1rtcInitIntersectContext(3)Embree Ray Tracing Kernels 3rtcInitIntersectContext(3)
2
3
4
5   NAME
6              rtcInitIntersectContext - initializes the intersection context
7
8   SYNOPSIS
9              #include <embree3/rtcore.h>
10
11              enum RTCIntersectContextFlags
12              {
13                RTC_INTERSECT_CONTEXT_FLAG_NONE,
14                RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT,
15                RTC_INTERSECT_CONTEXT_FLAG_COHERENT,
16              };
17
18              struct RTCIntersectContext
19              {
20                enum RTCIntersectContextFlags flags;
21                RTCFilterFunctionN filter;
22                unsigned int instStackSize;
23                unsigned int instID[RTC_MAX_INSTANCE_LEVEL_COUNT];
24              };
25
26              void rtcInitIntersectContext(
27                struct RTCIntersectContext* context
28              );
29
30   DESCRIPTION
31       A per ray-query intersection context (RTCIntersectContext type) is sup‐
32       ported that can be used to configure intersection flags (flags member),
33       specify  a  filter callback function (filter member), specify the chain
34       of IDs of the current instance (instID and instStackSize members),  and
35       to attach arbitrary data to the query (e.g.  per ray data).
36
37       The rtcInitIntersectContext function initializes the context to default
38       values and should be called to initialize every  intersection  context.
39       This  function  gets  inlined,  which minimizes overhead and allows for
40       compiler optimizations.
41
42       The intersection context flag can be used to tune the behavior  of  the
43       traversal  algorithm.   Using the RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT
44       flags  uses  an  optimized  traversal  algorithm  for  incoherent  rays
45       (default),  while RTC_INTERSECT_CONTEXT_FLAG_COHERENT uses an optimized
46       traversal algorithm for coherent rays (e.g.  primary camera rays).
47
48       Best primary ray performance can be obtained by using  the  ray  stream
49       API  and  setting  the  intersect  context  flag  to RTC_INTERSECT_CON‐
50       TEXT_FLAG_COHERENT.  For secondary rays, it is typically better to  use
51       the  RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT  flag,  unless  the rays are
52       known to be very coherent too (e.g.  for primary transparency rays).
53
54       A filter function can be specified inside  the  context.   This  filter
55       function  is  invoked  as  a second filter stage after the per-geometry
56       intersect or occluded filter  function  is  invoked.   Only  rays  that
57       passed  the  first  filter stage are valid in this second filter stage.
58       Having such a per ray-query filter function can be useful to  implement
59       modifications of the behavior of the query, such as collecting all hits
60       or accumulating transparencies.  The support  for  the  context  filter
61       function  must  be enabled for a scene by using the RTC_SCENE_FLAG_CON‐
62       TEXT_FILTER_FUNCTION scene flag.
63
64       It is guaranteed that the pointer to the intersection context passed to
65       a  ray  query  is directly passed to the registered callback functions.
66       This way it is possible to attach arbitrary data  to  the  end  of  the
67       intersection context, such as a per-ray payload.
68
69       Please  note that the ray pointer is not guaranteed to be passed to the
70       callback functions, thus reading additional data from the  ray  pointer
71       passed to callbacks is not possible.
72
73   EXIT STATUS
74       No error code is set by this function.
75
76   SEE ALSO
77       [rtcIntersect1], [rtcOccluded1]
78
79
80
81                                                    rtcInitIntersectContext(3)