/*==========================================================================
 *	(C) 2006 Universitat Jaume I
 *==========================================================================
 *	PROYECT:	GAME TOOLS
 *==========================================================================
 *	CONTENT:
 *
 *
 *	@file	GeoLodManager.cpp
 *===========================================================================*/

#include "GeoLodManager.h"
#include "GeoLodObject.h"

namespace Geometry
{
	class lodobj_idpos_node_t
	{
	public:
		lodobj_idpos_node_t(LodObject *o):lodobj(o),must_recalculate_distance(true),dist2cam(0.0f){}
		LodObject *lodobj;
		float dist2cam; // used to index the lodobj in the other map
		bool must_recalculate_distance;
		bool operator < (const lodobj_idpos_node_t &o) const { return (lodobj->GetUniqueID()<o.lodobj->GetUniqueID()); }
	};
}

using namespace Geometry;

LodManager::LodManager(float near, float far, const Geometry::Vector3 &campos)
:targetFPS(30),camera_changed(true),camera_pos(campos),
 near_range(near),far_range(far)
{
}

void Geometry::LodManager::AddLodObj(LodObject * o, const Geometry::Vector3 &p)
{
	float dist = CalculateDistToCamera(p);	
	lodobj_dists[dist] = lodobj_dist_node_t(o);
	UpdateLODObjectPos(o,p);
}


void Geometry::LodManager::UpdateLOD(void)
{
	// recalculate distances if have to
	if (camera_changed)
	{
		// if the camera has changed, recalculate all lodobject distances to it		
		lodobj_dists.clear();
		for (std::map<Geometry::lodobj_idpos_node_t,Geometry::Vector3>::iterator it = lodobj_pos.begin(); it != lodobj_pos.end(); it++)
		{
			const lodobj_idpos_node_t & posnode = it->first;
			const Vector3 & pos = it->second;
			float newdist = CalculateDistToCamera(pos);
			lodobj_dists[newdist] = lodobj_dist_node_t(posnode.lodobj);
		}
		camera_changed=false;
	}
	else
	{
		// if any of the objects changed its position, the distance must be recalculated
		for (std::map<Geometry::lodobj_idpos_node_t,Geometry::Vector3>::iterator it = lodobj_pos.begin(); it != lodobj_pos.end(); it++)
		{
			const lodobj_idpos_node_t & posnode = it->first;
			if (posnode.must_recalculate_distance)
			{
				const Vector3 & pos = it->second;
				float newdist = CalculateDistToCamera(pos);
				lodobj_dists[newdist] = lodobj_dist_node_t(posnode.lodobj);
/*				lodobj_dists.erase(it);*/
			}
		}
	}

	// select a tree to change its LOD
	float random_dist = SelectRandomDistance();
	std::map<float,Geometry::lodobj_dist_node_t>::iterator nearest = lodobj_dists.upper_bound(random_dist);
}

void Geometry::LodManager::UpdateCamera(const Geometry::Vector3 &p)
{
	camera_pos = p;
	camera_changed = true;
}

void Geometry::LodManager::UpdateLODObjectPos(LodObject *o, const Geometry::Vector3 &p)
{
	lodobj_pos[lodobj_idpos_node_t(o)] = p;
}


float Geometry::LodManager::CalculateDistToCamera(const Geometry::Vector3 &p) const
{
	return camera_pos.dotProduct(p);
}

float Geometry::LodManager::SelectRandomDistance(void) const
{
	float linear_01 = (float)rand()/(float)RAND_MAX;
	float exp_01 = linear_01*linear_01;
	float real_dist = exp_01*near_range + (1.0f-exp_01)*far_range;
	return real_dist;
}