Irrlicht Engine - A free open source 3d engine

Tutorial 4: Movement
This Tutorial shows how to move and animate SceneNodes. The basic concept of SceneNodeAnimators is shown as well as manual movement of nodes using the keyboard.

The program which is described here will look like this:

Lets start!

As always, I include the header files, use the irr namespace, and tell the linker to link with the .lib file.

#include <stdio.h>
#include <wchar.h>
#include <irrlicht.h>

using namespace irr;

#pragma comment(lib, "Irrlicht.lib")

In this tutorial, one of our goals is to move a scene node using some keys on the keyboard. We store a pointer to the scene node we want to move with the keys here.
The other pointer is a pointer to the Irrlicht Device, which we need int the EventReceiver to manipulate the scene node and to get the active camera.

scene::ISceneNode* node = 0;
IrrlichtDevice* device = 0;

To get events like mouse and keyboard input, or GUI events like "the OK button has been clicked", we need an object wich is derived from the IEventReceiver object. There is only one method to override: OnEvent. This method will be called by the engine when an event happened. We will use this input to move the scene node with the keys W and S.

class MyEventReceiver : public IEventReceiver
{
public:
	virtual bool OnEvent(SEvent event)
	{

If the key 'W' or 'S' was left up, we get the position of the scene node, and modify the Y coordinate a little bit. So if you press 'W', the node moves up, and if you press 'S' it moves down.

	if (node != 0 && event.EventType == irr::EET_KEY_INPUT_EVENT &&
				!event.KeyInput.PressedDown)
	{
			switch(event.KeyInput.Key)
			{
			case KEY_KEY_W:
			case KEY_KEY_S:
				{
					core::vector3df v = node->getPosition();
					v.Y += event.KeyInput.Key == KEY_KEY_W ? 2.0f : -2.0f;
					node->setPosition(v);
				}
				return true;
			}
	}


	return false;
	}
};

The event receiver for moving a scene node is ready. So lets just create an Irrlicht Device and the scene node we want to move. We also create some other additional scene nodes, to show that there are also some different possibilities to move and animate scene nodes.

int main()
{
   MyEventReceiver receiver;

   

  device = createDevice(video::EDT_OPENGL, core::dimension2d<s32>(640, 480),

       16, false, false, false, &receiver);

   video::IVideoDriver* driver = device->getVideoDriver();

   scene::ISceneManager* smgr = device->getSceneManager();

Create the node for moving it with the 'W' and 'S' key. We create a 'test node', which is a cube built in into the engine for testing purposes. We place the node a (0,0,30) and we assign a texture to it to let it look a little bit more interesting.

node = smgr->addTestSceneNode();
node->setPosition(core::vector3df(0,0,30));
node->setMaterialTexture(0, driver->getTexture("../../media/wall.bmp"));

Now we create another node, moving using a scene node animator. Scene node animators modify scene nodes and can be attached to any scene node like
mesh scene nodes, billboards, lights and even camera scene nodes. Scene node animators are not only able to modify the position of a scene node, they can
also animate the textures of an object for example. We create a test scene node again an attach a 'fly circle' scene node to it, letting this node fly around our first test scene node.

scene::ISceneNode* n = smgr->addTestSceneNode();
n->setMaterialTexture(0, driver->getTexture("../../media/t351sml.jpg"));

scene::ISceneNodeAnimator* anim = 

     smgr->createFlyCircleAnimator(core::vector3df(0,0,30), 20.0f);

n->addAnimator(anim);

anim->drop();

The last scene node we add to show possibilities of scene node animators is a md2 model, which uses a 'fly straight' animator to run between to points.

scene::IAnimatedMeshSceneNode* anms = smgr->addAnimatedMeshSceneNode(
		smgr->getMesh("../../media/sydney.md2"));



if (n)
	{
		anim = smgr->createFlyStraightAnimator(core::vector3df(100,0,60), 
			core::vector3df(-100,0,60), 10000, true);
		anms->addAnimator(anim);
		anim->drop();

To make to model look better, we disable lighting (we have created no lights, and so the model would be black), set the frames between which the animation should loop, rotate the model around 180 degrees, and adjust the animation speed
and the texture.
To set the right animation (frames and speed), we would also be able to just call "anms->setMD2Animation(scene::EMAT_RUN)" for the 'run' animation instead of "setFrameLoop" and "setAnimationSpeed", but this only works with MD2 animations, and so you know how to start other animations.

   anms->setMaterialFlag(video::EMF_LIGHTING, false);
   anms->setFrameLoop(320, 360);

   anms->setAnimationSpeed(30);
   anms->setRotation(core::vector3df(0,180.0f,0));
   anms->setMaterialTexture(0, driver->getTexture("../../media/sydney.BMP"));
}

To be able to look at and move around in this scene, we create a first person shooter style camera and make the mouse cursor invisible.

smgr->addCameraSceneNodeFPS(0, 100.0f, 100.0f);
device->getCursorControl()->setVisible(false);

We have done everything, so lets draw it. We also write the current frames per second and the name of the driver to the caption of the window.

int lastFPS = -1;

while(device->run())

{

     driver->beginScene(true, true, video::SColor(255,90,90,156));

     smgr->drawAll();

     driver->endScene();

     int fps = driver->getFPS();

     if (lastFPS != fps)

     {

        wchar_t tmp[1024];

        swprintf(tmp, 1024, L"Movement Example - Irrlicht Engine (%s)(fps:%d)",
        driver->getName(), fps);

       device->setWindowCaption(tmp);

       lastFPS = fps;

     }

}



device->drop();
return 0;
}

That's it. Compile and play around with the program.