---
name: "RTC_GEOMETRY_TYPE_USER"
section: "3embree4"
platform: "linux"
package: "embree"
version: "4.4.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/RTC_GEOMETRY_TYPE_USER/3embree4"
---

# RTC\_GEOMETRY\_TYPE\_USER(3embree4)

### NAME

-

  ```
  RTC_GEOMETRY_TYPE_USER - user geometry type
  ```

### SYNOPSIS

-

  ```
  #include <embree4/rtcore.h>
  RTCGeometry geometry =
    rtcNewGeometry(device, RTC_GEOMETRY_TYPE_USER);
  ```

### DESCRIPTION

User-defined geometries contain a number of user-defined primitives, just like triangle meshes contain multiple triangles. The shape of the user-defined primitives is specified through registered callback functions, which enable extending Embree with arbitrary types of primitives.

User-defined geometries are created by passing `RTC_GEOMETRY_TYPE_USER` to the `rtcNewGeometry` function call. One has to set the number of primitives (see `rtcSetGeometryUserPrimitiveCount`), a user data pointer (see `rtcSetGeometryUserData`), a bounding function closure (see `rtcSetGeometryBoundsFunction`), as well as user-defined intersect (see `rtcSetGeometryIntersectFunction`) and occluded (see `rtcSetGeometryOccludedFunction`) callback functions. The bounding function is used to query the bounds of all time steps of a user primitive, while the intersect and occluded callback functions are called to intersect the primitive with a ray. The user data pointer is passed to each callback invocation and can be used to point to the application’s representation of the user geometry.

The creation of a user geometry typically looks the following:

-

  ```
  RTCGeometry geometry = rtcNewGeometry(device, RTC_GEOMETRY_TYPE_USER);
  rtcSetGeometryUserPrimitiveCount(geometry, numPrimitives);
  rtcSetGeometryUserData(geometry, userGeometryRepresentation);
  rtcSetGeometryBoundsFunction(geometry, boundsFunction);
  rtcSetGeometryIntersectFunction(geometry, intersectFunction);
  rtcSetGeometryOccludedFunction(geometry, occludedFunction);
  ```

Please have a look at the `rtcSetGeometryBoundsFunction`, `rtcSetGeometryIntersectFunction`, and `rtcSetGeometryOccludedFunction` functions on the implementation of the callback functions.

Primitives of a user geometry are ignored during rendering when their bounds are empty, thus bounds have lower\>upper in at least one dimension.

See tutorial \[User Geometry\] for an example of how to use the user-defined geometries.

### EXIT STATUS

On failure `NULL` is returned and an error code is set that can be queried using `rtcGetDeviceError`.

### SEE ALSO

\[rtcNewGeometry\], \[rtcSetGeometryUserPrimitiveCount\], \[rtcSetGeometryUserData\], \[rtcSetGeometryBoundsFunction\], \[rtcSetGeometryIntersectFunction\], \[rtcSetGeometryOccludedFunction\]