History: MadMarx Tutorial 5

Source of version: 9 (current)

!Foreword.
If you prefer tutorials that come with a framework => check the other wiki tutorial series.
If you prefer tutorials that go step by step without a framework => this page should be ok.

I assume you know C++. If not, this tutorial will probably be hard to understand !

This tutorial presents only a few elements of Ogre3D.

You can download the code and media for this tutorial at the bottom of this wiki page.
This little tutorial is an extract of a bigger project which contains more tutorials & helper classes.
This bigger project is avaible there : 
https://sourceforge.net/projects/so3dtools/

Also, make sure you read these tutorials in order!

{maketoc}

!!Tutorial Description
In this program a .mesh file will be loaded from the hard drive disk.

In this basic version, I will load everything that lies in a directory.
When loading loadable data with ogre3D, the 'ogre3D way' to do it is to
1/ create a ResourceGroup.
2/ declare the path of the directory containing the resource you want in that ResourceGroup.
3/ initialise and load the ResourceGroup.
There are other ways to do it, some are covered in other tutorials.

How to get a .mesh file? You can code a program to do it, or use Blender / 3DSMAX / Maya / ...
that will export (using plugins) either a .mesh, either a .xml that can be converted
to a .mesh. (Note : the 'dtd' of this xml + the OgreXMLConverter program sources are in
the source of ogre3D : Tools/XMLConverter/docs).

!!After viewport creation
Here I choose a name for a resource group. Then I create it.
Often, a resourcegroup is a good way to store the data corresponding
to a level in a game.

{CODE(wrap="1",colors="c++")} 
¤	Ogre::String lNameOfResourceGroup = "Mission 1 : Deliver Tom";
	{
		Ogre::ResourceGroupManager& lRgMgr = Ogre::ResourceGroupManager::getSingleton();
		lRgMgr.createResourceGroup(lNameOfResourceGroup);
{CODE} 
We say which directories will be loaded by this resourcegroup.
I can add many directories, which will be loaded in same the ORDER.
This ORDER is extremely important : if a ((-Material|material)) is loaded <i>after</i> a mesh using this ((-Material|material)),
this mesh won't be able to find the ((-Material|material)) during its loading!
I advise you not to use a recursive load (which load the full directory tree).
Seriously, 'recursive loading' often leads to problems.

{CODE(wrap="1",colors="c++")} 
¤		Ogre::String lDirectoryToLoad = "../../media/mesh";
		bool lIsRecursive = false;
		lRgMgr.addResourceLocation(lDirectoryToLoad, "FileSystem", lNameOfResourceGroup, lIsRecursive);
{CODE} 
The function 'initialiseResourceGroup' parses scripts if any in the locations.

{CODE(wrap="1",colors="c++")} 
¤		lRgMgr.initialiseResourceGroup(lNameOfResourceGroup);
{CODE} 
Files that can be loaded are loaded.

{CODE(wrap="1",colors="c++")} 
¤		lRgMgr.loadResourceGroup(lNameOfResourceGroup);
{CODE} 
Now the loaded ((-Mesh|Mesh)) is available from its ResourceGroup,
as well as from the Ogre::MeshManager. A shared pointer to
it can be accessed by : Ogre::MeshManager::getSingleton().getByName(name_of_the_mesh);

Now I can create Entities using that mesh.

{CODE(wrap="1",colors="c++")} 
¤		Ogre::String lNameOfTheMesh = "MonsterHead.mesh";
		int lNumberOfEntities = 5;
		for(int iter = 0; iter < lNumberOfEntities; ++iter)
		{
			Ogre::Entity* lEntity = lScene->createEntity(lNameOfTheMesh);
{CODE} 
Now I attach it to a scenenode, so that it becomes present in the scene.

{CODE(wrap="1",colors="c++")} 
¤			Ogre::SceneNode* lNode = lRootSceneNode->createChildSceneNode();
			lNode->attachObject(lEntity);
{CODE} 
I move the ((-SceneNode|SceneNode)) so that it is visible to the ((-Camera|camera)).

{CODE(wrap="1",colors="c++")} 
¤			float lPositionOffset = float(1+ iter * 2) - (float(lNumberOfEntities));
			lPositionOffset = lPositionOffset * 20;
			lNode->translate(lPositionOffset, lPositionOffset, -200.0f);
{CODE} 
The loaded mesh will be white. This is normal.


! main.cpp 
{CODE(wrap="1",colors="c++")} 
// In this program a .mesh file will be loaded from the hard drive disk.
// 
// In this basic version, I will load everything that lies in a directory.
// When loading loadable data with ogre3D, the 'ogre3D way' to do it is to 
// 1/ create a ResourceGroup.
// 2/ declare the path of the directory containing the resource you want in that ResourceGroup.
// 3/ initialise and load the ResourceGroup.
// There are other ways to do it, some are covered in other tutorials.
//
// How to get a .mesh file? You can code a program to do it, or use Blender / 3DSMAX / Maya / ...
// that will export (using plugins) either a .mesh, either a .xml that can be converted 
// to a .mesh. (Note : the 'dtd' of this xml + the OgreXMLConverter program sources are in 
// the source of ogre3D : Tools/XMLConverter/docs).

// I will use std::auto_ptr so I need to include 'memory'. 
// If you don't know std::auto_ptr, you should check some C++ tutorials/lesson on this matter.
#include <memory>
// I will check for std::exception. If you don't know what exception/try/catch means, you should learn C++ first.
#include <exception>

// These are some files that we need to include to use Ogre3D. Note that you can at the beginnings use directly "Ogre.h", to include lots of commonly used classes.
#include "OGRE/OgreRoot.h"
#include "OGRE/OgreRenderSystem.h"
#include "OGRE/OgreRenderWindow.h"
#include "OGRE/OgreWindowEventUtilities.h"
#include "OGRE/OgreManualObject.h"
#include "OGRE/OgreEntity.h"

//Here I include my other files, like the one for SimpleOgreInit...
#include "SimpleOgreInit.h"

#include "EasyDefines.h"

// I declare a function in which I will make my whole application.
// This is easy then to add more things later in that function.
// The main will call this function and take care of the global try/catch.
void AnOgreApplication()
{
	// I construct my object that will allow me to initialise Ogre easily.
	OgreEasy::SimpleOgreInit lOgreInit;

	if(!lOgreInit.initOgre())
	{
		std::cout<<"Impossible to init Ogre correctly."<<std::endl;
		return;
	}

	//I prefer to be able to access my variables directly.
	Ogre::Root* lRoot = lOgreInit.mRoot.get();
	Ogre::RenderWindow* lWindow = lOgreInit.mWindow;

	// I create a scenemanager. This is like a 'Scene', in which I can put lights, 3d objects, etc...
	// The scenemanager contains an arborescent graph of 'SceneNodes'. To manage elements of the scene,
	// I will create SceneNodes in the SceneManager, and attach the elements to the scenenodes.
	// First parameter : I select a kind of SceneManager. This may have a huge impact on performance.
	// Depending on your scene, some are better than other. The default one does no optimization at all.
	// Second parameter : I give a name to the scenemanager.
	// Note : It is easy to have more than one scenemanager (If you got 2 different scenes for example).
	Ogre::SceneManager* lScene = lRoot->createSceneManager(Ogre::ST_GENERIC, "MyFirstSceneManager");

	// The 'root SceneNode' is the only scenenode at the beginning in the SceneManager.
	// The SceneNodes can be seen as 'transformation' containers <=> it contains scale/position/rotation
	// of the objects. There is only 1 root scenenode, and all other scenenode are 
	// its direct or indirect children.
	Ogre::SceneNode* lRootSceneNode = lScene->getRootSceneNode();

	// I create a camera. It represent a 'point of view' in the scene.
	Ogre::Camera* lCamera = lScene->createCamera("MyFirstCamera");

	// I attach the camera to a new SceneNode. It will be easier then to move it in the scene.
	Ogre::SceneNode* lCameraNode = lRootSceneNode->createChildSceneNode("MyFirstCameraNode");
	lCameraNode->attachObject(lCamera);

	// We create a viewport on a part of the window.
	// A viewport is the link between 1 camera and 1 drawing surface (here the window).
	// I can then call 'update();' on it to make it draw the Scene from the camera.
	// You can have several viewports on 1 window.
	// Check API for details on parameters.
	float lViewportWidth = 0.88f;
	float lViewportHeight = 0.88f;
	float lViewportLeft	= (1.0f - lViewportWidth) * 0.5f;
	float lViewportTop = (1.0f - lViewportHeight) * 0.5f;
	unsigned short lMainViewportZOrder = 100;
	Ogre::Viewport * vp = lWindow->addViewport(lCamera, lMainViewportZOrder, lViewportLeft, lViewportTop, lViewportWidth, lViewportHeight);

	// I want the viewport to draw the scene automatically
	// when I will call lWindow->update();
	vp->setAutoUpdated(true);

	// I choose a color for this viewport. 
	// I prefer to have a bright color, to detect holes in geometry etc...
	vp->setBackgroundColour(Ogre::ColourValue(1,0,1));

	// I choose the visual ratio of the camera. To make it looks real, I want it the same as the viewport.
	float ratio = float(vp->getActualWidth()) / float(vp->getActualHeight());
	lCamera->setAspectRatio(ratio);

	// I choose the clipping far& near planes. if far/near>2000, you can get z buffer problem.
	// eg : far/near = 10000/5 = 2000 . it's ok.
	// If (far/near)>2000 then you will likely get 'z fighting' issues.
	lCamera->setNearClipDistance(1.5f);
	lCamera->setFarClipDistance(3000.0f); 

	// I want my window to be active
	lWindow->setActive(true);

	// I want to update myself the content of the window, not automatically.
	lWindow->setAutoUpdated(false);

	// Here I choose a name for a resource group. Then I create it.
	// Often, a resourcegroup is a good way to store the data corresponding
	// to a level in a game.
	Ogre::String lNameOfResourceGroup = "Mission 1 : Deliver Tom";
	{
		Ogre::ResourceGroupManager& lRgMgr = Ogre::ResourceGroupManager::getSingleton();
		lRgMgr.createResourceGroup(lNameOfResourceGroup);

		// We say which directories will be loaded by this resourcegroup.
		// I can add many directories, which will be loaded in same the ORDER.
		// This ORDER is extremely important : if a material is loaded <i>after</i> a mesh using this material,
		// this mesh won't be able to find the material during its loading!
		// I advise you not to use a recursive load (which load the full directory tree). 
		// Seriously, 'recursive loading' often leads to problems.
		Ogre::String lDirectoryToLoad = "../../media/mesh";
		bool lIsRecursive = false;
		lRgMgr.addResourceLocation(lDirectoryToLoad, "FileSystem", lNameOfResourceGroup, lIsRecursive);
		
		// The function 'initialiseResourceGroup' parses scripts if any in the locations.
		lRgMgr.initialiseResourceGroup(lNameOfResourceGroup);

		// Files that can be loaded are loaded.
		lRgMgr.loadResourceGroup(lNameOfResourceGroup);

		// Now the loaded Mesh is available from its ResourceGroup,
		// as well as from the Ogre::MeshManager. A shared pointer to
		// it can be accessed by : Ogre::MeshManager::getSingleton().getByName(name_of_the_mesh);

		// Now I can create Entities using that mesh.
		Ogre::String lNameOfTheMesh = "MonsterHead.mesh";
		int lNumberOfEntities = 5;
		for(int iter = 0; iter < lNumberOfEntities; ++iter)
		{
			Ogre::Entity* lEntity = lScene->createEntity(lNameOfTheMesh);
			// Now I attach it to a scenenode, so that it becomes present in the scene.
			Ogre::SceneNode* lNode = lRootSceneNode->createChildSceneNode();
			lNode->attachObject(lEntity);
			// I move the SceneNode so that it is visible to the camera.
			float lPositionOffset = float(1+ iter * 2) - (float(lNumberOfEntities));
			lPositionOffset = lPositionOffset * 20;
			lNode->translate(lPositionOffset, lPositionOffset, -200.0f);
			// The loaded mesh will be white. This is normal.
		}
	}

	// cleaning of windows events managed by Ogre::WindowEventUtilities::...
	// I call it after a 'pause in window updating', in order to maintain smoothness.
	// Explanation : if you clicked 2000 times when the windows was being created, there are 
	// at least 2000 messages created by the OS to listen to. This is made to clean them.
	lRoot->clearEventTimes();

	// I wait until the window is closed.
	// The "message pump" thing is something you will see in most GUI application.
	// It allow the binding of messages between the application and the OS.
	// These messages are most of the time : keystroke, mouse moved, ... or window closed.
	// If I don't do this, the message are never caught, and the window won't close.
	while(!lOgreInit.mWindow->isClosed())
	{
		// Drawings
		// the window update its content.
		// each viewport that is 'autoupdated' will be redrawn now,
		// in order given by its z-order.
		lWindow->update(false);

		// The drawn surface is then shown on the screen
		// (google "double buffering" if you want more details).
		// I always use vertical synchro.
		bool lVerticalSynchro = true;
		lWindow->swapBuffers(lVerticalSynchro);

		// This update some internal counters and listeners.
		// Each render surface (window/rtt/mrt) that is 'auto-updated' has got its 'update' function called.
		lRoot->renderOneFrame();

		Ogre::WindowEventUtilities::messagePump();
	}

	// Let's cleanup!
	{
		lWindow->removeAllViewports();
	}
	{
		lScene->destroyAllCameras();
		lScene->destroyAllManualObjects();
		lScene->destroyAllEntities();
		lRootSceneNode->removeAndDestroyAllChildren();
	}
	{
		Ogre::ResourceGroupManager& lRgMgr = Ogre::ResourceGroupManager::getSingleton();
		lRgMgr.destroyResourceGroup(lNameOfResourceGroup);
	}

	return;
}

int main()
{
	try
	{
		AnOgreApplication();
		std::cout<<"end of the program"<<std::endl;
	}catch(Ogre::Exception &e)
	{
		MWARNING("!!!!Ogre::Exception!!!!\n"<<e.what());
	}catch(std::exception &e)
	{
		MWARNING("!!!!std::exception!!!!\n"<<e.what());
	}
	return 0;
}


{CODE} 
Full program sources:
http://sourceforge.net/projects/so3dtools/files/Ogre3DWiki/05_BasicMeshLoading.7z/download
History: MadMarx Tutorial 5

Source of version: 9 (current)

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