Irrlicht Engine Tutorial

Tutorial 3.CustomSceneNode

This Tutorial is a tutorial for more advanced developers. If you are - currently just playing around with the Irrlicht engine, please look - at other examples first. This tutorial shows how to create a custom - scene node and how to use it in the engine. A custom scene node is needed, - if you want to implement a render technique, the Irrlicht Engine is - currently not supporting. For example you can write a indoor portal - based renderer or a advanced terrain scene node with it. With creating - custom scene nodes, you can easily extend the Irrlicht Engine and adapt - it to your needs.

I will keep the tutorial simple: Keep everything very short, everything - in one .cpp file, and I'll use the engine here as in all other tutorials. - At the end of the tutorial, the result will look like the image below. - This looks not very exciting, but it is a complete customized scene - node and a good point to start from creating you own scene nodes.

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.

Tutorial 3.CustomSceneNode

This Tutorial is a tutorial for more advanced developers. If you are + currently just playing around with the Irrlicht engine, please look + at other examples first. This tutorial shows how to create a custom + scene node and how to use it in the engine. A custom scene node is needed, + if you want to implement a render technique, the Irrlicht Engine is + currently not supporting. For example you can write a indoor portal + based renderer or a advanced terrain scene node with it. With creating + custom scene nodes, you can easily extend the Irrlicht Engine and adapt + it to your needs.

I will keep the tutorial simple: Keep everything very short, everything + in one .cpp file, and I'll use the engine here as in all other tutorials. + At the end of the tutorial, the result will look like the image below. + This looks not very exciting, but it is a complete customized scene + node and a good point to start from creating you own scene nodes.

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.