Irrlicht Engine Tutorial

To start, I include the header files, use the irr namespace, and tell + the linker to link with the .lib file.

+ + + + +

#include <irrlicht.h>

using namespace irr;

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

Here comes the most sophisticated part of this tutorial: The class + of our very own custom scene node. To keep it simple,
+ our scene node will not be an indoor portal renderer nor a terrain scene + node, but a simple tetraeder, a 3d object consiting of 4 connected vertices, + which only draws itself and does nothing more.

To let our scene node be able to be inserted into the Irrlicht Engine + scene, the class we create needs only be derived from the ISceneNode + class and has to override some methods.

+ + + + +

class CSampleSceneNode : public scene::ISceneNode
{

First, we declare some member variables, to hold data for our tetraeder: + The bounding box, 4 vertices, and
+ the material of the tetraeder.

+ + + + +

core::aabbox3d<f32> Box;
video::S3DVertex Vertices[4];
video::SMaterial Material;

The parameters of the constructor specify the parent of the scene node, + a pointer to the scene manager, and an id of the scene node. In the + constructor itself, we call the parent classes constructor, set some + properties of the material we use to draw the scene node and create + the 4 vertices of the tetraeder we will draw later.

+ + + + +

public:

CSampleSceneNode(scene::ISceneNode* parent, scene::ISceneManager* mgr, s32 id)
+ : scene::ISceneNode(parent, mgr, id)
+{ 
+  Material.Wireframe = false;
+  Material.Lighting = false;

  Vertices[0] = video::S3DVertex(0,0,10, 1,1,0,video::SColor(255,0,255,255),0,1);
+  Vertices[1] = video::S3DVertex(10,0,-10, 1,0,0,video::SColor(255,255,0,255),1,1); 
+  Vertices[2] = video::S3DVertex(0,20,0, 0,1,1,video::SColor(255,255,255,0),1,0);
+  Vertices[3] = video::S3DVertex(-10,0,-10, 0,0,1,video::SColor(255,0,255,0),0,0);
+

+
+ The Irrlicht Engine needs to know the bounding box of your scene node. + It will use it for doing automatic culling and other things. Hence we + need to create a bounding box from the 4 vertices we use. If you do not + want the engine to use the box for automatic culling, and/or don't want + to create the box, you could also write
+ AutomaticCullingEnabled = false;.
+
+ + + + +

  Box.reset(Vertices[0].Pos);
 		for (s32 i=1; i<4; ++i)
 			Box.addInternalPoint(Vertices[i].Pos);
+}

+
+

Before it is drawn, the OnPreRender() method of every scene node in + the scene is called by the scene manager. If the scene node wishes to + draw itself, it may register itself in the scene manager to be drawn. + This is necessary to tell the scene manager when it should call the + ::render method. For example normal scene nodes render their content + one after another, while stencil buffer shadows would like to be drawn + after all other scene nodes. And camera or light scene nodes need to + be rendered before all other scene nodes (if at all).
+ So here we simply register the scene node to get rendered normally. + If we would like to let it be rendered like cameras or light, we would + have to call SceneManager->registerNodeForRendering(this, SNRT_LIGHT_AND_CAMERA); +
+ After this, we call the OnPreRender-method of the base class ISceneNode, + which simply lets also all the child scene nodes of this node register + themselves.

In the render() method most of the interresting stuff happenes: The Scene + node renders itself. We override this method and draw the tetraeder.

At least, we create three small additional methods. GetBoundingBox() + returns the bounding box of this scene node,
+ GetMaterialCount() returns the amount of materials in this scene node + (our tetraeder only has one material), and getMaterial() returns the material + at an index. Because we have only one material here, we can return the + only one material, assuming that no one ever calls getMaterial() with + an index greater than 0.

That's it. The Scene node is done. Now we simply have to start the engine, + create the scene node and a camera, and look at the result.

Create our scene node. Note that it is dropped (->drop()) instantly + after we create it. This is possible because the scene manager now takes + care of it. This is not nessecary, it would also be possible to drop it + at the end of the program.

To animate something in this boring scene consisting only of one tetraeder, + and to show, that you now can use your scene node like any other scene + node in the engine, we add an animator to the scene node, which rotates + the node a little bit.