ARCED(nged)

Provides a means for directly editing transformation matrices of Boolean tree leaves.

📅 published 7.44.0, from nixpkgs unstable

✨ ARCED(nged) — the arced page, bestie edition ✨

okay so real quick, the manual name situation: this is arced from the nged section of the BRL-CAD User Commands docs. that's the whole vibe. now let's get into it 💅

🎀 NAME 🎀

arced — it's literally a way to directly edit the transformation matrices of Boolean tree leaves. that's it, that's the girlboss job description 🫶

🌸 SYNOPSIS 🌸

arced {comb/memb} {anim_command}

🦋 DESCRIPTION 🦋

so picture this: the objects in a BRL-CAD model are stored as Boolean combinations of primitive shapes and/or other combinations. these combinations live as Boolean trees, and every single leaf of the tree carries its own corresponding transformation matrix. the arced command is your direct line to editing those matrices — like, no middleman, we're going straight in there 💖

the first argument to arced must identify the combination and which member's matrix you're editing. the comb/memb argument says: member memb of combination comb is the one whose matrix we're touching. slay.

the rest of the arced command line is an animation command that gets applied to that matrix. here's the full menu of available animation commands, and yes i'm listing all of them:

  • matrix rarc <xlate|rot> matrix elements — replaces the member's matrix with the given matrix. out with the old, in with the new ✨
  • matrix lmul <xlate|rot> matrix elements — left multiplies the member's matrix by the given matrix.
  • matrix rmul <xlate|rot> matrix elements — right multiplies the member's matrix by the given matrix.
ngl, rarc vs lmul vs rmul is the whole personality of this command — replace, left multiply, right multiply. pick your fighter 🥊

🌈 EXAMPLES 🌈

Example 1. Rotate body/head 45 degrees about Z axis

mged>arced body/head matrix rot 0 0 45

this rotates member head (which lives in combination body) about the z axis through a 45° angle. iconic behavior honestly 💫

and here's the tea on how the matrix arguments work by default: the matrix commands expect a list of 16 matrix elements to define a matrix. but there are two shorthand options, and they ate:

  • the xlate option can be used along with three translation distances in the x, y, and z directions (in mm) as a shorthand notation for a matrix that is pure translation.
  • similarly, the rot option along with rotation angles (degrees) about the x, y, and z axes may be used as shorthand for a matrix that is pure rotation.

👑 AUTHOR 👑

BRL-CAD Team — the collective main characters behind all this 🫡

🙈 BUG REPORTS 🙑

if you find a bug or a problem (😭 it happens), reports should be submitted via electronic mail to devs@brlcad.org. don't be shy, they want to know fr fr 💜

and that's the page bestie 🎀 big shoutout to those BRL-CAD folks for the source material — this one's filed under ARCED(nged), so you know exactly where to find it again. mwah 💋

📦 where this page comes from