Manpages - rtcSetGeometryOccludedFunction.3embree3

  rtcSetGeometryOccludedFunction - sets the callback function to
    test a user geometry for occlusion

  #include <embree3/rtcore.h>

  struct RTCOccludedFunctionNArguments
  {
    int* valid;
    void* geometryUserPtr;
    unsigned int primID;
    struct RTCIntersectContext* context;
    struct RTCRayN* ray;
    unsigned int N;
    unsigned int geomID;
  };

  typedef void (*RTCOccludedFunctionN)(
    const struct RTCOccludedFunctionNArguments* args
  );

  void rtcSetGeometryOccludedFunction(
    RTCGeometry geometry,
    RTCOccludedFunctionN filter
  );

The rtcSetGeometryOccludedFunction function registers a ray/primitive occlusion callback function (filter argument) for the specified user geometry (geometry argument).

Only a single callback function can be registered per geometry, and further invocations overwrite the previously set callback function. Passing NULL as function pointer disables the registered callback function.

The registered callback function is invoked by rtcOccluded-type ray queries to test whether the rays of a packet of variable size are occluded by a user-defined primitive. The callback function of type RTCOccludedFunctionN gets passed a number of arguments through the RTCOccludedFunctionNArguments structure. The value N specifies the ray packet size, valid points to an array of integers which specify whether the corresponding ray is valid (-1) or invalid (0), the geometryUserPtr member points to the geometry user data previously set through rtcSetGeometryUserData, the context member points to the intersection context passed to the ray query, the ray member points to a ray packet of variable size N, and the geomID and primID member identifies the geometry ID and primitive ID of the primitive to intersect.

The task of the callback function is to intersect each active ray from the ray packet with the specified user primitive. If the user-defined primitive is missed by a ray of the ray packet, the function should return without modifying the ray. If an intersection of the user-defined primitive with the ray was found in the valid range (from tnear to tfar), it should set the tfar member of the ray to -inf.

As a primitive might have multiple intersections with a ray, the occlusion filter function needs to be invoked by the user geometry occlusion callback for each encountered intersection, if filtering of intersections is desired. This can be achieved through the rtcFilterOcclusion call.

Within the user geometry occlusion function, it is safe to trace new rays and create new scenes and geometries.

On failure an error code is set that can be queried using rtcGetDeviceError.

[rtcSetGeometryIntersectFunction], [rtcSetGeometryUserData], [rtcFilterOcclusion]