RTCSETGEOMETRYTRANSFORMQUATERNION(3)

💅 NAME

rtcSetGeometryTransformQuaternion — bestie, this one sets the transformation for a particular time step of an instance geometry, and it does it as a decomposition of the transformation matrix using quaternions to represent the rotation. Yes, that's a lot of words. We'll get through it together 🫶

This page lives in section 3 of the Embree Ray Tracing Kernels 4 manuals, and the title is that long boi up there, rtcSetGeo...Quaternion — the man page system truncated it because even it got tired 💀

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✨ SYNOPSIS ✨

#include <embree4/rtcore.h>

void rtcSetGeometryTransformQuaternion(
  RTCGeometry geometry,
  unsigned int timeStep,
  const struct RTCQuaternionDecomposition* qd
);

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🌸 DESCRIPTION 🌸

Okay so. The rtcSetGeometryTransformQuaternion function sets the local-to-world affine transformation — that's the qd parameter, queen — of an instance geometry (that's the geometry parameter) for a particular time step (that's the timeStep parameter, we love a themed naming scheme 👑).

And the transformation is specified as an [RTCQuaternionDecomposition], which is, quote unquote, a decomposition of an affine transformation that represents the rotational component of an affine transformation as a quaternion. Why do we care? Because this lets you interpolate rotational transformations exactly using spherical linear interpolation — like a turning wheel 🎡✨, which honestly ate.

Want the full lore on the decomposition? Go read up on [RTCQuaternionDecomposition]. And heads up: the quaternion you put in the RTCQuaternionDecomposition struct will be normalized internally 🧚 so don't stress about pre-normalizing it yourself.

⚠️ Okay bestie, this is the important one, no cap: for correct results, the transformation matrices for all time steps must be set either using rtcSetGeometryTransform or rtcSetGeometryTransformQuaternion. Mixing both representations is not allowed. Pick a lane, we don't do situationships here 💀

And also: spherical linear interpolation will be used iff the transformation matrices are set with rtcSetGeometryTransformQuaternion. Iff means if-and-only-if. Iconic logic, periodt.

For an example of this whole feature in action, go check out the tutorial [Quaternion Motion Blur] 🌈

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😭 EXIT STATUS 😭

On failure, an error code is set — and you can go query it with rtcGetDeviceError 🕵️♀️

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👀 SEE ALSO 👀

• [rtcInitQuaternionDecomposition]
• [rtcSetGeometryTransform]

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Anyway, that's the whole page, mwah 💖 this one came out of the Embree Ray Tracing Kernels 4 manuals, section 3, and if you need to cite it, it's the rtcSetGeo...Quaternion(3) page. Go set some quaternions, you're gonna slay 🦋✨