table of contents
|rtcIntersect1(3)||Embree Ray Tracing Kernels 3||rtcIntersect1(3)|
rtcIntersect1 - finds the closest hit for a single ray
#include <embree3/rtcore.h> void rtcIntersect1( RTCScene scene, struct RTCIntersectContext* context, struct RTCRayHit* rayhit );
DESCRIPTION¶The rtcIntersect1 function finds the closest hit of a single ray with the scene (scene argument). The provided ray/hit structure (rayhit argument) contains the ray to intersect and some hit output fields that are filled when a hit is found.
The user has to initialize the ray origin (org ray member), ray direction (dir ray member), ray segment (tnear, tfar ray members), and set the ray flags to 0 (flags ray member). If the scene contains motion blur geometries, also the ray time (time ray member) must be initialized to a value in the range [0, 1]. If ray masks are enabled at compile time, the ray mask (mask ray member) must be initialized as well. The ray segment has to be in the range [0, ∞], thus ranges that start behind the ray origin are not valid, but ranges can reach to infinity. See Section [RTCRay] for the ray layout description.
The geometry ID (geomID hit member) of the hit data must be initialized to RTC_INVALID_GEOMETRY_ID (-1).
Further, an intersection context for the ray query function must be created and initialized (see rtcInitIntersectContext).
When no intersection is found, the ray/hit data is not updated. When an intersection is found, the hit distance is written into the tfar member of the ray and all hit data is set, such as unnormalized geometry normal in object space (Ng hit member), local hit coordinates (u, v hit member), instance ID stack (instID hit member), geometry ID (geomID hit member), and primitive ID (primID hit member). See Section [RTCHit] for the hit layout description.
If the instance ID stack has a prefix of values not equal to RTC_INVALID_GEOMETRY_ID, the instance ID on each level corresponds to the geometry ID of the hit instance of the higher-level scene, the geometry ID corresponds to the hit geometry inside the hit instanced scene, and the primitive ID corresponds to the n-th primitive of that geometry.
If level 0 of the instance ID stack is equal to RTC_INVALID_GEOMETRY_ID, the geometry ID corresponds to the hit geometry inside the top-level scene, and the primitive ID corresponds to the n-th primitive of that geometry.
The implementation makes no guarantees that primitives whose hit distance is exactly at (or very close to) tnear or tfar are hit or missed. If you want to exclude intersections at tnear just pass a slightly enlarged tnear, and if you want to include intersections at tfar pass a slightly enlarged tfar.
The ray/hit structure must be aligned to 16 bytes.