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                #if RTC_MAX_INSTANCE_LEVEL_COUNT > 1
23                unsigned int instStackSize;
24                #endif
25                unsigned int instID[RTC_MAX_INSTANCE_LEVEL_COUNT];
26              };
27
28              void rtcInitIntersectContext(
29                struct RTCIntersectContext* context
30              );
31
32   DESCRIPTION
33       A per ray-query intersection context (RTCIntersectContext type) is sup‐
34       ported that can be used to configure intersection flags (flags member),
35       specify  a  filter callback function (filter member), specify the chain
36       of IDs of the current instance (instID and instStackSize members),  and
37       to attach arbitrary data to the query (e.g.  per ray data).
38
39       The rtcInitIntersectContext function initializes the context to default
40       values and should be called to initialize every  intersection  context.
41       This  function  gets  inlined,  which minimizes overhead and allows for
42       compiler optimizations.
43
44       The intersection context flag can be used to tune the behavior  of  the
45       traversal  algorithm.   Using the RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT
46       flags uses an optimized traversal algorithm for  incoherent  rays  (de‐
47       fault),  while  RTC_INTERSECT_CONTEXT_FLAG_COHERENT  uses  an optimized
48       traversal algorithm for coherent rays (e.g.  primary camera rays).
49
50       Best primary ray performance can be obtained by using  the  ray  stream
51       API  and  setting  the  intersect  context  flag  to RTC_INTERSECT_CON‐
52       TEXT_FLAG_COHERENT.  For secondary rays, it is typically better to  use
53       the  RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT  flag,  unless  the rays are
54       known to be very coherent too (e.g.  for primary transparency rays).
55
56       A filter function can be specified inside  the  context.   This  filter
57       function is invoked as a second filter stage after the per-geometry in‐
58       tersect or occluded filter function is invoked.  Only rays that  passed
59       the  first  filter stage are valid in this second filter stage.  Having
60       such a per ray-query filter function can be useful to implement modifi‐
61       cations  of  the  behavior of the query, such as collecting all hits or
62       accumulating transparencies.  The support for the context filter  func‐
63       tion  must  be  enabled  for  a  scene by using the RTC_SCENE_FLAG_CON‐
64       TEXT_FILTER_FUNCTION scene flag.
65
66       It is guaranteed that the pointer to the intersection context passed to
67       a  ray  query  is directly passed to the registered callback functions.
68       This way it is possible to attach arbitrary data to the end of the  in‐
69       tersection context, such as a per-ray payload.
70
71       Please  note that the ray pointer is not guaranteed to be passed to the
72       callback functions, thus reading additional data from the  ray  pointer
73       passed to callbacks is not possible.
74
75   EXIT STATUS
76       No error code is set by this function.
77
78   SEE ALSO
79       [rtcIntersect1], [rtcOccluded1]
80
81
82
83                                                    rtcInitIntersectContext(3)