Is there a way to convert gltf to dae?

Question

I can make gltf files with the collada to gltf converter.

But is there a way to reverse this?

Answer 1

UPDATE - October 2019 - Blender 2.80 has shipped with full glTF 2.0 import/export capability. It also has COLLADA import/export capability, so can be used to convert one to the other.

UPDATE - November 2018 rewrote answer for glTF version 2.0, which has almost completely replaced 1.0 in the time since this question was originally asked.

glTF 2.0 can be processed by a variety of tools, many of which are listed on the glTF Tools section of the official Khronos glTF README.

Older glTF 1.0

While there are numerous command-line utilities for converting to glTF, the options are much more limited going the other way, from glTF to COLLADA or anything else. One thing to understand about this is that glTF is intended to be a runtime delivery format, not an interchange format like COLLADA. glTF strives to store its internal data in as close to GPU-ready form as possible, with mesh data organized into data structures that can be used as vertex attributes, and so on. Khronos has a tagline that glTF is "the JPG of 3D" meaning that it has wide distribution to rendering engines of all kinds.

So, importing a glTF into a 3D editing package is something like loading a JPG into a paint program. You can do it, but after the import you want to avoid any unnecessary round-trips to and from the delivery format. So you would use the paint program's native save format (.psd or .xcf etc), or the 3D modeler's native save format, to keep your own editable copy of your work, and ship the exported JPG or PNG or glTF for wide distribution.

Even so, I do expect more importers to become available as time goes on. glTF version 1.0 had an internal structure that made this quite difficult (its vertex shaders would use swaths of attribute data without explicitly marking them as positions or normals, etc.) glTF 2.0 replaced those custom shaders with modern pbr pipeline assets, with clearly marked mesh position, normal, and other data, opening the door for future import tools and utilities of all kinds.