rtcForwardIntersect1/Ex(3)

  NAME

    rtcForwardIntersect1/Ex - forwards a single ray to new scene
      from user geometry callback

  SYNOPSIS

    #include <embree4/rtcore.h>

    void rtcForwardIntersect1(
      const struct RTCIntersectFunctionNArguments* args,
      RTCScene scene,
      struct RTCRay* ray,
      unsigned int instID
    );

    void rtcForwardIntersect1Ex(
      const struct RTCIntersectFunctionNArguments* args,
      RTCScene scene,
      struct RTCRay* ray,
      unsigned int instID,
      unsigned int instPrimID,
    );

  DESCRIPTION

The rtcForwardIntersect1 and rtcForwardIntersect1Ex functions forward the traversal of a transformed ray (ray argument) into a scene (scene argument) from a user geometry callback. The function can only get invoked from a user geometry callback for a ray traversal initiated with the rtcIntersect1 function. The callback arguments structure of the callback invokation has to get passed to the ray forwarding (args argument). The user geometry callback should instantly terminate after invoking the rtcForwardIntersect1/Ex function.

Only the ray origin and ray direction members of the ray argument are used for forwarding, all additional ray properties are inherited from the initial ray traversal invokation of rtcIntersect1.

The implementation of the rtcForwardIntersect1 function recursively continues the ray traversal into the specified scene and pushes the provided instance ID (instID argument) to the instance ID stack. Hit information is updated into the ray hit structure passed to the original rtcIntersect1 invokation.

This function can get used to implement user defined instancing using user geometries, e.g. by transforming the ray in a special way, and/or selecting between different scenes to instantiate.

For user defined instance arrays, the rtcForwardIntersect1Ex variant has an additional instPrimID argument which is pushed to the instance primitive ID stack. Instance primitive IDs identify which instance of an instance array was hit.

When using Embree on the CPU it is possible to recursively invoke rtcIntersect1 directly from a user geometry callback. However, when SYCL is used, recursively tracing rays is not directly supported, and the rtcForwardIntersect1/Ex functions must be used.

The ray structure must be aligned to 16 bytes.

  EXIT STATUS

For performance reasons this function does not do any error checks, thus will not set any error flags on failure.

  SEE ALSO

[rtcIntersect1], [RTCRay]