History: MadMarx Tutorial 3

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            !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, I present one way to create a 3D object from scratch.
This is useful if you intend to load your own 3D data format without difficulties (shapefile, ...),
or to create some procedural stuff.

!!A Simplistic presentation of 3D
A simplistic presentation of some realtime 3D basics.
In 3D you need most of the time :
a vertex table Vt + an index table Idt + a kind of primitive P + an associated ((-Material|material)) M.
Let's say P is "triangle" (most common), then Idt will contain
a list of index taken from Vt, where each group of 3 index means a triangle.
so (Idt[0], Idt[1],Idt[2]) is the first triangle, (Idt[3],Idt[4],Idt[5]) is the second, etc...

When times come to render this whole thing,
it will be multiplied by 2 matrix.
1/ a matrix representing transformation(position/orientation/scale) of the thing relative to the ((-Camera|camera)).
2/ a perspective matrix, corresponding to the parameters of the viewing ((-Camera|camera)).
Ogre will prepare both matrix for you. But you can also provide them if you want.
This calculation can be modified in vertex shaders.

Once it has been projected, the graphic card uses the buffers (mainly colour and depth)
, vertex attributes and ((-Material|material)) informations (from M) to draw things.
vertex attributes are used to '((-Light|light))', 'colourize', and '((-Texture|texture))' the meshes.
This calculation can be partially modified in pixel shaders.
This was a very simplistic presentation of 3D rendering ^^.

!!New Include

{CODE(wrap="1",colors="c++")} 
¤#include "OGRE/OgreManualObject.h"
{CODE} 
!!After viewport creation
Here, I create a 3D element, by using the interface of ((ManualObject)).
((ManualObject)) is very close to the opengl old simple way to specify geometry.
There are other interfaces (Hardwarebuffers), you can check the ogremanual fo them and wiki.
For each vertex I will provide positions and attributes (normal, vertex color, ((-Texture|texture)) coordinates...).
Then for each primitive (given its type : triangle, line, line strip etc...),
I give the corresponding group of vertex index.

{CODE(wrap="1",colors="c++")} 
¤		Ogre::ManualObject* lManualObject = NULL;
		{
{CODE} 
The manualObject creation requires a name.

{CODE(wrap="1",colors="c++")} 
¤			Ogre::String lManualObjectName = "SomeQuad";
			lManualObject = lScene->createManualObject(lManualObjectName);
{CODE} 
Always tell if you want to update the 3D (vertex/index) later or not.

{CODE(wrap="1",colors="c++")} 
¤			bool lDoIWantToUpdateItLater = false;
			lManualObject->setDynamic(lDoIWantToUpdateItLater);
{CODE} 
BaseWhiteNoLighting is the name of a ((-Material|material)) that already exist inside Ogre.
Ogre::RenderOperation::OT_TRIANGLE_LIST is a kind of primitive.

{CODE(wrap="1",colors="c++")} 
¤			lManualObject->begin("BaseWhiteNoLighting", Ogre::RenderOperation::OT_TRIANGLE_LIST);
			{
{CODE} 
a vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->position(0.0,0.0,0.0);
{CODE} 
its attributes. Here I only set 1 colour.

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->colour(1.0,0.0,0.0); 
{CODE} 
a vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->position(0.0,1.0,0.0);
				lManualObject->colour(0.0,1.0,0.0);
{CODE} 
a vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->position(1.0,1.0,0.0);
				lManualObject->colour(0.0,0.0,1.0);
{CODE} 
a vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->position(1.0,0.0,0.0);
				lManualObject->colour(1.0,1.0,1.0);
{CODE} 
a group of 3 vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->triangle(3,2,1);
{CODE} 
a group of 3 vertex

{CODE(wrap="1",colors="c++")} 
¤				lManualObject->triangle(1,0,3);
{CODE} 
I could have used quad(3,2,1,0) instead of 2 triangles.

{CODE(wrap="1",colors="c++")} 
¤			}
			lManualObject->end();
{CODE} 
Here I have finished my ((ManualObject)) construction.
It is possible to add more begin()-end() thing, in order to use
different rendering operation types, or different materials in 1 ((ManualObject)).

{CODE(wrap="1",colors="c++")} 
¤		}
{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(lManualObject);
{CODE} 
I move the ((-SceneNode|SceneNode)) so that it is visible to the ((-Camera|camera)).

{CODE(wrap="1",colors="c++")} 
¤		lNode->translate(0.0,0.0,-10.0);
{CODE} 

! main.cpp 
{CODE(wrap="1",colors="c++")} 
//
// Copyright (c) 2007-2010, 'Madmarx' from the ogre3D forums (ogre3D.org).
// All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of its author nor the names of its contributors
//       may be used to endorse or promote products derived from this software
//       without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ------------------------------------------------------------------------------//
// ------------------------------------------------------------------------------//

// In this program, I present one way to create a 3D object from scratch.
// This is useful if you intend to load your own 3D data format without difficulties (shapefile, ...),
// or to create some procedural stuff.

// 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"

//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);

	// A simplistic presentation of some realtime 3D basics.
	// In 3D you need most of the time : 
	// a vertex table Vt + an index table Idt + a kind of primitive P + an associated material M.
	// Let's say P is "triangle" (most common), then Idt will contain
	// a list of index taken from Vt, where each group of 3 index means a triangle.
	// so (Idt[0], Idt[1],Idt[2]) is the first triangle, (Idt[3],Idt[4],Idt[5]) is the second, etc...
	//
	// When times come to render this whole thing, 
	// it will be multiplied by 2 matrix.
	// 1/ a matrix representing transformation(position/orientation/scale) of the thing relative to the camera.
	// 2/ a perspective matrix, corresponding to the parameters of the viewing camera.
	// Ogre will prepare both matrix for you. But you can also provide them if you want.
	// This calculation can be modified in vertex shaders.
	//
	// Once it has been projected, the graphic card uses the buffers (mainly colour and depth)
	// , vertex attributes and material informations (from M) to draw things.
	// vertex attributes are used to 'light', 'colourize', and 'texture' the meshes.
	// This calculation can be partially modified in pixel shaders.
	// This was a very simplistic presentation of 3D rendering ^^.
	{
		// Here, I create a 3D element, by using the interface of ManualObject.
		// ManualObject is very close to the opengl old simple way to specify geometry.
		// There are other interfaces (Hardwarebuffers), you can check the ogremanual fo them and wiki.
		// For each vertex I will provide positions and attributes (normal, vertex color, texture coordinates...).
		// Then for each primitive (given its type : triangle, line, line strip etc...), 
		// I give the corresponding group of vertex index.
		Ogre::ManualObject* lManualObject = NULL;
		{
			// The manualObject creation requires a name.
			Ogre::String lManualObjectName = "SomeQuad";
			lManualObject = lScene->createManualObject(lManualObjectName);

			// Always tell if you want to update the 3D (vertex/index) later or not.
			bool lDoIWantToUpdateItLater = false;
			lManualObject->setDynamic(lDoIWantToUpdateItLater);

			// BaseWhiteNoLighting is the name of a material that already exist inside Ogre.
			// Ogre::RenderOperation::OT_TRIANGLE_LIST is a kind of primitive.
			lManualObject->begin("BaseWhiteNoLighting", Ogre::RenderOperation::OT_TRIANGLE_LIST);
			{
				// a vertex
				lManualObject->position(0.0,0.0,0.0);
				// its attributes. Here I only set 1 colour.
				lManualObject->colour(1.0,0.0,0.0); 

				// a vertex
				lManualObject->position(0.0,1.0,0.0);
				lManualObject->colour(0.0,1.0,0.0);

				// a vertex
				lManualObject->position(1.0,1.0,0.0);
				lManualObject->colour(0.0,0.0,1.0);

				// a vertex
				lManualObject->position(1.0,0.0,0.0);
				lManualObject->colour(1.0,1.0,1.0);

				// a group of 3 vertex
				lManualObject->triangle(3,2,1);

				// a group of 3 vertex
				lManualObject->triangle(1,0,3);
				// I could have used quad(3,2,1,0) instead of 2 triangles.
			}
			lManualObject->end();
			// Here I have finished my ManualObject construction.
			// It is possible to add more begin()-end() thing, in order to use 
			// different rendering operation types, or different materials in 1 ManualObject.
		}
		// Now I attach it to a scenenode, so that it becomes present in the scene.
		Ogre::SceneNode* lNode = lRootSceneNode->createChildSceneNode();
		lNode->attachObject(lManualObject);
		// I move the SceneNode so that it is visible to the camera.
		lNode->translate(0.0,0.0,-10.0);
	}

	// 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();
	}
	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}