bool GridAccel::IntersectP(const Ray &ray) const {
if (!gridForRefined) { // NOBOOK
rayTests.Add(0, 1); // NOBOOK
rayHits.Add(0, 1); // NOBOOK
} // NOBOOK
int rayId = ++curMailboxId;
// Check ray against overall grid bounds
float rayT;
if (bounds.Inside(ray(ray.mint)))
rayT = ray.mint;
else if (!bounds.IntersectP(ray, &rayT))
return false;
Point gridIntersect = ray(rayT);
// Set up 3D DDA for ray
float NextCrossingT[3], DeltaT[3];
int Step[3], Out[3], Pos[3];
for (int axis = 0; axis < 3; ++axis) {
// Compute current voxel for axis
Pos[axis] = PosToVoxel(gridIntersect, axis);
if (ray.d[axis] >= 0) {
// Handle ray with positive direction for voxel stepping
NextCrossingT[axis] = rayT +
(VoxelToPos(Pos[axis]+1, axis) - gridIntersect[axis]) /
ray.d[axis];
DeltaT[axis] = Width[axis] / ray.d[axis];
Step[axis] = 1;
Out[axis] = NVoxels[axis];
}
else {
// Handle ray with negative direction for voxel stepping
NextCrossingT[axis] = rayT +
(VoxelToPos(Pos[axis], axis) - gridIntersect[axis]) /
ray.d[axis];
DeltaT[axis] = -Width[axis] / ray.d[axis];
Step[axis] = -1;
Out[axis] = -1;
}
}
// Walk grid for shadow ray
for (;;) {
int offset = Offset(Pos[0], Pos[1], Pos[2]);
Voxel *voxel = voxels[offset];
if (voxel && voxel->IntersectP(ray, rayId))
return true;
// Advance to next voxel
// Find _stepAxis_ for stepping to next voxel
int bits = ((NextCrossingT[0] < NextCrossingT[1]) << 2) +
((NextCrossingT[0] < NextCrossingT[2]) << 1) +
((NextCrossingT[1] < NextCrossingT[2]));
const int cmpToAxis[8] = { 2, 1, 2, 1, 2, 2, 0, 0 };
int stepAxis = cmpToAxis[bits];
if (ray.maxt < NextCrossingT[stepAxis])
break;
Pos[stepAxis] += Step[stepAxis];
if (Pos[stepAxis] == Out[stepAxis])
break;
NextCrossingT[stepAxis] += DeltaT[stepAxis];
}
return false;
}
bool ShapeBezierSurface::Intersect(const Ray& objectRay, double* tHit, DifferentialGeometry* dg) const
{
double tHitInitial = objectRay.maxt;
double tHitShape = objectRay.maxt;
DifferentialGeometry dgShape;
//int surface = 0;
for( int surface = 0; surface < m_surfacesVector.size(); ++surface )
{
//Check if the ray intersects with the patch BoundingBox
BBox bbox = m_surfacesVector[surface]->GetComputeBBox();
bool intersectBBox = bbox.IntersectP( objectRay );
if( intersectBBox )
{
double tHitPatch;
DifferentialGeometry dgPatch;
bool intersected = m_surfacesVector[surface]->Intersect( objectRay, &tHitPatch, &dgPatch );
if( intersected && tHitShape > tHitPatch )
{
tHitShape = tHitPatch;
dgShape = dgPatch;
}
}
}
if( tHitShape < tHitInitial )
{
dgShape.pShape = this;
*tHit = tHitShape;
*dg = dgShape;
return true;
}
return false;
}
bool KdTreeAccel::IntersectP(const Ray &ray) const {
// Compute initial parametric range of ray inside kd-tree extent
float tmin, tmax;
if (!bounds.IntersectP(ray, &tmin, &tmax))
return false;
// Prepare to traverse kd-tree for ray
int rayId = curMailboxId++;
Vector invDir(1.f/ray.d.x, 1.f/ray.d.y, 1.f/ray.d.z);
#define MAX_TODO 64
KdToDo todo[MAX_TODO];
int todoPos = 0;
const KdAccelNode *node = &nodes[0];
while (node != NULL) {
// Update kd-tree shadow ray traversal statistics
//static StatsCounter nodesTraversed("Kd-Tree Accelerator",
// "Number of kd-tree nodes traversed by shadow rays");
//++nodesTraversed;
if (node->IsLeaf()) {
// Check for shadow ray intersections inside leaf node
u_int nPrimitives = node->nPrimitives();
if (nPrimitives == 1) {
MailboxPrim *mp = node->onePrimitive;
if (mp->lastMailboxId != rayId) {
mp->lastMailboxId = rayId;
if (mp->primitive->IntersectP(ray))
return true;
}
}
else {
MailboxPrim **prims = node->primitives;
for (u_int i = 0; i < nPrimitives; ++i) {
MailboxPrim *mp = prims[i];
if (mp->lastMailboxId != rayId) {
mp->lastMailboxId = rayId;
if (mp->primitive->IntersectP(ray))
return true;
}
}
}
// Grab next node to process from todo list
if (todoPos > 0) {
--todoPos;
node = todo[todoPos].node;
tmin = todo[todoPos].tmin;
tmax = todo[todoPos].tmax;
}
else
break;
}
else {
// Process kd-tree interior node
// Compute parametric distance along ray to split plane
int axis = node->SplitAxis();
float tplane = (node->SplitPos() - ray.o[axis]) *
invDir[axis];
// Get node children pointers for ray
const KdAccelNode *firstChild, *secondChild;
int belowFirst = (ray.o[axis] < node->SplitPos()) ||
(ray.o[axis] == node->SplitPos() && ray.d[axis] >= 0);
if (belowFirst) {
firstChild = node + 1;
secondChild = &nodes[node->aboveChild];
}
else {
firstChild = &nodes[node->aboveChild];
secondChild = node + 1;
}
// Advance to next child node, possibly enqueue other child
if (tplane > tmax || tplane <= 0)
node = firstChild;
else if (tplane < tmin)
node = secondChild;
else {
// Enqueue _secondChild_ in todo list
todo[todoPos].node = secondChild;
todo[todoPos].tmin = tplane;
todo[todoPos].tmax = tmax;
++todoPos;
node = firstChild;
tmax = tplane;
}
}
}
return false;
}
