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# Tutorial 15: Loading Scenes from .irr Files

Since version 1.1, Irrlicht is able to save and load the full scene graph into an .irr file, an xml based format. There is an editor available to edit those files, named irrEdit (http://www.ambiera.com/irredit) which can also be used as world and particle editor. This tutorial shows how to use .irr files.

Lets start: Create an Irrlicht device and setup the window.

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

    using namespace irr;

    #ifdef _MSC_VER
    #pragma comment(lib, "Irrlicht.lib")
    #endif

    int main(int argc, char** argv)
    {
            // ask user for driver
            video::E_DRIVER_TYPE driverType=driverChoiceConsole();
            if (driverType==video::EDT_COUNT)
                    return 1;

            // create device and exit if creation failed

            IrrlichtDevice* device =
                    createDevice(driverType, core::dimension2d<u32>(640, 480));

            if (device == 0)
                    return 1; // could not create selected driver.

            device->setWindowCaption(L"Load .irr file example");

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

Now load our .irr file. .irr files can store the whole scene graph including animators, materials and particle systems. And there is also the possibility to store arbitrary user data for every scene node in that file. To keep this example simple, we are simply loading the scene here. See the documentation at ISceneManager::loadScene and ISceneManager::saveScene for more information. So to load and display a complicated huge scene, we only need a single call to loadScene().

            // load the scene
            if (argc>1)
                    smgr->loadScene(argv[1]);
            else
                    smgr->loadScene("../../media/example.irr");

Now we'll create a camera, and give it a collision response animator that's built from the mesh nodes in the scene we just loaded.

            scene::ICameraSceneNode * camera = smgr->addCameraSceneNodeFPS(0, 50.f, 0.1f);

            // Create a meta triangle selector to hold several triangle selectors.
            scene::IMetaTriangleSelector * meta = smgr->createMetaTriangleSelector();

Now we will find all the nodes in the scene and create triangle selectors for all suitable nodes. Typically, you would want to make a more informed decision about which nodes to performs collision checks on; you could capture that information in the node name or Id.

            core::array<scene::ISceneNode *> nodes;
            smgr->getSceneNodesFromType(scene::ESNT_ANY, nodes); // Find all nodes

            for (u32 i=0; i < nodes.size(); ++i)
            {
                    scene::ISceneNode * node = nodes[i];
                    scene::ITriangleSelector * selector = 0;

                    switch(node->getType())
                    {
                    case scene::ESNT_CUBE:
                    case scene::ESNT_ANIMATED_MESH:
                            // Because the selector won't animate with the mesh,
                            // and is only being used for camera collision, we'll just use an approximate
                            // bounding box instead of ((scene::IAnimatedMeshSceneNode*)node)->getMesh(0)
                            selector = smgr->createTriangleSelectorFromBoundingBox(node);
                    break;

                    case scene::ESNT_MESH:
                    case scene::ESNT_SPHERE: // Derived from IMeshSceneNode
                            selector = smgr->createTriangleSelector(((scene::IMeshSceneNode*)node)->getMesh(), node);
                            break;

                    case scene::ESNT_TERRAIN:
                            selector = smgr->createTerrainTriangleSelector((scene::ITerrainSceneNode*)node);
                            break;

                    case scene::ESNT_OCTREE:
                            selector = smgr->createOctreeTriangleSelector(((scene::IMeshSceneNode*)node)->getMesh(), node);
                            break;

                    default:
                            // Don't create a selector for this node type
                            break;
                    }

                    if(selector)
                    {
                            // Add it to the meta selector, which will take a reference to it
                            meta->addTriangleSelector(selector);
                            // And drop my reference to it, so that the meta selector owns it.
                            selector->drop();
                    }
            }

Now that the mesh scene nodes have had triangle selectors created and added to the meta selector, create a collision response animator from that meta selector.

            scene::ISceneNodeAnimator* anim = smgr->createCollisionResponseAnimator(
                    meta, camera, core::vector3df(5,5,5),
                    core::vector3df(0,0,0));
            meta->drop(); // I'm done with the meta selector now

            camera->addAnimator(anim);
            anim->drop(); // I'm done with the animator now

            // And set the camera position so that it doesn't start off stuck in the geometry
            camera->setPosition(core::vector3df(0.f, 20.f, 0.f));

            // Point the camera at the cube node, by finding the first node of type ESNT_CUBE
            scene::ISceneNode * cube = smgr->getSceneNodeFromType(scene::ESNT_CUBE);
            if(cube)
                    camera->setTarget(cube->getAbsolutePosition());

That's it. Draw everything and finish as usual.

            int lastFPS = -1;

            while(device->run())
            if (device->isWindowActive())
            {
                    driver->beginScene(true, true, video::SColor(0,200,200,200));
                    smgr->drawAll();
                    driver->endScene();

                    int fps = driver->getFPS();

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

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

            }

            device->drop();

            return 0;
    }

| The Irrlicht Engine Documentation © 2003-2010 by Nikolaus Gebhardt. Generated on Sun Oct 24 12:42:00 2010 by Doxygen (1.6.2)