3D View: WebGL feedback loop - basemap texture not rendered on terrain

[linewalberglarsen]

Environment:

• qwc2-demo-app: master + 2026-lts branch
• @sourcepole/qwc-giro3d: 0.44.0-dev
• Browser: Chrome + Firefox (same issue)

Error:
"Texture level 0 would be read by TEXTURE_2D unit 0, but written
by framebuffer attachment COLOR_ATTACHMENT0, which would be illegal feedback"

Result: Terrain geometry renders correctly (white rectangle visible),
but no basemap texture is applied.

[manisandro]

You can try updating to the latest qwc master branch release, which updates various 3D libraries.

[linewalberglarsen]

Hi,

Thank you for the suggestion to try the latest qwc2 master branch release.

I updated to qwc2@2026.4.23 which now uses @giro3d/giro3d@2.0.1 instead of @sourcepole/qwc-giro3d. However, I'm now getting a new error in the browser console:

Error:
THREE.Controls: connect() now requires an element.

Environment:

• qwc2: 2026.4.23
• @giro3d/giro3d: 2.0.1
• three: 0.180.0 (required by @giro3d/giro3d@2.0.1)
• Browser: Chrome + Firefox (same issue)

Result:
The WebGL feedback loop error is gone (great progress!), but the 3D terrain still renders without any basemap texture. The THREE.Controls.connect() error appears immediately when opening 3D View.

I also had to manually remove the webpack alias "@giro3d/giro3d": "@sourcepole/qwc-giro3d" from webpack.config.js in qwc2-demo-app to get the build to succeed, as it was still aliasing to the old private fork which is no longer installed.

Could you confirm whether qwc2@2026.4.23 + @giro3d/giro3d@2.0.1 + three@0.180.0 is a tested combination, and if there is a known fix for the connect() issue?

Thank you!

[manisandro]

The THREE.Controls: connect() now requires an element. is merely a deprecation warning, right?

It is correct that you have to remove the alias.

The dependencies currently listed in the yarn.lock should always reflect the current tested combination.

[linewalberglarsen]

Hi,

Great news — the 3D basemap is now working! Here's what resolved the issue:

1. Updated qwc2 to latest (2026.4.23), which switched from @sourcepole/qwc-giro3d to @giro3d/giro3d@2.0.1. This fixed the WebGL feedback loop error.

2. Removed the webpack alias "@giro3d/giro3d": "@sourcepole/qwc-giro3d" from webpack.config.js — this was required to get the build to succeed, as the old alias was still pointing to the removed private fork.

3. Used yarn install instead of npm install to respect the yarn.lock and get the exact tested dependency combination, as suggested.

4. Switched basemap type from osm to wms in themesConfig.json, since osm and xyz types are not supported by WMSLayer3D / WMTSLayer3D in giro3d. We proxied an external OSM WMS through our own nginx to avoid CORS issues.

A few remaining notes:

• THREE.Controls: connect() now requires an element — confirmed as a deprecation warning only, not blocking.
• WMTS basemaps still crash with fromOLExtent null — not tested further since WMS works.

Thank you for the guidance — much appreciated!