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extended TAABB::rayIntersect function

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Wenzel Jakob 2013-09-10 18:43:44 +02:00
parent 0ccb7211df
commit db35564b01
1 changed files with 68 additions and 2 deletions
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70
include/mitsuba/core/aabb.h
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@ -292,6 +292,11 @@ template <typename T> struct TAABB {
/** \brief Calculate the near and far ray-AABB intersection
* points (if they exist).
*
* The parameters \c nearT and \c farT are used to return the
* ray distances to the intersections (including negative distances).
* Any previously contained value is overwritten, even if there was
* no intersection.
*
* \remark In the Python bindings, this function returns the
* \c nearT and \c farT values as a tuple (or \c None, when no
* intersection was found)
@ -302,11 +307,10 @@ template <typename T> struct TAABB {
/* For each pair of AABB planes */
for (int i=0; i<PointType::dim; i++) {
const Float direction = ray.d[i];
const Float origin = ray.o[i];
const Float minVal = min[i], maxVal = max[i];
if (direction == 0) {
if (ray.d[i] == 0) {
/* The ray is parallel to the planes */
if (origin < minVal || origin > maxVal)
return false;
@ -329,6 +333,68 @@ template <typename T> struct TAABB {
return true;
}
/** \brief Calculate the overlap between an axis-aligned bounding box
* and a ray segment
*
* This function is an extended version of the simpler \ref rayIntersect command
* provided above. The first change is that input values passed via
* the \c nearT and \c farT parameters are considered to specify a query interval.
*
* This interval is intersected against the bounding box, returning the remaining
* interval using the \c nearT and \c farT parameters. Furthermore, the
* interval endpoints are also returned as 3D positions via the \c near and
* \c far parameters. Special care is taken to reduce round-off errors.
*
* \remark Not currently exposed via the Python bindings
*/
FINLINE bool rayIntersect(const Ray &ray, Float &nearT, Float &farT, Point &near, Point &far) const {
int nearAxis = -1, farAxis = -1;
/* For each pair of AABB planes */
for (int i=0; i<PointType::dim; i++) {
const Float origin = ray.o[i];
const Float minVal = min[i], maxVal = max[i];
if (ray.d[i] == 0) {
/* The ray is parallel to the planes */
if (origin < minVal || origin > maxVal)
return false;
} else {
/* Calculate intersection distances */
Float t1 = (minVal - origin) * ray.dRcp[i];
Float t2 = (maxVal - origin) * ray.dRcp[i];
bool flip = t1 > t2;
if (flip)
std::swap(t1, t2);
if (t1 > nearT) {
nearT = t1;
nearAxis = flip ? (i + PointType::dim) : i;
}
if (t2 < farT) {
farT = t2;
farAxis = flip ? i : (i + PointType::dim);
}
}
}
if (!(nearT <= farT))
return false;
near = ray(nearT); far = ray(farT);
/* Avoid roundoff errors on the component where the intersection took place */
if (nearAxis >= 0)
near[nearAxis % PointType::dim] = ((Float *) this)[nearAxis];
if (farAxis >= 0)
far[farAxis % PointType::dim] = ((Float *) this)[farAxis];
return true;
}
/// Serialize this bounding box to a binary data stream
inline void serialize(Stream *stream) const {
min.serialize(stream);