main.cpp
/////////////

#include <iostream>

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

using namespace irr;

int main()
{

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


    device->setWindowCaption(L"Custom Scene Node - Irrlicht Engine Demo");

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

    scene::ICameraSceneNode* camera =
        smgr->addCameraSceneNodeFPS(0,100.0f,1200.0f);
    scene::ITerrainSceneNode* terrain = smgr->addTerrainSceneNode(
                                            "../../media/terrain-heightmap.bmp");
    terrain->setScale(core::vector3df(10, 4.4f, 10));
    CGrassNode * node= new CGrassNode(terrain,smgr,0);


    terrain->setMaterialFlag(video::EMF_LIGHTING, false);

    terrain->setMaterialTexture(0, driver->getTexture(
                                    "../../media/terrain-texture.jpg"));
    terrain->setMaterialTexture(1, driver->getTexture(
                                    "../../media/detailmap3.jpg"));

    terrain->setMaterialType(video::EMT_DETAIL_MAP);
    terrain->scaleTexture(1.0f, 20.0f);

    int lastFPS = -1;

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

            smgr->drawAll();


            driver->endScene();

            // display frames per second in window title
            int fps = driver->getFPS();

            if (lastFPS != fps)
            {
                core::stringw str
                = L"Terrain Renderer - Irrlicht Engine [";
                str += driver->getName();
                str += "] FPS:";
                str += fps;
                device->setWindowCaption(str.c_str());
                lastFPS = fps;
            }
        }
    return 0;
}
///////////////////////
#ifndef CGRASSNODE_H
#define CGRASSNODE_H


#include <irrlicht.h>

using namespace irr;

class CGrassNode : public scene::ISceneNode
{
    public:

        CGrassNode(scene::ISceneNode* parent, scene::ISceneManager* mgr, s32 id);
        ~CGrassNode();

        virtual void OnRegisterSceneNode();
        virtual void render();




	virtual const core::aabbox3d<f32>& getBoundingBox() const;


	virtual u32 getMaterialCount();


	virtual video::SMaterial& getMaterial(u32 i);



    private:

    static const int grass=10;

    u32 totalGrass;

    core::aabbox3d<f32> Box;
   video::S3DVertex GrassModel[4*grass*grass];

	video::SMaterial Material;

    u16 indices[grass*grass*6];
	core::vector3df Positions[grass*grass];
    u8 Sizes[grass*grass];
};

#endif // CGRASSNODE_H
////////////////////
#include "cgrassnode.h"

CGrassNode::CGrassNode(scene::ISceneNode* parent, scene::ISceneManager* smgr, s32 id): scene::ISceneNode(parent, smgr, id)
{

    Material.Wireframe = false;
    Material.Lighting = false;
    Material.BackfaceCulling= false;



    core::vector3d<f32>*BBPoints=new core::vector3d<f32>[8];
    core::aabbox3d<f32> terrainBB=parent->getBoundingBox();

    terrainBB.getEdges(BBPoints);

    f32 MaxX=BBPoints[4].X;
    f32 MaxZ=BBPoints[0].Z;

    f32 MinX=BBPoints[0].X;
    f32 MinZ=BBPoints[2].Z;

    f32 lenX=MaxX-MinX;
    f32 lenZ=MaxZ-MinZ;


    f32 MaxY=BBPoints[1].Y;
    f32 MinY=BBPoints[4].Y;

    f32 lenY=MaxY-MinY;




    int counter=0;

    scene::ITriangleSelector* selector;

    selector= smgr->createTerrainTriangleSelector((scene::ITerrainSceneNode*)parent);
    parent ->setTriangleSelector(selector);

    selector->drop();

    scene::ISceneNodeAnimator* anim = smgr->createCollisionResponseAnimator(
                                          selector, smgr->getActiveCamera(), core::vector3df(6,10,6),
                                          core::vector3df(0,0,0),
                                          core::vector3df(0,50,0));
    smgr->getActiveCamera()->addAnimator(anim);
    anim->drop();

    for(s32 x=0;x<grass;x++)
    {
        float xpos= MinX+((x/float(grass))*lenX);

        for(s32 z=0;z<grass;z++)
        {

            float zpos= MinZ+((z/float(grass))*lenZ);




            core::line3d<f32> line;
            smgr->getActiveCamera()->setPosition(core::vector3df(xpos,MaxY,zpos));
            smgr->getActiveCamera()->setRotation(core::vector3df(-90,0,0));

            line.start = smgr->getActiveCamera()->getPosition();
            line.end = line.start + (smgr->getActiveCamera()->getTarget() - line.start).normalize() * 1000000;

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

            if (smgr->getSceneCollisionManager()->getCollisionPoint(
                        line, selector, intersection, tri))
            {
                Positions[counter]=intersection;
                f32 nr = tri.getNormal().Y;


                GrassModel[counter*4] = video::S3DVertex(0+intersection.X,0+intersection.Y,100+intersection.Z, 1,1,0, video::SColor(255,0,255,255), 0, 1);
                GrassModel[(counter*4)+1] = video::S3DVertex(100+intersection.X,0+intersection.Y,-10+intersection.Z, 1,0,0, video::SColor(255,255,0,255), 1, 1);
                GrassModel[(counter*4)+2] = video::S3DVertex(0+intersection.X,20+intersection.Y,0+intersection.Z, 0,1,1, video::SColor(255,255,255,0), 1, 0);
                GrassModel[(counter*4)+3] = video::S3DVertex(-100+intersection.X,0+intersection.Y,-10+intersection.Z, 0,0,1, video::SColor(255,0,255,0), 0, 0);

                counter+=1;

            }
            else
            {
                intersection= (core::vector3df(0,0,0));
               GrassModel[counter*4] = video::S3DVertex(0+intersection.X,0+intersection.Y,100+intersection.Z, 1,1,0, video::SColor(255,0,255,255), 0, 1);
                GrassModel[(counter*4)+1] = video::S3DVertex(100+intersection.X,0+intersection.Y,-10+intersection.Z, 1,0,0, video::SColor(255,255,0,255), 1, 1);
                GrassModel[(counter*4)+2] = video::S3DVertex(00+intersection.X,20+intersection.Y,0+intersection.Z, 0,1,1, video::SColor(255,255,255,0), 1, 0);
                GrassModel[(counter*4)+3] = video::S3DVertex(-100+intersection.X,0+intersection.Y,-10+intersection.Z, 0,0,1, video::SColor(255,0,255,0), 0, 0);

                counter+=1;
            }



        }
    }

    totalGrass=counter;
    for(int index=0;index<(totalGrass);index++)
    {
        indices[index*6]=index*6;
        indices[(index*6)+1]=(index*6)+1;
        indices[(index*6)+2]=(index*6)+2;

        indices[(index*6)+3]=(index*6)+2;
        indices[(index*6)+4]=index*6;
        indices[(index*6)+5]=(index*6)+3;
      printf("%d",counter);

    }


for(int index=0;index<(counter*6);index++)
    {

      printf("%d",indices[index]);

    }


    Box.reset(GrassModel[0].Pos);
    for (s32 i=0; i<totalGrass*4; i++)
        Box.addInternalPoint(GrassModel[i].Pos);

}

CGrassNode::~CGrassNode()
{
    //dtor
}

void CGrassNode::OnRegisterSceneNode()
{
    if (IsVisible)
        SceneManager->registerNodeForRendering(this);

    ISceneNode::OnRegisterSceneNode();
}


void CGrassNode::render()
{

    video::IVideoDriver* driver = SceneManager->getVideoDriver();

    driver->setMaterial(Material);
    driver->setTransform(video::ETS_WORLD, AbsoluteTransformation);
    driver->drawIndexedTriangleList(&GrassModel[0], (totalGrass*6), &indices[0],(totalGrass*2));
}

const core::aabbox3d<f32>& CGrassNode::getBoundingBox() const
{
    return Box;
}

u32 CGrassNode::getMaterialCount()
{
    return 1;
}

video::SMaterial& CGrassNode::getMaterial(u32 i)
{
    return Material;
}