---
name: "rtcSetGeometryTopologyCount"
section: "3"
platform: "linux"
package: "libembree-dev"
version: "4.3.3+dfsg-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/rtcSetGeometryTopologyCount"
---

# rtcSetGeometryTopologyCount(3)

### NAME

-

  ```
  rtcSetGeometryTopologyCount - sets the number of topologies of
    a subdivision geometry
  ```

### SYNOPSIS

-

  ```
  #include <embree4/rtcore.h>
  void rtcSetGeometryTopologyCount(
    RTCGeometry geometry,
    unsigned int topologyCount
  );
  ```

### DESCRIPTION

The `rtcSetGeometryTopologyCount` function sets the number of topologies (`topologyCount` parameter) for the specified subdivision geometry (`geometry` parameter). The number of topologies of a subdivision geometry must be greater or equal to 1.

To use multiple topologies, first the number of topologies must be specified, then the individual topologies can be configured using `rtcSetGeometrySubdivisionMode` and by setting an index buffer (`RTC_BUFFER_TYPE_INDEX`) using the topology ID as the buffer slot.

### EXIT STATUS

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

### SEE ALSO

\[RTC\_GEOMETRY\_TYPE\_SUBDIVISION\], \[rtcSetGeometrySubdivisionMode\]