/** Example 007 Collision

In this tutorial, I will show how to detect collisions with the Irrlicht Engine.
I will describe 3 methods: Automatic collision detection for moving through 3d
worlds with stair climbing and sliding, manual triangle picking, and manual
scene node picking.

To start, we take the program from tutorial 2, which loads and displays a quake
3 level. We will use the level to walk in it and to pick triangles from it. In
addition we'll place 3 animated models into it for scene node picking. The
following code starts up the engine and loads a quake 3 level. I will not
explain it, because it should already be known from tutorial 2.
*/
#include <irrlicht.h>
#include <iostream>

using namespace irr;

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

int main()
{
	// let user select driver type

	video::E_DRIVER_TYPE driverType;

	printf("Please select the driver you want for this example:\n"\
		" (a) Direct3D 9.0c\n (b) Direct3D 8.1\n (c) OpenGL 1.5\n"\
		" (d) Software Renderer\n (e) Burning's Software Renderer\n"\
		" (f) NullDevice\n (otherKey) exit\n\n");

	char i;
	std::cin >> i;

	switch(i)
	{
		case 'a': driverType = video::EDT_DIRECT3D9;break;
		case 'b': driverType = video::EDT_DIRECT3D8;break;
		case 'c': driverType = video::EDT_OPENGL;   break;
		case 'd': driverType = video::EDT_SOFTWARE; break;
		case 'e': driverType = video::EDT_BURNINGSVIDEO;break;
		case 'f': driverType = video::EDT_NULL;     break;
		default: return 0;
	}

	// create device

	IrrlichtDevice *device =
		createDevice(driverType, core::dimension2d<s32>(640, 480), 16, false);

	if (device == 0)
		return 1; // could not create selected driver.

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

	device->getFileSystem()->addZipFileArchive("../../media/map-20kdm2.pk3");

	scene::IAnimatedMesh* q3levelmesh = smgr->getMesh("20kdm2.bsp");
	scene::ISceneNode* q3node = 0;

	if (q3levelmesh)
		q3node = smgr->addOctTreeSceneNode(q3levelmesh->getMesh(0));

	/*
	So far so good, we've loaded the quake 3 level like in tutorial 2. Now,
	here comes something different: We create a triangle selector. A
	triangle selector is a class which can fetch the triangles from scene
	nodes for doing different things with them, for example collision
	detection. There are different triangle selectors, and all can be
	created with the ISceneManager. In this example, we create an
	OctTreeTriangleSelector, which optimizes the triangle output a little
	bit by reducing it like an octree. This is very useful for huge meshes
	like quake 3 levels. After we created the triangle selector, we attach
	it to the q3node. This is not necessary, but in this way, we do not
	need to care for the selector, for example dropping it after we do not
	need it anymore.
	*/

	scene::ITriangleSelector* selector = 0;

	if (q3node)
	{
		q3node->setPosition(core::vector3df(-1350,-130,-1400));

		selector = smgr->createOctTreeTriangleSelector(
				q3levelmesh->getMesh(0), q3node, 128);
		q3node->setTriangleSelector(selector);
	}


	/*
	We add a first person shooter camera to the scene for being able to
	move in the quake 3 level like in tutorial 2. But this, time, we add a
	special animator to the camera: A Collision Response animator. This
	thing modifies the scene node to which it is attached to in that way,
	that it may no more move through walls and is affected by gravity. The
	only thing we have to tell the animator is how the world looks like,
	how big the scene node is, how gravity and so on. After the collision
	response animator is attached to the camera, we do not have to do
	anything more for collision detection, anything is done automaticly,
	all other collision detection code below is for picking. And please
	note another cool feature: The collsion response animator can be
	attached also to all other scene nodes, not only to cameras. And it can
	be mixed with other scene node animators. In this way, collision
	detection and response in the Irrlicht engine is really, really easy.

	Now we'll take a closer look on the parameters of
	createCollisionResponseAnimator(). The first parameter is the
	TriangleSelector, which specifies how the world, against collision
	detection is done looks like. The second parameter is the scene node,
	which is the object, which is affected by collision detection, in our
	case it is the camera. The third defines how big the object is, it is
	the radius of an ellipsoid. Try it out and change the radius to smaller
	values, the camera will be able to move closer to walls after this. The
	next parameter is the direction and speed of gravity. You could set it
	to (0,0,0) to disable gravity. And the last value is just a
	translation: Without this, the ellipsoid with which collision detection
	is done would be around the camera, and the camera would be in the
	middle of the ellipsoid. But as human beings, we are used to have our
	eyes on top of the body, with which we collide with our world, not in
	the middle of it. So we place the scene node 50 units over the center
	of the ellipsoid with this parameter. And that's it, collision
	detection works now.
	*/

	scene::ICameraSceneNode* camera =
		smgr->addCameraSceneNodeFPS(0, 100.0f, 300.0f, -1, 0, 0, true);
	camera->setPosition(core::vector3df(-100,50,-150));

	if (selector)
	{
		scene::ISceneNodeAnimator* anim = smgr->createCollisionResponseAnimator(
			selector, camera, core::vector3df(30,50,30),
			core::vector3df(0,-3,0),
			core::vector3df(0,50,0));
		camera->addAnimator(anim);
		anim->drop();
	}

	/*
	Because collision detection is no big deal in irrlicht, I'll describe how to
	do two different types of picking in the next section. But before this,
	I'll prepare the scene a little. I need three animated characters which we
	could pick later, a dynamic light for lighting them,
	a billboard for drawing where we found an intersection,	and, yes, I need to
	get rid of this mouse cursor. :)
	*/

	// disable mouse cursor

	device->getCursorControl()->setVisible(false);

	// add billboard

	scene::IBillboardSceneNode * bill = smgr->addBillboardSceneNode();
	bill->setMaterialType(video::EMT_TRANSPARENT_ADD_COLOR );
	bill->setMaterialTexture(0, driver->getTexture("../../media/particle.bmp"));
	bill->setMaterialFlag(video::EMF_LIGHTING, false);
	bill->setMaterialFlag(video::EMF_ZBUFFER, false);
	bill->setSize(core::dimension2d<f32>(20.0f, 20.0f));

	// add 3 animated faeries.

	video::SMaterial material;
	material.setTexture(0, driver->getTexture("../../media/faerie2.bmp"));
	material.Lighting = true;

	scene::IAnimatedMeshSceneNode* node = 0;
	scene::IAnimatedMesh* faerie = smgr->getMesh("../../media/faerie.md2");

	if (faerie)
	{
		node = smgr->addAnimatedMeshSceneNode(faerie);
		node->setPosition(core::vector3df(-70,0,-90));
		node->setMD2Animation(scene::EMAT_RUN);
		node->getMaterial(0) = material;

		node = smgr->addAnimatedMeshSceneNode(faerie);
		node->setPosition(core::vector3df(-70,0,-30));
		node->setMD2Animation(scene::EMAT_SALUTE);
		node->getMaterial(0) = material;

		node = smgr->addAnimatedMeshSceneNode(faerie);
		node->setPosition(core::vector3df(-70,0,-60));
		node->setMD2Animation(scene::EMAT_JUMP);
		node->getMaterial(0) = material;
	}

	material.setTexture(0, 0);
	material.Lighting = false;

	// Add a light

	smgr->addLightSceneNode(0, core::vector3df(-60,100,400),
		video::SColorf(1.0f,1.0f,1.0f,1.0f),
		600.0f);


	/*
	For not making it to complicated, I'm doing picking inside the drawing
	loop. We take two pointers for storing the current and the last
	selected scene node and start the loop.
	*/


	scene::ISceneNode* selectedSceneNode = 0;
	scene::ISceneNode* lastSelectedSceneNode = 0;


	int lastFPS = -1;

	while(device->run())
	if (device->isWindowActive())
	{
		driver->beginScene(true, true, 0);

		smgr->drawAll();

		/*
		After we've drawn the whole scene with smgr->drawAll(), we'll
		do the first picking: We want to know which triangle of the
		world we are looking at. In addition, we want the exact point
		of the quake 3 level we are looking at. For this, we create a
		3d line starting at the position of the camera and going
		through the lookAt-target of it. Then we ask the collision
		manager if this line collides with a triangle of the world
		stored in the triangle selector. If yes, we draw the 3d
		triangle and set the position of the billboard to the
		intersection point.
		*/

		core::line3d<f32> line;
		line.start = camera->getPosition();
		line.end = line.start + (camera->getTarget() - line.start).normalize() * 1000.0f;

		core::vector3df intersection;
		core::triangle3df tri;

		if (smgr->getSceneCollisionManager()->getCollisionPoint(
			line, selector, intersection, tri))
		{
			bill->setPosition(intersection);

			driver->setTransform(video::ETS_WORLD, core::matrix4());
			driver->setMaterial(material);
			driver->draw3DTriangle(tri, video::SColor(0,255,0,0));
		}


		/*
		Another type of picking supported by the Irrlicht Engine is
		scene node picking based on bounding boxes. Every scene node has
		got a bounding box, and because of that, it's very fast for
		example to get the scene node which the camera looks at. Again,
		we ask the collision manager for this, and if we've got a scene
		node, we highlight it by disabling Lighting in its material, if
		it is not the billboard or the quake 3 level.
		*/

		selectedSceneNode =
			smgr->getSceneCollisionManager()->getSceneNodeFromCameraBB(camera);

		if (lastSelectedSceneNode)
			lastSelectedSceneNode->setMaterialFlag(video::EMF_LIGHTING, true);

		if (selectedSceneNode == q3node || selectedSceneNode == bill)
			selectedSceneNode = 0;

		if (selectedSceneNode)
			selectedSceneNode->setMaterialFlag(video::EMF_LIGHTING, false);

		lastSelectedSceneNode = selectedSceneNode;


		/*
		That's it, we just have to finish drawing.
		*/

		driver->endScene();

		int fps = driver->getFPS();

		if (lastFPS != fps)
		{
			core::stringw str = L"Collision detection example - Irrlicht Engine [";
			str += driver->getName();
			str += "] FPS:";
			str += fps;

			device->setWindowCaption(str.c_str());
			lastFPS = fps;
		}
	}

	selector->drop();
	device->drop();

	return 0;
}

/*
**/
