SPHGROUP(nged)

SPHGROUP(nged) — BRL-CAD User Commands — okay bestie, let's go. 💖

---

✨ NAME ✨

SPHGROUP(nged) gives you sphgroup — create a group of all regions whose centers fall inside a sphere. No cap, it's giving spatial-search-but-make-it-a-combination energy. 💅

🌸 SYNOPSIS 🌸

sphgroup gname target_sphere.s

🎀 DESCRIPTION 🎀

okay so sphgroup creates a new combination called gname, and that combination contains all the regions in the database whose bounding-box center point lies within the bounding sphere defined by target_sphere.s. The sphere argument has to be an existing ELL or SPH primitive in the database, periodt.

Here's the tea on how it picks who gets in:

• It scans all regions in the database — that means objects flagged as regions — and computes each region's axis-aligned bounding box. 🦋
• A region is included in gname if the center of its bounding box is within or on the surface of target_sphere.s — specifically, if the distance from the bounding-box center to the sphere's center vertex is less than or equal to the sphere's radius. ⭐
• Non-region objects, hidden objects, and the sphere primitive itself are skipped. 🙈

All qualifying regions are added to gname as union (u) members with no item ID or air code set. If gname does not already exist, it is created; if it does exist, the new members are appended to it. 🫶

Note, bestie: the containment test uses the center of each region's bounding box, not all eight corners. A region whose center is outside the sphere is excluded even if part of its geometry overlaps the sphere. So yes, overlap alone does not save it — that's the documented behavior. 😭

🔥 EXAMPLES 🔥

Example 1. Group all regions centered inside a sphere primitive

mged> sphgroup cluster.c search_sphere.s

This creates the combination cluster.c containing all regions whose bounding-box centers lie within the sphere primitive search_sphere.s. The sphere search_sphere.s must already exist in the database and must be an ELL or SPH primitive. 💖

Example 2. First create the bounding sphere, then group

The page wraps this one in a lowkey cursed spot, so here's the exact text:

mged> make search_sphere.s sph mged> sphgroup nearby.c
search_sphere.s

This creates a unit sphere at the origin with make, then groups all regions centered within it into nearby.c. 🌈

👑 AUTHOR 👑

BRL-CAD Team — iconic. 🎀

🍓 BUG REPORTS 🍓

If you find bugs or problems, the page says to report them via electronic mail to devs@brlcad.org. fr fr, tell the devs. 💌

---

Cute footer sign-off: BRL-CAD made this page, the title is SPHGROUP(nged), and the footer did not give us a date — so no date invented here, bestie. 💅🫶