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.TH "rtcInitPointQueryContext" "3" "" "" "Embree Ray Tracing Kernels 4"
.hy
.SS NAME
.IP
.nf
\f[C]
rtcInitPointQueryContext - initializes the context information (e.g.
  stack of (multilevel-)instance transformations) for point queries
\f[R]
.fi
.SS SYNOPSIS
.IP
.nf
\f[C]
#include <embree4/rtcore.h>

struct RTC_ALIGN(16) RTCPointQueryContext
{
  // accumulated 4x4 column major matrices from world to instance space.
  float world2inst[RTC_MAX_INSTANCE_LEVEL_COUNT][16];
  
  // accumulated 4x4 column major matrices from instance to world space.
  float inst2world[RTC_MAX_INSTANCE_LEVEL_COUNT][16];

  // instance ids.
  unsigned int instID[RTC_MAX_INSTANCE_LEVEL_COUNT];
  
  // number of instances currently on the stack.
  unsigned int instStackSize;
};

void rtcInitPointQueryContext(
  struct RTCPointQueryContext* context
);
\f[R]
.fi
.SS DESCRIPTION
.PP
A stack (\f[C]RTCPointQueryContext\f[R] type) which stores the IDs and
instance transformations during a BVH traversal for a point query.
The transformations are assumed to be affine transformations (3\[tmu]3
matrix plus translation) and therefore the last column is ignored (see
[RTC_GEOMETRY_TYPE_INSTANCE] for details).
.PP
The \f[C]rtcInitPointContext\f[R] function initializes the context to
default values and should be called for initialization.
.PP
The context will be passed as an argument to the point query callback
function (see [rtcSetGeometryPointQueryFunction]) and should be used to
pass instance information down the instancing chain for user defined
instancing (see tutorial [ClosestPoint] for a reference implementation
of point queries with user defined instancing).
.PP
The context is an necessary argument to [rtcPointQuery] and Embree
internally uses the topmost instance transformation of the stack to
transform the point query into instance space.
.SS EXIT STATUS
.PP
No error code is set by this function.
.SS SEE ALSO
.PP
[rtcPointQuery], [rtcSetGeometryPointQueryFunction]