//OK
//irradiance_estimate computes an irradiance estimate
// at a given surface position
public RGBColor IrradianceEstimate(Point3D pos, Vector3D normal, float max_dist, int nphotons)
{
RGBColor irrad = RGBColor.Black;
NearestPhotons np = new NearestPhotons();
np.Dist2 = new float[nphotons + 1];
np.Index = new Photon[nphotons + 1];
np.Pos = pos;
np.Max = nphotons;
np.Found = 0;
np.GotHeap = 0;
np.Dist2[0] = max_dist * max_dist;
// locate the nearest photons
this.LocatePhotons(np, 1);
// if less than 8 photons return
if (np.Found < 8)
{
return(irrad);
}
Vector3D pdir;
// sum irradiance from all photons
for (int i = 1; i <= np.Found; i++)
{
Photon p = np.Index[i];
// the photon_dir call and following if can be omitted (for speed)
// if the scene does not have any thin surfaces
pdir = this.photonDir(p);
if ((pdir * normal) < 0.0f)
{
irrad += p.Power;
}
}
float tmp = (float)((1.0f / Math.PI) / (np.Dist2[0])); // estimate of
// density
irrad *= tmp;
//Use Array.Clear();
np.Dist2 = null;
np.Index = null;
return(irrad);
}
//OK
// locate_photons finds the nearest photons in the
// photon map given the parameters in np
private void LocatePhotons(NearestPhotons np, int index)
{
Photon p = this.Photons[index];
if (index < this.half_stored_photons) {
float dist1 = np.Pos[p.Plane] - p.Position[p.Plane];
if (dist1 > 0.0) {
// if dist1 is positive search right plane
this.LocatePhotons(np, 2 * index + 1);
if (dist1 * dist1 < np.Dist2[0]) {
this.LocatePhotons(np, 2 * index);
}
} else {
// dist1 is negative search left first
this.LocatePhotons(np, 2 * index);
if (dist1 * dist1 < np.Dist2[0]) {
this.LocatePhotons(np, 2 * index + 1);
}
}
}
// compute squared distance between current photon and np.pos
//dist1 = p.pos[0] - np.pos[0];
//float dist2 = dist1 * dist1;
//dist1 = p.pos[1] - np.pos[1];
//dist2 += dist1 * dist1;
//dist1 = p.pos[2] - np.pos[2];
//dist2 += dist1 * dist1;
float dist2 = (p.Position - np.Pos).Length2;
if (dist2 < np.Dist2[0]) {
// we found a photon :) Insert it in the candidate list
if (np.Found < np.Max) {
// heap is not full; use array
np.Found++;
np.Dist2[np.Found] = dist2;
np.Index[np.Found] = p;
} else {
int j, parent;
if (np.GotHeap == 0) {
// Do we need to build the heap?
// Build heap
float dst2;
Photon phot;
int half_found = np.Found >> 1;
for (int k = half_found; k >= 1; k--) {
parent = k;
phot = np.Index[k];
dst2 = np.Dist2[k];
while (parent <= half_found) {
j = parent + parent;
if (j < np.Found && np.Dist2[j] < np.Dist2[j + 1]) {
j++;
}
if (dst2 >= np.Dist2[j]) {
break;
}
np.Dist2[parent] = np.Dist2[j];
np.Index[parent] = np.Index[j];
parent = j;
}
np.Dist2[parent] = dst2;
np.Index[parent] = phot;
}
np.GotHeap = 1;
}
// insert new photon into max heap
// delete largest element, insert new and reorder the heap
parent = 1;
j = 2;
while (j <= np.Found) {
if (j < np.Found && np.Dist2[j] < np.Dist2[j + 1]) {
j++;
}
if (dist2 > np.Dist2[j]) {
break;
}
np.Dist2[parent] = np.Dist2[j];
np.Index[parent] = np.Index[j];
parent = j;
j += j;
}
if (dist2 < np.Dist2[parent]) {
np.Index[parent] = p;
np.Dist2[parent] = dist2;
}
np.Dist2[0] = np.Dist2[1];
}
}
}
//OK
// locate_photons finds the nearest photons in the
// photon map given the parameters in np
private void LocatePhotons(NearestPhotons np, int index)
{
Photon p = this.Photons[index];
if (index < this.half_stored_photons)
{
float dist1 = np.Pos[p.Plane] - p.Position[p.Plane];
if (dist1 > 0.0)
{
// if dist1 is positive search right plane
this.LocatePhotons(np, 2 * index + 1);
if (dist1 * dist1 < np.Dist2[0])
{
this.LocatePhotons(np, 2 * index);
}
}
else
{
// dist1 is negative search left first
this.LocatePhotons(np, 2 * index);
if (dist1 * dist1 < np.Dist2[0])
{
this.LocatePhotons(np, 2 * index + 1);
}
}
}
// compute squared distance between current photon and np.pos
//dist1 = p.pos[0] - np.pos[0];
//float dist2 = dist1 * dist1;
//dist1 = p.pos[1] - np.pos[1];
//dist2 += dist1 * dist1;
//dist1 = p.pos[2] - np.pos[2];
//dist2 += dist1 * dist1;
float dist2 = (p.Position - np.Pos).Length2;
if (dist2 < np.Dist2[0])
{
// we found a photon :) Insert it in the candidate list
if (np.Found < np.Max)
{
// heap is not full; use array
np.Found++;
np.Dist2[np.Found] = dist2;
np.Index[np.Found] = p;
}
else
{
int j, parent;
if (np.GotHeap == 0)
{
// Do we need to build the heap?
// Build heap
float dst2;
Photon phot;
int half_found = np.Found >> 1;
for (int k = half_found; k >= 1; k--)
{
parent = k;
phot = np.Index[k];
dst2 = np.Dist2[k];
while (parent <= half_found)
{
j = parent + parent;
if (j < np.Found && np.Dist2[j] < np.Dist2[j + 1])
{
j++;
}
if (dst2 >= np.Dist2[j])
{
break;
}
np.Dist2[parent] = np.Dist2[j];
np.Index[parent] = np.Index[j];
parent = j;
}
np.Dist2[parent] = dst2;
np.Index[parent] = phot;
}
np.GotHeap = 1;
}
// insert new photon into max heap
// delete largest element, insert new and reorder the heap
parent = 1;
j = 2;
while (j <= np.Found)
{
if (j < np.Found && np.Dist2[j] < np.Dist2[j + 1])
{
j++;
}
if (dist2 > np.Dist2[j])
{
break;
}
np.Dist2[parent] = np.Dist2[j];
np.Index[parent] = np.Index[j];
parent = j;
j += j;
}
if (dist2 < np.Dist2[parent])
{
np.Index[parent] = p;
np.Dist2[parent] = dist2;
}
np.Dist2[0] = np.Dist2[1];
}
}
}
//OK
//irradiance_estimate computes an irradiance estimate
// at a given surface position
public RGBColor IrradianceEstimate(Point3D pos, Vector3D normal, float max_dist, int nphotons)
{
RGBColor irrad = RGBColor.Black;
NearestPhotons np = new NearestPhotons();
np.Dist2 = new float[nphotons + 1];
np.Index = new Photon[nphotons + 1];
np.Pos = pos;
np.Max = nphotons;
np.Found = 0;
np.GotHeap = 0;
np.Dist2[0] = max_dist * max_dist;
// locate the nearest photons
this.LocatePhotons(np, 1);
// if less than 8 photons return
if (np.Found < 8) {
return irrad;
}
Vector3D pdir;
// sum irradiance from all photons
for (int i = 1; i <= np.Found; i++) {
Photon p = np.Index[i];
// the photon_dir call and following if can be omitted (for speed)
// if the scene does not have any thin surfaces
pdir = this.photonDir(p);
if ((pdir * normal) < 0.0f) {
irrad += p.Power;
}
}
float tmp = (float) ((1.0f / Math.PI) / (np.Dist2[0])); // estimate of
// density
irrad *= tmp;
//Use Array.Clear();
np.Dist2 = null;
np.Index = null;
return irrad;
}
