gltf exporter does not export non-byte color and non-face-corner vertex colors in 3.3 alpha #99005

New Issue

Ivan Notaros · 2022-06-20T05:04:59+02:00

Ivan Notaros commented

2022-06-20 05:04:59 +02:00

Blender Version
3.3.0-alpha+master.6ad9d8e2247d-windows.amd64-release

Short description of error

Exact steps for others to reproduce the error

Create an object
Add color attribute layer (don't choose Face Corner + Byte Color) optionally paint something on it with Vertex Paint
Export as glft/glb
Make sure the Vertex Color export option is enabled in Geometry tab
gltf doesn't have vertex color

Opening the gltf you can see that the attributes are:

                    "attributes" : {
                        "POSITION" : 0,
                        "NORMAL" : 1,
                        "TEXCOORD_0" : 2
                    },

COLOR_0 is missing

test_vertex.blend
2022-07-07 10-12-27.mp4

**Blender Version** 3.3.0-alpha+master.6ad9d8e2247d-windows.amd64-release **Short description of error** **Exact steps for others to reproduce the error** 1. Create an object 2. Add color attribute layer (don't choose Face Corner + Byte Color) optionally paint something on it with Vertex Paint 3. Export as glft/glb 4. Make sure the Vertex Color export option is enabled in Geometry tab 5. gltf doesn't have vertex color Opening the gltf you can see that the attributes are: ``` "attributes" : { "POSITION" : 0, "NORMAL" : 1, "TEXCOORD_0" : 2 }, ``` COLOR_0 is missing [test_vertex.blend](https://archive.blender.org/developer/F13264690/test_vertex.blend) [2022-07-07 10-12-27.mp4](https://archive.blender.org/developer/F13264687/2022-07-07_10-12-27.mp4)

Ivan Notaros commented

2022-06-20 05:04:59 +02:00

Added subscriber: @nothke

blender-admin commented

2022-06-20 05:04:59 +02:00

#99509 was marked as duplicate of this issue

Scurest commented

2022-06-20 05:38:58 +02:00

Added subscriber: @scurest

Scurest commented

2022-06-20 05:38:58 +02:00

What kind of color attribute layer? The exporter still only supports pre-3.2 style vertex colors, ie. Face Corner + Byte Color.

Pratik Borhade commented

2022-06-20 06:43:44 +02:00

Added subscriber: @PratikPB2123

Julien Duroure commented

2022-06-20 13:51:13 +02:00

Added subscriber: @JulienDuroure

Julien Duroure commented

2022-06-20 13:51:43 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Ivan Notaros commented

2022-06-21 14:47:13 +02:00

In #99005#1376715, @scurest wrote:
What kind of color attribute layer? The exporter still only supports pre-3.2 style vertex colors, ie. Face Corner + Byte Color.

Oh, that's true, it's still possible to export only with face corner + byte color, it's not a regression then. I managed to transfer vertices to corners via Geometry Nodes and export like that.

Aaaanyway, the reason why I wanted to export vertex-based and not face-corner based color was just so vertex color bakes would look better, but it turned out that this was not the issue with color domain, but with baking and denoising.

> In #99005#1376715, @scurest wrote: > What kind of color attribute layer? The exporter still only supports pre-3.2 style vertex colors, ie. Face Corner + Byte Color. Oh, that's true, it's still possible to export only with face corner + byte color, it's not a regression then. I managed to transfer vertices to corners via Geometry Nodes and export like that. Aaaanyway, the reason why I wanted to export vertex-based and not face-corner based color was just so vertex color bakes would look better, but it turned out that this was not the issue with color domain, but with baking and denoising.

Ivan Notaros changed title from ~~Regression: gltf exporter does not export vertex colors in 3.3 alpha~~ to gltf exporter does not export non-byte color and non-face-corner vertex colors in 3.3 alpha

2022-06-21 14:48:44 +02:00

Scurest commented

2022-06-21 20:52:00 +02:00

It's technically straightforward to add support for this. Main considerations:

It's easiest to first refactor the exporter to handle generic attributes, each with their own domain/type. Vertex position etc. can be treated as a generic attribute too. This also makes it easy to add custom attribute support.
Byte colors should continue to export as unorm16x4.
Float colors should probably export as floatx4, with full precision.
If float colors are all opaque, can export as RGB floatx3 instead. (Could also do it for byte color, but it wouldn't save space because of alignment.)
Per-vertex color (unlike per-corner color) can be exported for loose point/line primitives. (Keep in mind though it's invalid to have noncontiguous n in COLOR_n.)
Since color attributes don't have a controllable sort order, it doesn't make much sense to linearize them onto COLOR_0, COLOR_1, ... anymore IMO. It makes more sense to me to export only the active attribute as COLOR_0 and not export COLOR_1 or higher at all. Cf.

It's technically straightforward to add support for this. Main considerations: - It's easiest to first refactor the exporter to handle generic attributes, each with their own domain/type. Vertex position etc. can be treated as a generic attribute too. This also makes it easy to add custom attribute support. - Byte colors should continue to export as unorm16x4. - Float colors should probably export as floatx4, with full precision. - If float colors are all opaque, can export as RGB floatx3 instead. (Could also do it for byte color, but it wouldn't save space because of alignment.) - Per-vertex color (unlike per-corner color) can be exported for loose point/line primitives. (Keep in mind though it's invalid to have noncontiguous n in COLOR_n.) - Since color attributes don't have a controllable sort order, it doesn't make much sense to linearize them onto COLOR_0, COLOR_1, ... anymore IMO. It makes more sense to me to export only the active attribute as COLOR_0 and not export COLOR_1 or higher at all. [Cf.](https://github.com/KhronosGroup/glTF-Blender-IO/pull/807#issuecomment-1143804923)

Julien Duroure self-assigned this 2022-06-25 15:50:37 +02:00

Julien Duroure commented

2022-06-25 15:50:37 +02:00

I will take care of that. Hoping for 3.3

Pratik Borhade commented

2022-07-07 05:44:42 +02:00

Added subscriber: @1029910278

Pratik Borhade commented

2022-07-07 05:44:58 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Julien Duroure commented

2022-07-07 07:52:07 +02:00

A PR is under review here:

https://github.com/KhronosGroup/glTF-Blender-IO/pull/1678

A PR is under review here: https://github.com/KhronosGroup/glTF-Blender-IO/pull/1678

Julien Duroure commented

2022-07-17 16:28:04 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Julien Duroure closed this issue

2022-07-17 16:28:04 +02:00

Julien Duroure commented

2022-07-17 16:28:04 +02:00

Fixed by 2fcac97522

Fixed by 2fcac97522de

tom k commented

2022-09-27 17:42:37 +02:00

Added subscriber: @tomjk

tom k commented

2022-09-27 17:42:37 +02:00

I'm still having an issue exporting color-type vertex colors with gltf in blender 3.3.0 official release for linux.

steps (basically same as in original post):

add object
under color attributes, click add attribute, select domain: face-corner, data type: color, press ok.
export gltf (selected only; y-up; mesh with uvs, normals, vertex colors; material with export/auto; no animation).

Vertex colors don't appear in exported file.

example for an exported plane (edited for clarity):

{
    "asset" : {
        "generator" : "Khronos glTF Blender I/O v3.3.27",
        "version" : "2.0"
    },
    "scene" : 0,
    "scenes" : [...],
    "nodes" : [...],
    "meshes" : [
        {
            "name" : "Plane.001",
            "primitives" : [
                {
                    "attributes" : {
                        "POSITION" : 0,
                        "NORMAL" : 1,
                        "TEXCOORD_0" : 2
                    },
                    "indices" : 3
                }
            ]
        }
    ],
    "accessors" : [...],
    "bufferViews" : [...],
    "buffers" : [
        {
            "byteLength" : 140,
            "uri" : "data:application/octet-stream;base64,AACAvwAAAAAAAIA/AACAPwAAAAAAAIA/AACAvwAAAAAAAIC/AACAPwAAAAAAAIC/AAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAIA/AACAPwAAAAAAAAAAAACAPwAAAAAAAAEAAwAAAAMAAgA="
        }
    ]
}

I'm still having an issue exporting color-type vertex colors with gltf in blender 3.3.0 official release for linux. steps (basically same as in original post): 1. add object 2. under color attributes, click add attribute, select domain: face-corner, data type: color, press ok. 3. export gltf (selected only; y-up; mesh with uvs, normals, vertex colors; material with export/auto; no animation). Vertex colors don't appear in exported file. example for an exported plane (edited for clarity): ``` { "asset" : { "generator" : "Khronos glTF Blender I/O v3.3.27", "version" : "2.0" }, "scene" : 0, "scenes" : [...], "nodes" : [...], "meshes" : [ { "name" : "Plane.001", "primitives" : [ { "attributes" : { "POSITION" : 0, "NORMAL" : 1, "TEXCOORD_0" : 2 }, "indices" : 3 } ] } ], "accessors" : [...], "bufferViews" : [...], "buffers" : [ { "byteLength" : 140, "uri" : "data:application/octet-stream;base64,AACAvwAAAAAAAIA/AACAPwAAAAAAAIA/AACAvwAAAAAAAIC/AACAPwAAAAAAAIC/AAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAACAAAAAAAAAgD8AAIA/AACAPwAAAAAAAAAAAACAPwAAAAAAAAEAAwAAAAMAAgA=" } ] } ```

Julien Duroure commented

2022-09-27 18:09:24 +02:00

@tomjk Confirmed. Seems there was some change in API between this fix and final release. Will check, and fix. This should be included in 3.3.x release (trying 3.3.1)