---
name: "RTC_GEOMETRY_TYPE_TRIANGLE"
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_TRIANGLE/3embree4"
---

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

### NAME

-

  ```
  RTC_GEOMETRY_TYPE_TRIANGLE - triangle geometry type
  ```

### SYNOPSIS

-

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

### DESCRIPTION

Triangle meshes are created by passing `RTC_GEOMETRY_TYPE_TRIANGLE` to the `rtcNewGeometry` function call. The triangle indices can be specified by setting an index buffer (`RTC_BUFFER_TYPE_INDEX` type) and the triangle vertices by setting a vertex buffer (`RTC_BUFFER_TYPE_VERTEX` type). See `rtcSetGeometryBuffer` and `rtcSetSharedGeometryBuffer` for more details on how to set buffers. The index buffer must contain an array of three 32-bit indices per triangle (`RTC_FORMAT_UINT3` format) and the number of primitives is inferred from the size of that buffer. The vertex buffer must contain an array of single precision `x`, `y`, `z` floating point coordinates (`RTC_FORMAT_FLOAT3` format), and the number of vertices are inferred from the size of that buffer. The vertex buffer can be at most 16 GB large.

The parametrization of a triangle uses the first vertex `p0` as base point, the vector `p1 - p0` as u-direction and the vector `p2 - p0` as v-direction. Thus vertex attributes `t0,t1,t2` can be linearly interpolated over the triangle the following way:

-

  ```
  t_uv = (1-u-v)*t0 + u*t1 + v*t2
       = t0 + u*(t1-t0) + v*(t2-t0)
  ```

A triangle whose vertices are laid out counter-clockwise has its geometry normal pointing upwards outside the front face, like illustrated in the following picture:

-

  ```

  ```

For multi-segment motion blur, the number of time steps must be first specified using the `rtcSetGeometryTimeStepCount` call. Then a vertex buffer for each time step can be set using different buffer slots, and all these buffers have to have the same stride and size.

Also see tutorial \[Triangle Geometry\] for an example of how to create triangle meshes.

### EXIT STATUS

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

### SEE ALSO

\[rtcNewGeometry\]