En gros tu veux que j'arrive a un truc comme ca ?

void            Map::constructMap(float lenght, float width, irr::video::IVideoDriver *driver, irr::scene::ISceneManager *sceneManager)
{
  Terrain_ = sceneManager->addTerrainSceneNode("./ressources/HeightMap.bmp", 0, -1, irr::core::vector3df(0.f, 0.f, 0.f), irr::core::vector3df(0.f, 0.f, 0.f), irr::core::vector3df(lenght, 0.0f, width), irr::video::SColor ( 255, 255, 255, 255 ), 5, irr::scene::ETPS_17, 3);

  Terrain_->setMaterialFlag(irr::video::EMF_LIGHTING, true);
  Terrain_->setMaterialFlag(irr::video::EMF_ANISOTROPIC_FILTER , true);
  Terrain_->setMaterialTexture(0, driver->getTexture("./ressources/terrdirtgrass.jpg"));

  Terrain_->setPosition(irr::core::vector3df(0, 0 , 0));
  Terrain_->scaleTexture( 1.063f * lenght, 0.0f);
  mapSizeX_ = lenght;
  mapSizeZ_ = width;
}