遊戲引擎。而且是跨平臺的，具有很好的移植性，Irrlicht支援OpenGl、Direcx3D渲染，引擎本身也實現了一套自己的渲染系統。在商業引擎中能夠找到的藝術特性，Irrlicht基本都支援。目前有很多專案中都使用到它，Irrlicht社群也比較活躍，可以在網際網路上找到不少Irrlicht增強工具，例如irrEdit、irrKlang等。在眾多開源遊戲引擎中，Irrlicht也是比較受筆者青睞的一款。

Irrlicht下載與使用

Irrlicht目前最新穩定版本為1.8.1，專案釋出在sourceforge平臺上，使用者可以通過sourceforge網站首頁面搜尋功能找到Irrlicht專案下載地址，或者從Irrlicht官網獲取下載連結。

1.目錄結構

解壓後目錄結構如下：

bin：不同平臺編譯Irrlicht生成的可執行檔案和動態庫檔案放在該目錄中。
doc : 該目錄中為Irrlicht API文件。
examples ： Irrlicht官方提供的案例程式存放在該目錄中。
include ： 存放引擎所有標頭檔案。
lib : 該目錄存放Irrlicht引擎編譯過後生成的靜態庫。
media ： 官方案例所需資原始檔存放在此目錄中。
source ： 存放引擎原始碼。
tools : 該目錄下為Irrlicht引擎相關工具。如irrEdit、GUIEditor等。

2.官方案例

Irrlicht使用起來是非常方便的，這也是筆者比較喜歡它的原因之一。為了方便使用者學習和使用引擎，Irrlicht官方提供了大量的例子程式，而且都比較具有代表性。

開啟examples目錄，Irrlicht已經為目前主流開發工具Windows平臺下Visual Studio、MacOS下的Xcode以及Linux平臺下的GNU MAKE做好了專案配置。

筆者是在Windows作業系統下使用VS2012進行演示，雙擊BuildAllExamples_vc11.sln開啟解決方案，無需做任何配置即可編譯執行程式。

編譯執行Collision案例程式：

看起來效果是不是很炫呢?Irrlicht為我們做了大量的封裝，即便看似如此複雜的程式，實際程式碼不超過200行。

#include <irrlicht.h>
#include "driverChoice.h"
 


using namespace irr;

#ifdef _MSC_VER
#pragma comment(lib, "Irrlicht.lib")
#endif
enum
{   
    ID_IsNotPickable = 0,
    IDFlag_IsPickable = 1 << 0,
    IDFlag_IsHighlightable = 1 << 1
};
int main()
{
    video::E_DRIVER_TYPE driverType=video::EDT_OPENGL;//driverChoiceConsole();
    if (driverType==video::EDT_COUNT)
        return 1;

    IrrlichtDevice *device =
        createDevice(driverType, core::dimension2d<u32>(1024, 768), 16, false);
    if (device == 0)
        return 1; // could not create selected driver.

    video::IVideoDriver* driver = device->getVideoDriver();
    scene::ISceneManager* smgr = device->getSceneManager();

    device->getFileSystem()->addFileArchive("../../media/map-20kdm2.pk3");

    scene::IAnimatedMesh* q3levelmesh = smgr->getMesh("20kdm2.bsp");
    scene::IMeshSceneNode* q3node = 0;

    if (q3levelmesh)
        q3node = smgr->addOctreeSceneNode(q3levelmesh->getMesh(0), 0, IDFlag_IsPickable);
    scene::ITriangleSelector* selector = 0;

    if (q3node)
    {
        q3node->setPosition(core::vector3df(-1350,-130,-1400));

        selector = smgr->createOctreeTriangleSelector(
                q3node->getMesh(), q3node, 128);
        q3node->setTriangleSelector(selector);
    }

    scene::ICameraSceneNode* camera =
        smgr->addCameraSceneNodeFPS(0, 100.0f, .3f, ID_IsNotPickable, 0, 0, true, 3.f);
    camera->setPosition(core::vector3df(50,50,-60));
    camera->setTarget(core::vector3df(-70,30,-60));

    if (selector)
    {
        scene::ISceneNodeAnimator* anim = smgr->createCollisionResponseAnimator(
            selector, camera, core::vector3df(30,50,30),
            core::vector3df(0,-10,0), core::vector3df(0,30,0));
        selector->drop(); // As soon as we're done with the selector, drop it.
        camera->addAnimator(anim);
        anim->drop();  
    }

    device->getCursorControl()->setVisible(false);

    scene::IBillboardSceneNode * bill = smgr->addBillboardSceneNode();
    bill->setMaterialType(video::EMT_TRANSPARENT_ADD_COLOR );
    bill->setMaterialTexture(0, driver->getTexture("../../media/particle.bmp"));
    bill->setMaterialFlag(video::EMF_LIGHTING, false);
    bill->setMaterialFlag(video::EMF_ZBUFFER, false);
    bill->setSize(core::dimension2d<f32>(20.0f, 20.0f));
    bill->setID(ID_IsNotPickable); // This ensures that we don't accidentally ray-pick it

    scene::IAnimatedMeshSceneNode* node = 0;

    video::SMaterial material;

    node = smgr->addAnimatedMeshSceneNode(smgr->getMesh("../../media/faerie.md2"),
                        0, IDFlag_IsPickable | IDFlag_IsHighlightable);
    node->setPosition(core::vector3df(-90,-15,-140)); // Put its feet on the floor.
    node->setScale(core::vector3df(1.6f)); // Make it appear realistically scaled
    node->setMD2Animation(scene::EMAT_POINT);
    node->setAnimationSpeed(20.f);
    material.setTexture(0, driver->getTexture("../../media/faerie2.bmp"));
    material.Lighting = true;
    material.NormalizeNormals = true;
    node->getMaterial(0) = material;

    selector = smgr->createTriangleSelector(node);
    node->setTriangleSelector(selector);
    selector->drop(); // We're done with this selector, so drop it now.
    node = smgr->addAnimatedMeshSceneNode(smgr->getMesh("../../media/ninja.b3d"),
                        0, IDFlag_IsPickable | IDFlag_IsHighlightable);
    node->setScale(core::vector3df(10));
    node->setPosition(core::vector3df(-75,-66,-80));
    node->setRotation(core::vector3df(0,90,0));
    node->setAnimationSpeed(8.f);
    node->getMaterial(0).NormalizeNormals = true;
    node->getMaterial(0).Lighting = true;
    selector = smgr->createTriangleSelector(node);
    node->setTriangleSelector(selector);
    selector->drop();

    node = smgr->addAnimatedMeshSceneNode(smgr->getMesh("../../media/dwarf.x"),
                        0, IDFlag_IsPickable | IDFlag_IsHighlightable);
    node->setPosition(core::vector3df(-70,-66,-30)); // Put its feet on the floor.
    node->setRotation(core::vector3df(0,-90,0)); // And turn it towards the camera.
    node->setAnimationSpeed(20.f);
    node->getMaterial(0).Lighting = true;
    selector = smgr->createTriangleSelector(node);
    node->setTriangleSelector(selector);
    selector->drop();

    node = smgr->addAnimatedMeshSceneNode(smgr->getMesh("../../media/yodan.mdl"),
                        0, IDFlag_IsPickable | IDFlag_IsHighlightable);
    node->setPosition(core::vector3df(-90,-25,20));
    node->setScale(core::vector3df(0.8f));
    node->getMaterial(0).Lighting = true;
    node->setAnimationSpeed(20.f);

    // Just do the same as we did above.
    selector = smgr->createTriangleSelector(node);
    node->setTriangleSelector(selector);
    selector->drop();

    material.setTexture(0, 0);
    material.Lighting = false;
    scene::ILightSceneNode * light = smgr->addLightSceneNode(0, core::vector3df(-60,100,400),
        video::SColorf(1.0f,1.0f,1.0f,1.0f), 600.0f);
    light->setID(ID_IsNotPickable); // Make it an invalid target for selection.

    scene::ISceneNode* highlightedSceneNode = 0;
    scene::ISceneCollisionManager* collMan = smgr->getSceneCollisionManager();
    int lastFPS = -1;
    material.Wireframe=true;
    while(device->run())
    if (device->isWindowActive())
    {
        driver->beginScene(true, true, 0);
        smgr->drawAll();
        if (highlightedSceneNode)
        {
            highlightedSceneNode->setMaterialFlag(video::EMF_LIGHTING, true);
            highlightedSceneNode = 0;
        }

        core::line3d<f32> ray;
        ray.start = camera->getPosition();
        ray.end = ray.start + (camera->getTarget() - ray.start).normalize() * 1000.0f;

        core::vector3df intersection;
        core::triangle3df hitTriangle;

        scene::ISceneNode * selectedSceneNode =
            collMan->getSceneNodeAndCollisionPointFromRay(
                    ray,
                    intersection, 
                    hitTriangle, 
                    IDFlag_IsPickable, 
                    0);     
        if(selectedSceneNode)
        {
            bill->setPosition(intersection);
            driver->setTransform(video::ETS_WORLD, core::matrix4());
            driver->setMaterial(material);
            driver->draw3DTriangle(hitTriangle, video::SColor(0,255,0,0));

            if((selectedSceneNode->getID() & IDFlag_IsHighlightable) == IDFlag_IsHighlightable)
            {
                highlightedSceneNode = selectedSceneNode;
                highlightedSceneNode->setMaterialFlag(video::EMF_LIGHTING, false);
            }
        }
        driver->endScene();

        int fps = driver->getFPS();

        if (lastFPS != fps)
        {
            core::stringw str = L"Collision detection example - Irrlicht Engine [";
            str += driver->getName();
            str += "] FPS:";
            str += fps;

            device->setWindowCaption(str.c_str());
            lastFPS = fps;
        }
    }
    device->drop();

    return 0;
}