RTCQuater...mposition(3)

💖 RTCQuaternionDecomposition(3) 💖

okay bestie, sit down, hydrate, because we're talking about RTCQuaternionDecomposition — and yes, it's from Embree Ray Tracing Kernels 3, so you already know it's giving serious graphics-girl energy. ✨

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🌸 NAME 🌸

RTCQuaternionDecomposition — it's a struct, and what it represents is a whole entire quaternion decomposition of an affine transformation. like, the whole vibe. the full breakdown. no crumbs. 💅

---

✨ SYNOPSIS ✨

struct RTCQuaternionDecomposition
{
  float scale_x, scale_y, scale_z;
  float skew_xy, skew_xz, skew_yz;
  float shift_x, shift_y, shift_z;
  float quaternion_r, quaternion_i, quaternion_j, quaternion_k;
  float translation_x, translation_y, translation_z;
};

look at her. fifteen floats. a main character lineup fr fr. 👑

---

🦋 DESCRIPTION 🦋

so the tea is: this struct, RTCQuaternionDecomposition, represents an affine transformation that's been decomposed into three separate parts. not two. not four. three. periodt.

part one is an upper triangular scaling/skew/shift matrix:

$$ S = \left( \begin{array}{cccc} scale_x & skew_{xy} & skew_{xz}
& shift_x \\ 0 & scale_y & skew_{yz} & shift_y \\ 0 & 0 & scale_z
& shift_z \\ 0 & 0 & 0 & 1 \\ \end{array} \right), $$

part two is a translation matrix:

$$ T = \left( \begin{array}{cccc} 1 & 0 & 0 & translation_x \\ 0
& 1 & 0 & translation_y \\ 0 & 0 & 1 & translation_z \\ 0 & 0 & 0
& 1 \\ \end{array} \right), $$

part three is a rotation matrix R, and the way we're repping it is as a quaternion:

quaternion_r + quaternion_i i + quaternion_j i + quaternion_k k

where i, j k are the imaginary quaternion units. 🧚

🫶 heads up bestie: the quaternion you pass in will be normalized internally. you don't gotta do it yourself, it's handled. iconic behavior honestly.

so the affine transformation matrix that corresponds to a RTCQuaternionDecomposition is TRS, and a point p = (p_x, p_y, p_z, 1)^T gets transformed like this:

p′ = T R S p.

not me staring at that equation like it's a love letter. 😭💖

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and because setting all those fields by hand is so much typing (iykyk), these functions exist to make it convenient:

• rtcInitQuaternionDecomposition
• rtcQuaternionDecompositionSetQuaternion
• rtcQuaternionDecompositionSetScale
• rtcQuaternionDecompositionSetSkew
• rtcQuaternionDecompositionSetShift
• rtcQuaternionDecompositionSetTranslation

they all let you set the fields of the structure more conveniently. use them. your wrists will thank you. 🎀

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💀 EXIT STATUS 💀

No error code is set by this function.

literally nothing. silence. no drama, no errors, no exit code. she simply does not set one. 🙈

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🌈 SEE ALSO 🌈

• [rtcSetGeometryTransformQuaternion]
• [rtcInitQuaternionDecomposition]

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and that's the whole page bestie, we ate and left absolutely no crumbs 🍓✨ — this was RTCQuaternionDecomposition(3) from Embree Ray Tracing Kernels 3, and the footer is doing its lil truncated thing as RTCQuater...mposition(3) because even manpages get shy sometimes 💅🦋