id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	blockedby	blocking	notify_on_close	platform	project
4792	Save gltf using instancing to reduce file size	Tom Goddard	Tom Goddard	"Kristen Browne tried saving a virus capsid to gltf using

open 6htx
sym #1 assembly 1
surface #2
save virus.glb

This creates an enormous 1.6 Gbyte gltf file because the 60 copies of the asymmetric unit are all copied.  Using instancing in the GLTF fie reduces the file size by a factor of 60.

Similar massive file sizes occur when simply saving atomic models since the atoms are instances that get copied.  This creates a file 100 times larger when atoms use 2000 triangles (for small numbers of displayed atoms).  At 20 triangles per atoms we expect similar file sizes because the GLTF node instances apparently take about the same number of bytes as 20 triangles.  The node instances will probably be much slower to read than the copied geometry and 100,000 nodes may overwhelm software like Blender.  So we may want to copy atom geometry for large numbers of atoms, also bonds."	enhancement	closed	moderate		Input/Output		fixed					kristen.browne@nih.gov	all	ChimeraX