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Untested first draft.

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Federico Ponchio 2004-04-01 11:33:41 +00:00
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/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
/****************************************************************************
History
$Log: not supported by cvs2svn $
****************************************************************************/
#ifndef VCG_MT_H
#define VCG_MT_H
#include <vector>
#include <queue>
#include <map>
#include <vcg/space/sphere3.h>
#include <vcg/space/point3.h>
#include <wrap/gui/frustum.h>
namespace vcg {
/** \addtogroup mt */
/*@{*/
/**
The templated class for representing a mt structure.
The class is templated over the Cell class which MUST implement this functions:
float Error();
float Distance(Cell &c, Point3f &p);
see mt_file.h for an example.
*/
template <class C> class MT {
public:
typedef C Cell;
private:
class Frag:public std::vector<Cell *> {};
struct Node {
std::vector<Node *> in;
std::vector<Node *> out;
std::vector<Frag> frags;
float error;
bool visited;
};
std::vector<Node> nodes;
public:
/** Update class for defining the history.
Notice how the Update class holds pointers.
You are responsible of holding the Cell structure and rebuild the structure
if the pointers change.
*/
class Update {
public:
std::vector<Cell *> erased;
std::vector<Cell *> created;
};
///build mt strucure from a sequence of updates.
void Load(std::vector<Update> &updates) {
//The last update erases everything.
assert(updates[0].erased.size() == 0);
//maps cell -> node containing it
std::map<Cell *, unsigned int> cell_node;
nodes.resize(updates.size());
//building fragments and nodes.
unsigned int current_node = 0;
std::vector<Update>::iterator u;
for(u = updates.begin(); u != updates.end(); u++) {
Node &node = nodes[current_node];
node.error = 0;
//created cells belong to this node, we look also for max error.
for(unsigned int i = 0; i < (*u).created.size(); i++) {
Cell *cell = (*u).created[i];
if(cell->Error() > node.error)
node.error = cell->Error();
cell_node[cell] = current_node;
}
//Every erased cell already belonged to a node.
//we record for each node its cells.
std::map<unsigned int, std::vector<Cell *> > node_erased;
for(unsigned int i = 0; i < (*u).erased.size(); i++) {
Cell *cell = (*u).erased[i];
assert(cell_node.count(cell));
node_erased[cell_node[cell]].push_back(cell);
}
//for every node with erased cells we build a frag and put the corresponding cells in it.
std::map<unsigned int, std::vector<Cell *> >::iterator e;
for(e = node_erased.begin(); e != node_erased.end(); e++) {
//Build a new Frag.
Frag fr;
float max_err = -1;
//Fill it with erased cells.
std::vector<Cell *> &cells = (*e).second;
std::vector<Cell *>::iterator k;
for(k = cells.begin(); k != cells.end(); k++) {
Cell *cell = (*k);
fr.push_back(cell);
if(cell->Error() > max_err)
max_err = cell->Error();
}
//Add the new Frag to the node.
unsigned int floor_node = (*e).first;
Node &oldnode = nodes[floor_node];
oldnode.frags.push_back(fr);
if(node.error < max_err)
node.error = max_err;
//Update in and out of the nodes.
node.in.push_back(&oldnode);
oldnode.out.push_back(&node);
}
current_node++;
}
}
void Clear() {
nodes.clear();
}
///error based extraction
template <class CONT> void Extract(CONT &selected, float error) {
std::vector<Node>::iterator n;
for(n = nodes.begin(); n != nodes.end(); n++)
(*n).visited = false;
std::queue<Node *> qnodo;
qnodo.push(&nodes[0]);
nodes[0].visited = true;
for( ; !qnodo.empty(); qnodo.pop()) {
Node &node = *qnodo.front();
std::vector<Frag>::iterator fragment;
std::vector<Node *>::iterator on;
for(on = node.out.begin(), fragment = node.frags.begin(); on != node.out.end(); ++on, ++fragment) {
if((*on)->visited) continue;
if(error < (*on)->error) { //need to expand this node.
qnodo.push(*on);
(*on)->visited = 1;
} else {
vector<Cell *>::iterator cell;
for(cell=(*fragment).begin(); cell != (*fragment).end(); ++cell)
selected.push_back(*cell);
}
}
}
}
//custom extraction
template <class CONT, class POLICY> void Extract(CONT &selected, POLICY &policy) {
std::vector<Node>::iterator n;
for(n = nodes.begin(); n != nodes.end(); n++)
(*n).visited = false;
std::queue<Node *> qnodo;
qnodo.push(&nodes[0]);
nodes[0].visited = true;
for( ; !qnodo.empty(); qnodo.pop()) {
Node &node = *qnodo.front();
std::vector<Frag>::iterator i;
std::vector<Node *>::iterator on;
for(i = node.frags.begin(), on = node.out.begin(); i != node.frags.end(); i++, on++) {
if((*on)->visited) continue;
Frag &frag = (*i);
std::vector<Cell *>::iterator cell;
for(cell = frag.begin(); cell != frag.end(); cell++) {
if(policy.Expand(*cell))
visit(*on, qnodo);
}
}
}
Extract(selected);
}
//extract using a user class which must provides:
//bool refineCell(Cell *cell, Frustum &frustum);
//void addCell(Cell *cell);
//void removeCell(Cell *cell);
//template <class CONT> void extract(std::vector<Cell *> &selected, Frustum &frustum, T &error);
///extract using the visited flag in nodes to a STL container of Cell *
template <class CONT> void Extract(CONT &selected) {
selected.clear();
std::vector<Node>::iterator i;
for(i = nodes.begin(); i != nodes.end(); i++) {
Node &node = *i;
if(!node.visited)
continue;
std::vector<Node *>::iterator n;
std::vector<Frag>::iterator f;
for(n = node.out.begin(), f = node.frags.begin(); n != node.out.end(); n++, f++) {
if(!(*n)->visited || (*n)->error == 0) {
vector<Cell *>::iterator c;
Frag &frag = (*f);
for(c = frag.begin(); c != frag.end(); c++)
selected.insert(selected.end(), *c);
}
}
}
}
///add a node to the queue recursively mantaining coherence.
void Visit(Node *node, std::queue<Node *> &qnode) {
std::vector<Node *>::iterator n;
for(n = node->in.begin(); n != node->in.end(); n++)
if(!(*n)->visited)
visit(*n, qnode);
node->visited = true;
qnode.push(node);
}
};
template <class C> class FrustumPolicy {
public:
typedef C Cell;
Frustumf frustum;
///target error in screen space (pixels)
float error;
bool Expand(Cell *cell) {
if(cell->Error() == 0) return false;
float dist = Distance(*cell, frustum.ViewPoint());
/*Point3f line = frustum.viewPoint() - cell->sphere.center;
float dist = line.Norm() - cell->sphere.radius; */
if(dist < 0) return true;
dist = pow(dist, 1.2);
float res = cell->Error() / (frustum.Resolution()*dist);
return res;
}
};
///really simple example policy
template <class C> class DiracPolicy {
public:
typedef C Cell;
Point3f focus;
///max error in object space at distance 0
float error;
DiracPolicy(Point3f &f = Point3f(0, 0, 0), float e = 0): focus(f), error(e) {}
bool Expand(Cell *cell) {
if(cell->Error() == 0) return false;
float dist = Distance(*cell, focus);
if(dist > 0) return true;
return false;
}
};
}//namespace vcg
#endif