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CesiumGS / cesium

An open-source JavaScript library for world-class 3D globes and maps :earth_americas:
https://cesium.com/cesiumjs/
Apache License 2.0
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Tapered Polylines render incorrectly on Linux + Nvidia #8101

Open likangning93 opened 5 years ago

likangning93 commented 5 years ago

Tapered polylines render differently on Linux when using Intel versus Nvidia graphics.

Intel:

Screenshot_20190822_143528

Nvidia:

Screenshot_20190822_143007

likangning93 commented 5 years ago

Nvidia WebGL report:

Screenshot_20190822_144256

emackey commented 5 years ago

Weird. It looks like the low-alpha fragment color values are not blending with the background at all. Are there other known blending issues on the same platform? Where alpha is ignored, or the blending mode doesn't get enabled somehow?

emackey commented 4 years ago

Reported by @mramato looking at SpaceBook on Linux:

issue8101-Spacebook-linux-alpha

issue8101-Spacebook-linux-alpha-zoom

The square boxes show the outlines of point primitives, which are square in nature. They are supposed to have a round shape, but this shape comes from the alpha channel, which has been ignored. The RGB values are coming through at full strength across the entire point primitive (white in the middle, green or red at the edges) but the effect of the alpha channel is nowhere to be found.

It's supposed to look more like this, taken from Windows:

issue8101-Spacebook-windows-alpha

issue8101-Spacebook-windows-alpha-zoom

emackey commented 4 years ago

Also interesting is that point primitives and tapered polylines show the same lack of alpha on the same platform. It suggests to me a deeper problem with alpha-blending on Linux+NVIDIA.