irrlicht/examples/18.SplitScreen/main.cpp

/** Example 018 Splitscreen

A tutorial by Max Winkel.

In this tutorial we'll learn how to use splitscreen (e.g. for racing-games)
with Irrlicht. We'll create a viewport divided
into 4 parts, with 3 fixed cameras and one user-controlled.

Ok, let's start with the headers (I think there's
nothing to say about it)
*/

#include <irrlicht.h>
#include "driverChoice.h"

#ifdef _MSC_VER
#pragma comment(lib, "Irrlicht.lib")
#endif

//Namespaces for the engine
using namespace irr;
using namespace core;
using namespace video;
using namespace scene;

/*
Now we'll define the resolution in a constant for use in
initializing the device and setting up the viewport. In addition
we set up a global variable saying splitscreen is active or not.
*/
//Resolution
const int ResX=800;
const int ResY=600;
const bool fullScreen=false;

//Use SplitScreen?
bool SplitScreen=true;

/*
Now we need four pointers to our cameras which are created later:
*/
//cameras
ICameraSceneNode *camera[4]={0,0,0,0};
/*
In our event-receiver we switch the SplitScreen-variable,
whenever the user press the S-key. All other events are sent
to the FPS camera.
*/

class MyEventReceiver : public IEventReceiver
{
	public:
		virtual bool OnEvent(const SEvent& event)
		{
			//Key S enables/disables SplitScreen
			if (event.EventType == irr::EET_KEY_INPUT_EVENT &&
				event.KeyInput.Key == KEY_KEY_S && event.KeyInput.PressedDown)
			{
				SplitScreen = !SplitScreen;
				return true;
			}
			//Send all other events to camera4
			if (camera[3])
				return camera[3]->OnEvent(event);
			return false;
		}
};

/*
Ok, now the main-function:
First, we initialize the device, get the SourceManager and
VideoDriver, load an animated mesh from .md2 and a map from
.pk3. Because that's old stuff, I won't explain every step.
Just take care of the maps position.
*/
int main()
{
	// ask user for driver
	video::E_DRIVER_TYPE driverType=driverChoiceConsole();
	if (driverType==video::EDT_COUNT)
		return 1;

	//Instance of the EventReceiver
	MyEventReceiver receiver;

	//Initialise the engine
	IrrlichtDevice *device = createDevice(driverType,
			dimension2du(ResX,ResY), 32, fullScreen,
			false, false, &receiver);
	if (!device)
		return 1;

	ISceneManager *smgr = device->getSceneManager();
	IVideoDriver *driver = device->getVideoDriver();

	//Load model
	IAnimatedMesh *model = smgr->getMesh("../../media/sydney.md2");
	if (!model)
		return 1;
	IAnimatedMeshSceneNode *model_node = smgr->addAnimatedMeshSceneNode(model);
	//Load texture
	if (model_node)
	{
		ITexture *texture = driver->getTexture("../../media/sydney.bmp");
		model_node->setMaterialTexture(0,texture);
		model_node->setMD2Animation(scene::EMAT_RUN);
		//Disable lighting (we've got no light)
		model_node->setMaterialFlag(EMF_LIGHTING,false);
	}

	//Load map
	device->getFileSystem()->addFileArchive("../../media/map-20kdm2.pk3");
	IAnimatedMesh *map = smgr->getMesh("20kdm2.bsp");
	if (map)
	{
		ISceneNode *map_node = smgr->addOctreeSceneNode(map->getMesh(0));
		//Set position
		map_node->setPosition(vector3df(-850,-220,-850));
	}

/*
Now we create our four cameras. One is looking at the model
from the front, one from the top and one from the side. In
addition there's a FPS-camera which can be controlled by the
user.
*/
	// Create 3 fixed and one user-controlled cameras
	//Front
	camera[0] = smgr->addCameraSceneNode(0, vector3df(50,0,0), vector3df(0,0,0));
	//Top
	camera[1] = smgr->addCameraSceneNode(0, vector3df(0,50,0), vector3df(0,0,0));
	//Left
	camera[2] = smgr->addCameraSceneNode(0, vector3df(0,0,50), vector3df(0,0,0));
	//User-controlled
	camera[3] = smgr->addCameraSceneNodeFPS();
	// don't start at sydney's position
	if (camera[3])
		camera[3]->setPosition(core::vector3df(-50,0,-50));

/*
Create a variable for counting the fps and hide the mouse:
*/
	//Hide mouse
	device->getCursorControl()->setVisible(false);
	//We want to count the fps
	int lastFPS = -1;

/*
There wasn't much new stuff - till now!
Only by defining four cameras, the game won't be splitscreen.
To do this you need several steps:
  - Set the viewport to the whole screen
  - Begin a new scene (Clear screen)

  - The following 3 steps are repeated for every viewport in the splitscreen
    - Set the viewport to the area you wish
    - Activate the camera which should be "linked" with the viewport
    - Render all objects

  - If you have a GUI:
    - Set the viewport the whole screen
    - Display the GUI
  - End scene

Sounds a little complicated, but you'll see it isn't:
*/

	while(device->run())
	{
		//Set the viewpoint to the whole screen and begin scene
		driver->setViewPort(rect<s32>(0,0,ResX,ResY));
		driver->beginScene(true,true,SColor(255,100,100,100));
		//If SplitScreen is used
		if (SplitScreen)
		{
			//Activate camera1
			smgr->setActiveCamera(camera[0]);
			//Set viewpoint to the first quarter (left top)
			driver->setViewPort(rect<s32>(0,0,ResX/2,ResY/2));
			//Draw scene
			smgr->drawAll();
			//Activate camera2
			smgr->setActiveCamera(camera[1]);
			//Set viewpoint to the second quarter (right top)
			driver->setViewPort(rect<s32>(ResX/2,0,ResX,ResY/2));
			//Draw scene
			smgr->drawAll();
			//Activate camera3
			smgr->setActiveCamera(camera[2]);
			//Set viewpoint to the third quarter (left bottom)
			driver->setViewPort(rect<s32>(0,ResY/2,ResX/2,ResY));
			//Draw scene
			smgr->drawAll();
			//Set viewport the last quarter (right bottom)
			driver->setViewPort(rect<s32>(ResX/2,ResY/2,ResX,ResY));
		}
		//Activate camera4
		smgr->setActiveCamera(camera[3]);
		//Draw scene
		smgr->drawAll();
		driver->endScene();

		/*
		As you can probably see, the image is rendered for every
		viewport separately. That means, that you'll loose much performance.
		Ok, if you're asking "How do I have to set the viewport
		to get this or that screen?", don't panic. It's really
		easy: In the rect-function you define 4 coordinates:
		- X-coordinate of the corner left top
		- Y-coordinate of the corner left top
		- X-coordinate of the corner right bottom
		- Y-coordinate of the corner right bottom

		That means, if you want to split the screen into 2 viewports
		you would give the following coordinates:
		- 1st viewport: 0,0,ResX/2,ResY
		- 2nd viewport: ResX/2,0,ResX,ResY

		If you didn't fully understand, just play around with the example
		to check out what happens.

		Now we just view the current fps and shut down the engine,
		when the user wants to:
		*/
		//Get and show fps
		if (driver->getFPS() != lastFPS)
		{
			lastFPS = driver->getFPS();
			core::stringw tmp = L"Irrlicht SplitScreen-Example (FPS: ";
			tmp += lastFPS;
			tmp += ")";
			device->setWindowCaption(tmp.c_str());
		}
	}
	//Delete device
	device->drop();
	return 0;
}
/*
That's it! Just compile and play around with the program.
Note: With the S-Key you can switch between using splitscreen
and not.
**/