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
23                #if RTC_MAX_INSTANCE_LEVEL_COUNT > 1
24                  unsigned int instStackSize;
25                #endif
26
27                unsigned int instID[RTC_MAX_INSTANCE_LEVEL_COUNT];
28
29                #if RTC_MIN_WIDTH
30                  float minWidthDistanceFactor;
31                #endif
32              };
33
34              void rtcInitIntersectContext(
35                struct RTCIntersectContext* context
36              );
37
38   DESCRIPTION
39       A per ray-query intersection context (RTCIntersectContext type) is sup‐
40       ported that can be used to configure intersection flags (flags member),
41       specify  a  filter callback function (filter member), specify the chain
42       of IDs of the current instance (instID and instStackSize members),  and
43       to attach arbitrary data to the query (e.g. per ray data).
44
45       The rtcInitIntersectContext function initializes the context to default
46       values and should be called to initialize every  intersection  context.
47       This  function  gets  inlined,  which minimizes overhead and allows for
48       compiler optimizations.
49
50       The intersection context flag can be used to tune the behavior  of  the
51       traversal  algorithm.   Using the RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT
52       flags uses an optimized traversal algorithm for  incoherent  rays  (de‐
53       fault),  while  RTC_INTERSECT_CONTEXT_FLAG_COHERENT  uses  an optimized
54       traversal algorithm for coherent rays (e.g. primary camera rays).
55
56       Best primary ray performance can be obtained by using  the  ray  stream
57       API  and  setting  the  intersect  context  flag  to RTC_INTERSECT_CON‐
58       TEXT_FLAG_COHERENT.  For secondary rays, it is typically better to  use
59       the  RTC_INTERSECT_CONTEXT_FLAG_INCOHERENT  flag,  unless  the rays are
60       known to be very coherent too (e.g. for primary transparency rays).
61
62       A filter function can be specified inside  the  context.   This  filter
63       function is invoked as a second filter stage after the per-geometry in‐
64       tersect or occluded filter function is invoked.  Only rays that  passed
65       the  first  filter stage are valid in this second filter stage.  Having
66       such a per ray-query filter function can be useful to implement modifi‐
67       cations  of  the  behavior of the query, such as collecting all hits or
68       accumulating transparencies.  The support for the context filter  func‐
69       tion  must  be  enabled  for  a  scene by using the RTC_SCENE_FLAG_CON‐
70       TEXT_FILTER_FUNCTION scene flag.  In case of  instancing  this  feature
71       has to get enabled also for each instantiated scene.
72
73       The  minWidthDistanceFactor value controls the target size of the curve
74       radii when the min-width feature is enabled.  Please see the [rtcSetGe‐
75       ometryMaxRadiusScale]  function  for more details on the min-width fea‐
76       ture.
77
78       It is guaranteed that the pointer to the intersection context passed to
79       a  ray  query  is directly passed to the registered callback functions.
80       This way it is possible to attach arbitrary data to the end of the  in‐
81       tersection context, such as a per-ray payload.
82
83       Please  note that the ray pointer is not guaranteed to be passed to the
84       callback functions, thus reading additional data from the  ray  pointer
85       passed to callbacks is not possible.
86
87   EXIT STATUS
88       No error code is set by this function.
89
90   SEE ALSO
91       [rtcIntersect1], [rtcOccluded1]
92
93
94
95                                                    rtcInitIntersectContext(3)