顺便说一下,这是我最终采用的Revelles论文实现:
#include "octree_traversal.h"
using namespace std;
unsigned char a;
int first_node(double tx0, double ty0, double tz0, double txm, double tym, double tzm){
unsigned char answer = 0;
if(tx0 > ty0){
if(tx0 > tz0){
if(tym < tx0) answer|=2;
if(tzm < tx0) answer|=1;
return (int) answer;
}
}
else {
if(ty0 > tz0){
if(txm < ty0) answer|=4;
if(tzm < ty0) answer|=1;
return (int) answer;
}
}
if(txm < tz0) answer|=4;
if(tym < tz0) answer|=2;
return (int) answer;
}
int new_node(double txm, int x, double tym, int y, double tzm, int z){
if(txm < tym){
if(txm < tzm){return x;}
}
else{
if(tym < tzm){return y;}
}
return z;
}
void proc_subtree (double tx0, double ty0, double tz0, double tx1, double ty1, double tz1, Node* node){
float txm, tym, tzm;
int currNode;
if(tx1 < 0 || ty1 < 0 || tz1 < 0) return;
if(node->terminal){
cout << "Reached leaf node " << node->debug_ID << endl;
return;
}
else{ cout << "Reached node " << node->debug_ID << endl;}
txm = 0.5*(tx0 + tx1);
tym = 0.5*(ty0 + ty1);
tzm = 0.5*(tz0 + tz1);
currNode = first_node(tx0,ty0,tz0,txm,tym,tzm);
do{
switch (currNode)
{
case 0: {
proc_subtree(tx0,ty0,tz0,txm,tym,tzm,node->children[a]);
currNode = new_node(txm,4,tym,2,tzm,1);
break;}
case 1: {
proc_subtree(tx0,ty0,tzm,txm,tym,tz1,node->children[1^a]);
currNode = new_node(txm,5,tym,3,tz1,8);
break;}
case 2: {
proc_subtree(tx0,tym,tz0,txm,ty1,tzm,node->children[2^a]);
currNode = new_node(txm,6,ty1,8,tzm,3);
break;}
case 3: {
proc_subtree(tx0,tym,tzm,txm,ty1,tz1,node->children[3^a]);
currNode = new_node(txm,7,ty1,8,tz1,8);
break;}
case 4: {
proc_subtree(txm,ty0,tz0,tx1,tym,tzm,node->children[4^a]);
currNode = new_node(tx1,8,tym,6,tzm,5);
break;}
case 5: {
proc_subtree(txm,ty0,tzm,tx1,tym,tz1,node->children[5^a]);
currNode = new_node(tx1,8,tym,7,tz1,8);
break;}
case 6: {
proc_subtree(txm,tym,tz0,tx1,ty1,tzm,node->children[6^a]);
currNode = new_node(tx1,8,ty1,8,tzm,7);
break;}
case 7: {
proc_subtree(txm,tym,tzm,tx1,ty1,tz1,node->children[7^a]);
currNode = 8;
break;}
}
} while (currNode<8);
}
void ray_octree_traversal(Octree* octree, Ray ray){
a = 0;
if(ray.direction[0] < 0){
ray.origin[0] = octree->center[0] * 2 - ray.origin[0];
ray.direction[0] = - ray.direction[0];
a |= 4 ;
}
if(ray.direction[1] < 0){
ray.origin[1] = octree->center[1] * 2 - ray.origin[1];
ray.direction[1] = - ray.direction[1];
a |= 2 ;
}
if(ray.direction[2] < 0){
ray.origin[2] = octree->center[2] * 2 - ray.origin[2];
ray.direction[2] = - ray.direction[2];
a |= 1 ;
}
double divx = 1 / ray.direction[0];
double divy = 1 / ray.direction[1];
double divz = 1 / ray.direction[2];
double tx0 = (octree->min[0] - ray.origin[0]) * divx;
double tx1 = (octree->max[0] - ray.origin[0]) * divx;
double ty0 = (octree->min[1] - ray.origin[1]) * divy;
double ty1 = (octree->max[1] - ray.origin[1]) * divy;
double tz0 = (octree->min[2] - ray.origin[2]) * divz;
double tz1 = (octree->max[2] - ray.origin[2]) * divz;
if( max(max(tx0,ty0),tz0) < min(min(tx1,ty1),tz1) ){
proc_subtree(tx0,ty0,tz0,tx1,ty1,tz1,octree->root);
}
}