---
name: "rtcInitPointQueryInstanceStack"
section: "3"
platform: "linux"
package: "libembree-dev"
version: "3.12.1+dfsg-1"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/rtcInitPointQueryInstanceStack"
---

# rtcInitPointQueryInstanceStack(3)

### NAME

-

  ```
  rtcInitPointQueryInstanceStack - initializes the stack of (multilevel-)instance
    information for point queries
  ```

### SYNOPSIS

-

  ```
  #include <embree3/rtcore.h>
  struct RTC_ALIGN(16) RTCPointQueryInstanceStack
  {
    // accumulated 4x4 column major matrices from world to instance space.
    float world2inst[RTC_MAX_INSTANCE_LEVEL_COUNT][16];

    // accumulated 4x4 column major matrices from instance to world space.
    float inst2world[RTC_MAX_INSTANCE_LEVEL_COUNT][16];
    // instance ids.
    unsigned int instID[RTC_MAX_INSTANCE_LEVEL_COUNT];

    // number of instances currently on the stack.
    unsigned int size;
  };
  void rtcInitPointQueryInstanceStack(
    struct RTCPointQueryInstanceStack* instStack
  );
  ```

### DESCRIPTION

A stack (`RTCPointQueryInstanceStack` type) which stores the IDs and instance transformations during a BVH traversal for a point query.

The `rtcInitPointQueryStack` function initializes the stack to default values and should be called for initialization.

The stack will be passed as an argument to the point query callback function (see \[rtcSetGeometryPointQueryFunction\]) and should be used to pass instance information down the instancing chain for user defined instancing (see tutorial \[ClosestPoint\] for a reference implementation of point queries with user defined instancing).

The stack is an necessary argument to \[rtcPointQuery\] and Embree internally uses the topmost instance tranformation of the stack to transform the point query into instance space.

### EXIT STATUS

No error code is set by this function.

### SEE ALSO

\[rtcPointQuery\], \[rtcSetGeometryPointQueryFunction\]