OpenVDB  9.0.1
Public Types | Public Member Functions | List of all members
VolumeRayIntersector< GridT, NodeLevel, RayT > Class Template Reference

This class provides the public API for intersecting a ray with a generic (e.g. density) volume. More...

#include <openvdb/tools/RayIntersector.h>

Public Types

using GridType = GridT
 
using RayType = RayT
 
using RealType = typename RayT::RealType
 
using RootType = typename GridT::TreeType::RootNodeType
 
using TreeT = tree::Tree< typename RootType::template ValueConverter< bool >::Type >
 

Public Member Functions

 VolumeRayIntersector (const GridT &grid, int dilationCount=0)
 Grid constructor. More...
 
 VolumeRayIntersector (const GridT &grid, const math::CoordBBox &bbox)
 Grid and BBox constructor. More...
 
 VolumeRayIntersector (const VolumeRayIntersector &other)
 Shallow copy constructor. More...
 
 ~VolumeRayIntersector ()
 Destructor. More...
 
bool setIndexRay (const RayT &iRay)
 Return false if the index ray misses the bbox of the grid. More...
 
bool setWorldRay (const RayT &wRay)
 Return false if the world ray misses the bbox of the grid. More...
 
RayT::TimeSpan march ()
 
bool march (RealType &t0, RealType &t1)
 Return true if the ray intersects active values, i.e. either active voxels or tiles. Only when a hit is detected are t0 and t1 updated with the corresponding entry and exit times along the INDEX ray! More...
 
template<typename ListType >
void hits (ListType &list)
 Generates a list of hits along the ray. More...
 
Vec3R getIndexPos (RealType time) const
 Return the floating-point index position along the current index ray at the specified time. More...
 
Vec3R getWorldPos (RealType time) const
 Return the floating-point world position along the current index ray at the specified time. More...
 
RealType getWorldTime (RealType time) const
 
const GridT & grid () const
 Return a const reference to the input grid. More...
 
const TreeTtree () const
 Return a const reference to the (potentially dilated) bool tree used to accelerate the ray marching. More...
 
const math::CoordBBoxbbox () const
 Return a const reference to the BBOX of the grid. More...
 
void print (std::ostream &os=std::cout, int verboseLevel=1)
 Print bbox, statistics, memory usage and other information. More...
 

Detailed Description

template<typename GridT, int NodeLevel = GridT::TreeType::RootNodeType::ChildNodeType::LEVEL, typename RayT = math::Ray<Real>>
class openvdb::v9_0::tools::VolumeRayIntersector< GridT, NodeLevel, RayT >

This class provides the public API for intersecting a ray with a generic (e.g. density) volume.

Internally it performs the actual hierarchical tree node traversal.

Warning
Use the (default) copy-constructor to make sure each computational thread has their own instance of this class. This is important since it contains a ValueAccessor that is not thread-safe and a CoordBBox of the active voxels that should not be re-computed for each thread. However copying is very efficient.
Example:
// Create an instance for the master thread
// For each additional thread use the copy constructor. This
// amortizes the overhead of computing the bbox of the active voxels!
VolumeRayIntersector inter2(inter);
// Before each ray-traversal set the index ray.
iter.setIndexRay(ray);
// or world ray
iter.setWorldRay(ray);
// Now you can begin the ray-marching using consecutive calls to VolumeRayIntersector::march
double t0=0, t1=0;// note the entry and exit times are with respect to the INDEX ray
while ( inter.march(t0, t1) ) {
// perform line-integration between t0 and t1
}}

Member Typedef Documentation

using GridType = GridT
using RayType = RayT
using RealType = typename RayT::RealType
using RootType = typename GridT::TreeType::RootNodeType
using TreeT = tree::Tree<typename RootType::template ValueConverter<bool>::Type>

Constructor & Destructor Documentation

VolumeRayIntersector ( const GridT &  grid,
int  dilationCount = 0 
)
inline

Grid constructor.

Parameters
gridGeneric grid to intersect rays against.
dilationCountThe number of voxel dilations performed on (a boolean copy of) the input grid. This allows the intersector to account for the size of interpolation kernels in client code.
Exceptions
RuntimeErrorif the voxels of the grid are not uniform or the grid is empty.
VolumeRayIntersector ( const GridT &  grid,
const math::CoordBBox bbox 
)
inline

Grid and BBox constructor.

Parameters
gridGeneric grid to intersect rays against.
bboxThe axis-aligned bounding-box in the index space of the grid.
Warning
It is assumed that bbox = (min, min + dim) where min denotes to the smallest grid coordinates and dim are the integer length of the bbox.
Exceptions
RuntimeErrorif the voxels of the grid are not uniform or the grid is empty.
VolumeRayIntersector ( const VolumeRayIntersector< GridT, NodeLevel, RayT > &  other)
inline

Shallow copy constructor.

Warning
This copy constructor creates shallow copies of data members of the instance passed as the argument. For performance reasons we are not using shared pointers (their mutex-lock impairs multi-threading).
~VolumeRayIntersector ( )
inline

Destructor.

Member Function Documentation

const math::CoordBBox& bbox ( ) const
inline

Return a const reference to the BBOX of the grid.

Vec3R getIndexPos ( RealType  time) const
inline

Return the floating-point index position along the current index ray at the specified time.

Vec3R getWorldPos ( RealType  time) const
inline

Return the floating-point world position along the current index ray at the specified time.

RealType getWorldTime ( RealType  time) const
inline
const GridT& grid ( ) const
inline

Return a const reference to the input grid.

void hits ( ListType &  list)
inline

Generates a list of hits along the ray.

Parameters
listList of hits represented as time spans.
Note
ListType is a list of RayType::TimeSpan and is required to have the two methods: clear() and push_back(). Thus, it could be std::vector<typename RayType::TimeSpan> or std::deque<typename RayType::TimeSpan>.
RayT::TimeSpan march ( )
inline
bool march ( RealType t0,
RealType t1 
)
inline

Return true if the ray intersects active values, i.e. either active voxels or tiles. Only when a hit is detected are t0 and t1 updated with the corresponding entry and exit times along the INDEX ray!

Note
Note that t0 and t1 are only resolved at the node level (e.g. a LeafNode with active voxels) as opposed to the individual active voxels.
Parameters
t0If the return value > 0 this is the time of the first hit of an active tile or leaf.
t1If the return value > t0 this is the time of the first hit (> t0) of an inactive tile or exit point of the BBOX for the leaf nodes.
Warning
t0 and t1 are computed with respect to the ray represented in index space of the current grid, not world space!
void print ( std::ostream &  os = std::cout,
int  verboseLevel = 1 
)
inline

Print bbox, statistics, memory usage and other information.

Parameters
osa stream to which to write textual information
verboseLevel1: print bbox only; 2: include boolean tree statistics; 3: include memory usage
bool setIndexRay ( const RayT &  iRay)
inline

Return false if the index ray misses the bbox of the grid.

Parameters
iRayRay represented in index space.
Warning
Call this method (or setWorldRay) before the ray traversal starts and use the return value to decide if further marching is required.
bool setWorldRay ( const RayT &  wRay)
inline

Return false if the world ray misses the bbox of the grid.

Parameters
wRayRay represented in world space.
Warning
Call this method (or setIndexRay) before the ray traversal starts and use the return value to decide if further marching is required.

Since hit times are computed with respect to the ray represented in index space of the current grid, it is recommended that either the client code uses getIndexPos to compute index position from hit times or alternatively keeps an instance of the index ray and instead uses setIndexRay to initialize the ray.

const TreeT& tree ( ) const
inline

Return a const reference to the (potentially dilated) bool tree used to accelerate the ray marching.