RTC_GEOMETRY_TYPE_TRIANGLE(3) Embree Ray Tracing Kernels 3 RTC_GEOMETRY_TYPE_TRIANGLE(3)

## NAME¶

```RTC_GEOMETRY_TYPE_TRIANGLE - triangle geometry type
```

## SYNOPSIS¶

```#include <embree3/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.