MadMarx Tutorial 10         Input Using OIS

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!

Tutorial Description

Since input is quite useful for some tests, I will show
a very basic usage of the OIS library. Bear in mind that
I could have used another input system or library
(ex: CImg, camera tracking, conio, ...).

In this program I create 5 entities, and then I will control in
realtime the camera with the mouse, and the keyboard (T,G,F,H).
When the left button of the mouse is pushed, the colour of the
viewport changes randomly.
The escape button of the keyboard allows to quit.

The controls are made in realtime. To do that, I use Ogre's timer
to determinate how much time as flown between 2 frames :
speed * elapsed time between 2 frames = deplacement to do between 2 frames.

I also print some informations about performances.
Please note that you can also find all of this in the official Ogre3D tutorials.

After window creation

I prefer to be able to access my variables directly.

¤	Ogre::Root* lRoot = lOgreInit.mRoot.get();
	Ogre::RenderWindow* lWindow = lOgreInit.mWindow;

Here I create the necessary objects of OIS to manage Keyboard and Mouse.

¤	OIS::InputManager* lInputManager = NULL;
	OIS::Mouse* lMouse = NULL;
	OIS::Keyboard* lKeyboard = NULL;
	{

The input/output system needs an handle to a window as input, in a string format.
1/ we need to get the "windows-API" handle

¤		size_t windowHandle = 0;
		lWindow->getCustomAttribute("WINDOW", &windowHandle);

2/ convert it into a string

¤		std::string windowsHandleAsString="";
		{
			std::ostringstream windowHndStr;
			windowHndStr << windowHandle;
			windowsHandleAsString = windowHndStr.str();
		}

3/ we translate it into a format accepted by OIS (the input library).

¤		OIS::ParamList lSpecialParameters;
		lSpecialParameters.insert(std::make_pair(std::string("WINDOW"), windowsHandleAsString));

4/ we create the input/output system itself.

¤		lInputManager = OIS::InputManager::createInputSystem( lSpecialParameters );

the events can be stored or not in a buffer

¤		bool lBufferedKeys = false;
		bool lBufferedMouse = false;

creation of the keyboard-representing object

¤		lKeyboard = static_cast<OIS::Keyboard*>(lInputManager->createInputObject(OIS::OISKeyboard, lBufferedKeys));

creation of the mouse-representing object

¤		lMouse = static_cast<OIS::Mouse*>(lInputManager->createInputObject( OIS::OISMouse, lBufferedMouse));

then must tell the mouse how much it is allowed to move.

¤		const OIS::MouseState &infoSouris = lMouse->getMouseState();
		infoSouris.width = lWindow->getWidth();
		infoSouris.height = lWindow->getHeight();
	}

Before the while() loop

The root has an access to Ogre3D's internal timer.
This timer can be controlled (for example, if you want to synchronise
some shaders between 5 computers), and accessed for time informations.
Here I reset the timer.

¤	Ogre::Timer* lOgreTimer = lRoot->getTimer();
	lOgreTimer->reset();

I name my variable with something that indicates milliseconds or seconds.
Here the _Ms means 'milliseconds',and '_s' means 'seconds'.

¤	unsigned long lLastTime_Ms = lOgreTimer->getMilliseconds();
	unsigned long lDeltaTime_Ms = 0;
	float lDeltaTime_s = 0.0f;

The while() loop

¤	while(!lOgreInit.mWindow->isClosed())
	{

For the window drawing, you will increase performances if you :
0/ do some cpu calculations (ex: update sound).
1/ clear the window buffer (Ogre::Viewport::clear)
2/ do some cpu calculations (ex: particles)
3/ draw the scene without swapping buffers (render() / update())
4/ do some cpu calculations (ex : physics + logics)
5/ swap the buffers(). (swapBuffers())
6/ go back to 0/
Ogre allows to do that automatically if you use a framelistener,
like in the official ogre tutorials.

In this tutorial series, I don't want to bother you with that,
but you might keep that in mind when you design your final application.
Also it's better to launch sound first, because sound is slower than light.

I evaluate the current time and the time elapsed since last frame
I also prepare the next iteration.

¤		{
			unsigned long lCurrentTime_Ms = lOgreTimer->getMilliseconds();
			lDeltaTime_Ms = lCurrentTime_Ms - lLastTime_Ms;
			if(lDeltaTime_Ms == 0)
			{
				continue;
			}
			lLastTime_Ms = lCurrentTime_Ms;
			lDeltaTime_s = 0.001f * float(lDeltaTime_Ms);
		}

I capture the keyboard settings.
Then I update the scene according to these informations.

¤		lKeyboard->capture();

The current time is used in the calculation : this is 'real time'.
The camera move with the same speed on any computer.
I put a coefficient 200.0 because the scene is big.
I test the keys TGFH for moving.

¤		{
			float lCoeff = 200.0f * lDeltaTime_s;
			Ogre::Vector3 lTranslation(Ogre::Vector3::ZERO);
			if(lKeyboard->isKeyDown(OIS::KC_T))
			{
				lTranslation.z -= lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_G))
			{
				lTranslation.z += lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_F))
			{
				lTranslation.x -= lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_H))
			{
				lTranslation.x += lCoeff;
			}
			if(lTranslation != Ogre::Vector3::ZERO)
			{
				lCameraNode->translate(lTranslation, Ogre::Node::TS_LOCAL);
			}
			if(lKeyboard->isKeyDown(OIS::KC_ESCAPE))
			{
				break;
			}
		}

same for the mouse.

¤		{
			lMouse->capture();
			const OIS::MouseState& lMouseState = lMouse->getMouseState();
			if(lMouseState.buttonDown(OIS::MB_Left))
			{

I change the colour of the background...

¤				float red	= Ogre::Math::RangeRandom(0.1f,0.9f);
				float green = Ogre::Math::RangeRandom(0.1f,0.9f);
				float blue	= Ogre::Math::RangeRandom(0.1f,0.9f);
				vp->setBackgroundColour(Ogre::ColourValue( red, green, blue));
			}
			float lMouseX = float(lMouseState.X.rel) / float(lWindow->getWidth());
			float lMouseY = float(lMouseState.Y.rel) / float(lWindow->getHeight());
			float lRotCoeff = -5.0f;
			Ogre::Radian lAngleX(lMouseX * lRotCoeff);
			Ogre::Radian lAngleY(lMouseY * lRotCoeff);

If the 'player' don't make loopings, 'yaw in world' + 'pitch in local' is often enough for a camera controler.

¤			lCameraNode->yaw(lAngleX, Ogre::Node::TS_WORLD);
			lCameraNode->pitch(lAngleY, Ogre::Node::TS_LOCAL);
		}

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);

I print some statistics (more are available in Ogre3D)
With VSync enabled, that should be close to 59,9fps.

¤		const Ogre::RenderTarget::FrameStats& lStats = lWindow->getStatistics();
		std::cout<<"FPS: "<<lStats.lastFPS<<"; AvgFPS : "<<lStats.avgFPS;
		std::cout<<"; batchcount :"<<lStats.batchCount<<std::endl;

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();
	}

main.cpp

// Since input is quite useful for some tests, I will show
// a very basic usage of the OIS library. Bear in mind that 
// I could have used another input system or library 
// (ex: CImg, camera tracking, conio, ...).
//
// In this program I create 5 entities, and then I will control in
// realtime the camera with the mouse, and the keyboard (T,G,F,H).
// When the left button of the mouse is pushed, the colour of the 
// viewport changes randomly.
// The escape button of the keyboard allows to quit.
// 
// The controls are made in realtime. To do that, I use Ogre's timer
// to determinate how much time as flown between 2 frames :
// speed * elapsed time between 2 frames = deplacement to do between 2 frames.
//
// I also print some informations about performances.
// Please note that you can also find all of this in the official Ogre3D tutorials.

// 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"

#include "OIS\Ois.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;

	// Here I create the necessary objects of OIS to manage Keyboard and Mouse.
	OIS::InputManager* lInputManager = NULL;
	OIS::Mouse* lMouse = NULL;
	OIS::Keyboard* lKeyboard = NULL;
	{
		// The input/output system needs an handle to a window as input, in a string format.
		// 1/ we need to get the "windows-API" handle
		size_t windowHandle = 0;
		lWindow->getCustomAttribute("WINDOW", &windowHandle);

		// 2/ convert it into a string
		std::string windowsHandleAsString="";
		{
			std::ostringstream windowHndStr;
			windowHndStr << windowHandle;
			windowsHandleAsString = windowHndStr.str();
		}

		// 3/ we translate it into a format accepted by OIS (the input library).
		OIS::ParamList lSpecialParameters;
		lSpecialParameters.insert(std::make_pair(std::string("WINDOW"), windowsHandleAsString));

		// 4/ we create the input/output system itself.
		lInputManager = OIS::InputManager::createInputSystem( lSpecialParameters );

		// the events can be stored or not in a buffer
		bool lBufferedKeys = false;
		bool lBufferedMouse = false;

		// creation of the keyboard-representing object
		lKeyboard = static_cast<OIS::Keyboard*>(lInputManager->createInputObject(OIS::OISKeyboard, lBufferedKeys));

		// creation of the mouse-representing object
		lMouse = static_cast<OIS::Mouse*>(lInputManager->createInputObject( OIS::OISMouse, lBufferedMouse));

		// then must tell the mouse how much it is allowed to move.
		const OIS::MouseState &infoSouris = lMouse->getMouseState();
		infoSouris.width = lWindow->getWidth();
		infoSouris.height = lWindow->getHeight();
	}

	// 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();

	// The root has an access to Ogre3D's internal timer.
	// This timer can be controlled (for example, if you want to synchronise
	// some shaders between 5 computers), and accessed for time informations.
	// Here I reset the timer.
	Ogre::Timer* lOgreTimer = lRoot->getTimer();
	lOgreTimer->reset();
	
	// I name my variable with something that indicates milliseconds or seconds.
	// Here the _Ms means 'milliseconds',and '_s' means 'seconds'.
	unsigned long lLastTime_Ms = lOgreTimer->getMilliseconds();
	unsigned long lDeltaTime_Ms = 0;
	float lDeltaTime_s = 0.0f;
	// 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())
	{
		// For the window drawing, you will increase performances if you : 
		// 0/ do some cpu calculations (ex: update sound).
		// 1/ clear the window buffer (Ogre::Viewport::clear)
		// 2/ do some cpu calculations (ex: particles)
		// 3/ draw the scene without swapping buffers (render() / update())
		// 4/ do some cpu calculations (ex : physics + logics)
		// 5/ swap the buffers(). (swapBuffers())
		// 6/ go back to 0/
		// Ogre allows to do that automatically if you use a framelistener,
		// like in the official ogre tutorials.
		// 
		// In this tutorial series, I don't want to bother you with that,
		// but you might keep that in mind when you design your final application.
		// Also it's better to launch sound first, because sound is slower than light.

		// I evaluate the current time and the time elapsed since last frame
		// I also prepare the next iteration.
		{
			unsigned long lCurrentTime_Ms = lOgreTimer->getMilliseconds();
			lDeltaTime_Ms = lCurrentTime_Ms - lLastTime_Ms;
			if(lDeltaTime_Ms == 0)
			{
				continue;
			}
			lLastTime_Ms = lCurrentTime_Ms;
			lDeltaTime_s = 0.001f * float(lDeltaTime_Ms);
		}

		// I capture the keyboard settings.
		// Then I update the scene according to these informations.
		lKeyboard->capture();

		// The current time is used in the calculation : this is 'real time'. 
		// The camera move with the same speed on any computer.
		// I put a coefficient 200.0 because the scene is big.
		// I test the keys TGFH for moving.
		{
			float lCoeff = 200.0f * lDeltaTime_s;
			Ogre::Vector3 lTranslation(Ogre::Vector3::ZERO);
			if(lKeyboard->isKeyDown(OIS::KC_T))
			{
				lTranslation.z -= lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_G))
			{
				lTranslation.z += lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_F))
			{
				lTranslation.x -= lCoeff;
			}
			if(lKeyboard->isKeyDown(OIS::KC_H))
			{
				lTranslation.x += lCoeff;
			}
			if(lTranslation != Ogre::Vector3::ZERO)
			{
				lCameraNode->translate(lTranslation, Ogre::Node::TS_LOCAL);
			}
			if(lKeyboard->isKeyDown(OIS::KC_ESCAPE))
			{
				break;
			}
		}

		// same for the mouse.
		{
			lMouse->capture();
			const OIS::MouseState& lMouseState = lMouse->getMouseState();
			if(lMouseState.buttonDown(OIS::MB_Left))
			{
				// I change the colour of the background...
				float red	= Ogre::Math::RangeRandom(0.1f,0.9f);
				float green = Ogre::Math::RangeRandom(0.1f,0.9f);
				float blue	= Ogre::Math::RangeRandom(0.1f,0.9f);
				vp->setBackgroundColour(Ogre::ColourValue( red, green, blue));
			}
			float lMouseX = float(lMouseState.X.rel) / float(lWindow->getWidth());
			float lMouseY = float(lMouseState.Y.rel) / float(lWindow->getHeight());
			float lRotCoeff = -5.0f;
			Ogre::Radian lAngleX(lMouseX * lRotCoeff);
			Ogre::Radian lAngleY(lMouseY * lRotCoeff);
			// If the 'player' don't make loopings, 'yaw in world' + 'pitch in local' is often enough for a camera controler.
			lCameraNode->yaw(lAngleX, Ogre::Node::TS_WORLD);
			lCameraNode->pitch(lAngleY, Ogre::Node::TS_LOCAL);
		}

		// 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);

		// I print some statistics (more are available in Ogre3D)
		// With VSync enabled, that should be close to 59,9fps.
		const Ogre::RenderTarget::FrameStats& lStats = lWindow->getStatistics();
		std::cout<<"FPS: "<<lStats.lastFPS<<"; AvgFPS : "<<lStats.avgFPS;
		std::cout<<"; batchcount :"<<lStats.batchCount<<std::endl;

		// 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!
	{
		lInputManager->destroyInputObject(lKeyboard);
		lKeyboard = NULL;
		lInputManager->destroyInputObject(lMouse);
		lMouse = NULL;
		OIS::InputManager::destroyInputSystem(lInputManager);
		lInputManager = NULL;
	}
	{
		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;
}

Full program sources:
http://sourceforge.net/projects/so3dtools/files/Ogre3DWiki/10_RealTime_Input.7z/download

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