rtcGetGeo...eHalfEdge(3)

💖 rtcGetGeometryOppositeHalfEdge 💖

okay bestie, welcome to the rtcGetGeo...eHalfEdge(3) page from the Embree Ray Tracing Kernels 4 manual — yes that's the truncated title, she's mysterious like that, but we're getting into it. sit down, grab a strawberry, this one's short and sweet. 🍓

✨ NAME ✨

rtcGetGeometryOppositeHalfEdge — returns the opposite half edge 🦋

✨ SYNOPSIS ✨

#include <embree4/rtcore.h>

unsigned int rtcGetGeometryOppositeHalfEdge(
  RTCGeometry geometry,
  unsigned int topologyID,
  unsigned int edgeID
);

✨ DESCRIPTION ✨

so, the rtcGetGeometryOppositeHalfEdge function hands you back the ID of the opposite half edge of whatever half edge you point at with the edgeID argument, inside the topology you picked with the topologyID argument. no cap. 💅

for example, in the following example the opposite half edge of e6 is e16. literally iconic behavior. ✨

now here's the part where you gotta pay attention, bestie 😭 — an opposite half edge does not exist if the half edge you asked about either:

• has no neighboring face, or
• has more than 2 neighboring faces.

in those cases the function just returns the same edge edgeID right back to you. so like, it's not throwing hands, it's just handing you what you gave it. 🙈

heads up: this function can only be used for subdivision geometries. no other geometry types, periodt. 👑

and it depends on the topology, because the topologies of a subdivision geometry have different index buffers assigned. iykyk. 🌸

✨ EXIT STATUS ✨

on failure an error code is set, and you can go query it with rtcGetDeviceError. 🫶

✨ SEE ALSO ✨

• [rtcGetGeometryFirstHalfEdge]
• [rtcGetGeometryFace]
• [rtcGetGeometryOppositeHalfEdge]
• [rtcGetGeometryNextHalfEdge]
• [rtcGetGeometryPreviousHalfEdge]

and that's the whole page, bestie, we ate and left no crumbs 🎀💜 this was rtcGetGeo...eHalfEdge(3) from Embree Ray Tracing Kernels 4, dropping the exact same footer title she came in with. mwah. 💖✨