Support COLLADA2GLTF for better imports.

[fire]

Fixes: godotengine/godot-proposals#4885
Fixes: #51148
See godotengine/godot-proposals#2130

This also removes the Godot collada importer.

[akien-mga]

We'll need heavy testing on many types of Collada exports to see how this converter fares and make sure it's better than our ad hoc importer. But on the principle I'm all for it.

[akien-mga]

Code looks great, just a few nitpicks.

[akien-mga]

Alphabetical ordering :)

[akien-mga]

You can adapt description from the FBX one.

[akien-mga]

Suggested change

	// Collada importer.
	// Collada to glTF importer.

[akien-mga]

You can add this too to fix capitalization in the editor settings:

diff --git a/editor/editor_property_name_processor.cpp b/editor/editor_property_name_processor.cpp
index 09d2992e07..9f4ab6f1be 100644
--- a/editor/editor_property_name_processor.cpp
+++ b/editor/editor_property_name_processor.cpp
@@ -118,6 +118,7 @@ EditorPropertyNameProcessor::EditorPropertyNameProcessor() {
 	capitalize_string_remaps["bvh"] = "BVH";
 	capitalize_string_remaps["ca"] = "CA";
 	capitalize_string_remaps["cd"] = "CD";
+	capitalize_string_remaps["collada2gltf"] = "COLLADA2GLTF";
 	capitalize_string_remaps["cpu"] = "CPU";
 	capitalize_string_remaps["csg"] = "CSG";
 	capitalize_string_remaps["db"] = "dB";

[akien-mga]

Tested a few scenes with COLLADA2GLTF 2.1.5 on Linux:

• terrain.dae from Collada scene from SketchUp can not be imported properly #51148 seems to import fine

• torso.dae from Messed up animation when importing 3D scene DAE #14399 (comment) is broken. Worked OK-ish with the old importer in master (not sure about whether the original bug is/was still valid, skeleton seems off at least)

• skeleton_better.dae and skeleton_default.dae from Collada import: bones are incorrectly positioned #56242 - no visible change, skeleton broken with both importers.

• fotf_character2zy.dae from Collada importer introduces pops/hitches in animation due to interpolation bug #31005 (comment) - no visible change, skeleton broken with both importers. Can't say much about the bug there as the mesh doesn't move (neither with the direct .blend import)

• Shadow.dae from Reimporting a specific invalid Collada will crash the editor #35685 seems to import fine with the old importer (and no crash on reimport, so that bug seems fixed in current master). With the new importer, it's completely messed up.

So it's not a frank success so far, but to be fair there seems to be a lot of issues with importing animations and skeletons in general in master right now.

---

Tested with a build of COLLADA2GLTF from their master branch, not better.

For the record, diff to get it to compile with current GCC 12:

diff --git a/src/draco/core/hash_utils.h b/src/draco/core/hash_utils.h
index 0e8da60..8fa8574 100644
--- a/src/draco/core/hash_utils.h
+++ b/src/draco/core/hash_utils.h
@@ -15,6 +15,7 @@
 #ifndef DRACO_CORE_HASH_UTILS_H_
 #define DRACO_CORE_HASH_UTILS_H_
 
+#include <cstddef>
 #include <stdint.h>
 #include <functional>
 
diff --git a/src/draco/io/parser_utils.cc b/src/draco/io/parser_utils.cc
index 1aa52cc..85aed24 100644
--- a/src/draco/io/parser_utils.cc
+++ b/src/draco/io/parser_utils.cc
@@ -18,6 +18,7 @@
 #include <cctype>
 #include <cmath>
 #include <iterator>
+#include <limits>
 
 namespace draco {
 namespace parser {

to apply in the GLTF/dependencies/draco submodule.

Overall that library hasn't seen much activity since 2018 and seems more or less abandoned now. Might not be the best option.

We should see if we find another better converter, or get in touch with the lib maintainers and see what their plan is.

[fire]

I don't think this was a success. The work is salvageable. The importer has a self contained system that can import using anything that can take the input, output and binary flags.

In the proposal thread sketchup mentioned gltf.