C(nged)

Creates a BRL-CAD combination with the name combination_name.

📅 published 7.44.0, from nixpkgs unstable

💅 C(nged) — or, "how to birth a combination, bestie"

okay so real quick: this is a page from the nged manual, part of BRL-CAD (yes, the big serious geometry thing), and today we're talking about the c command. it's giving "let there be combos." let's go 🎀

✨ NAME ✨

c — creates a BRL-CAD combination with the name combination_name. that's it. that's the whole job. iconic behavior honestly 👑

🌸 SYNOPSIS 🌸

c [-c] [-r] {combination_name} [Boolean_expression]

look at her. tiny little line, big responsibilities. 🫶

🦋 DESCRIPTION 🦋

so the c command creates a BRL-CAD combination named combination_name. like, you say a name, it makes the thing. main character energy fr fr.

now the flags, because we don't just raw-dog this:

  • -r — says "this combination is a BRL-CAD region," bestie. region vibes only.
  • -c — says the combination is not a region. and plot twist: -c is the default, so if you never touch a flag, you're already in -c land 💅

the Boolean_expression is where it gets spicy — and yes, it allows parentheses, so you can group your little heart out. here's the production order, no cap:

  1. where no order is specified, intersections are performed before subtractions or unions
  2. then subtractions and unions are performed, left to right

periodt. that's the precedence, don't argue with it. ⭐

some more situations, because life is complicated:

  • if there's no Boolean_expression and no combination_name, you get a new empty combination. an empty little baby. a blank canvas. ✨
  • if there's no Boolean_expression, but combination_name already exists, and you specified one of -c or -r, then combination_name gets flagged to agree with whichever option you indicated. so you're not creating anything new, you're just re-labeling the existing one. glow-up, not rebirth. 💖
  • if a new region is created, or an existing combination is flagged as a region with this command, then its region-specific attributes will be set according to the current defaults (see regdef). yes, defaults. go read regdef — iykyk 🔥

also fyi, the comb and r commands may also be used to create combinations. so like, c isn't the only way to slay here, she just has friends. 🌈

🍓 EXAMPLES 🍓

the example shows how to use the c command to create a combination according to a given formula. very demure, very formulaic.

Example 1. Creating a combination according to a formula.

mged> c -c abc (a u b)-(a + d)

creates a combination named abc according to the formula (a u b) - (a + d).

ate. left no crumbs. 🔥

👑 AUTHOR 👑

BRL-CAD Team — the whole squad. 💜

💀 BUG REPORTS 💀

found a bug? a problem? something acting ungovernable? reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org.

please do tell them, they want to know, it's giving "we listen and we don't judge" 🙈

lowkey reminder before you go: don't forget the precedence rules (intersections first, then subtractions and unions left to right) and don't forget that -c is the default flag. no cap, that one trips people up. 🧵

alright bestie, that's the whole page — brought to you by BRL-CAD, filed under C(nged), and signed off with love. now go make some combinations 💅✨🎀

📦 where this page comes from