[Bug] saveAsImage with pixelRatio > 1 renders 3D / echarts-gl components blank

[dmunish]

Version

6.1.0

Link to Minimal Reproduction

https://codepen.io/Danish-Munib/pen/raWzBYG

Steps to Reproduce

1. Create a 3D chart using echarts-gl (e.g., line3D, surface, or bar3D).
2. Add the toolbox.feature.saveAsImage configuration.
3. Set pixelRatio in saveAsImage to a value greater than 1 (e.g., pixelRatio: 2).
4. Trigger saveAsImage via the toolbox button or programmatically using chart.getDataURL().

Current Behavior

When pixelRatio is set to 1, the exported image renders correctly.

However, setting pixelRatio > 1 results in an exported image where the WebGL viewport/3D canvas content is entirely blank. Only 2d elements (such as the visualMap legend) are rendered.

Expected Behavior

The exported image should render the complete 3D chart at high resolution corresponding to the specified pixelRatio.

Environment

- OS: Windows 10 Pro 22H2
- Browser: Brave 1.92.140 (Official Build)
- Framework: Vanilla JS

Any additional comments?

The issue appears to stem from how WebGL framebuffers handle resizing during off-screen rendering when target pixel ratios are increased.

[plainheart]

It is likely a regression in v6.1.0. I tested that it worked in v6.0.0 with echarts-gl v2.0.8.

[DaZuiZui]

Correction: my earlier version attribution was inaccurate. I initially treated this as an ECharts 6.1.0 regression, but that comparison changed both ECharts and echarts-gl versions, so it did not isolate ECharts 6.1.0 as the cause.

The failing behavior is more likely caused by the high-pixel-ratio export path in zrender, where non-builtin layers such as echarts-gl LayerGL are omitted. The proposed upstream fix is ecomfe/zrender#1164.

Sorry for the earlier misclassification.