OpenVDB: PointTreeMarcher< AccT, RayT, CoordT > Class Template Reference

OpenVDB 9.1.0

Public Types | Public Member Functions | List of all members
PointTreeMarcher< AccT, RayT, CoordT > Class Template Reference

A Tree Marcher for Point Grids. More...

`#include <nanovdb/util/HDDA.h>`

Inheritance diagram for PointTreeMarcher< AccT, RayT, CoordT >:

## Public Types
using | ChildT = typename NodeT::ChildNodeType
using | RealType = typename RayT::RealType
using | RealT = RealType
using | CoordType = Coord

## Public Member Functions
__hostdev__ | PointTreeMarcher (AccT &acc)
__hostdev__ bool | init (RayT ray)
| Initiates this instance with a ray in index space. More...
__hostdev__ bool | init (const RayT &indexRay)
| Initialize the TreeMarcher with an index-space ray. More...
__hostdev__ bool | step (const LeafNode< AccT::ValueType > **node, float &t0, float &t1)
| step the ray through the tree. If the ray hits a node then populate t0 & t1, and the node. More...
__hostdev__ const RayT & | ray () const
__hostdev__ RayT & | ray ()

## Detailed Description

template<typename AccT, typename RayT, typename CoordT = Coord>
class nanovdb::PointTreeMarcher< AccT, RayT, CoordT >

A Tree Marcher for Point Grids.

Note
  This class will handle correctly offseting the ray by 0.5 to ensure that the underlying HDDA will intersect with the grid-cells. See details below.

## Member Typedef Documentation

## ◆ ChildT

using ChildT = typename NodeT::ChildNodeType
| inherited

## ◆ CoordType

using CoordType = Coord
| inherited

## ◆ RealT

using RealT = RealType
| inherited

## ◆ RealType

using RealType = typename RayT::RealType
| inherited

## Constructor & Destructor Documentation

## ◆ PointTreeMarcher()

__hostdev__ PointTreeMarcher | ( | AccT & | acc | ) |
| inline

## Member Function Documentation

## ◆ init() [1/2]

__hostdev__ bool init | ( | const RayT & | indexRay | ) |
| inlineinherited

Initialize the TreeMarcher with an index-space ray.

## ◆ init() [2/2]

__hostdev__ bool init | ( | RayT | ray | ) |
| inline

Initiates this instance with a ray in index space.

An offset by 0.5 is applied to the ray to account for the fact that points in vdb grids are bucketed into so-called grid cell, which are centered round grid voxels, whereas the DDA is based on so-called grid nodes, which are coincident with grid voxels. So, rather than offsettting the points by 0.5 to bring them into a grid node representation this method offsets the eye of the ray by 0.5, which effectively ensures that the DDA operates on grid cells as oppose to grid nodes. This subtle but important offset by 0.5 is explined in more details in our online documentation.

## ◆ ray() [1/2]

__hostdev__ RayT & ray | ( |  | ) |
| inlineinherited

## ◆ ray() [2/2]

__hostdev__ const RayT & ray | ( |  | ) | const
| inlineinherited

## ◆ step()

__hostdev__ bool step | ( | const LeafNode< AccT::ValueType > ** | node,
|  | float & | t0,
|  | float & | t1
| ) |  |
| inlineinherited

step the ray through the tree. If the ray hits a node then populate t0 & t1, and the node.

Returns
  true when a node of type NodeT is intersected, false otherwise.