Chrome Version: 62.0.3202.89 (Official Build) (64-bit)
OS: macOS 10.13

What steps will reproduce the problem?
(1) Go to https://jsfiddle.net/greggman/qafe33bL/

What is the expected result?

There is a red square in the 2nd image

What happens instead?

There is no red square in the 2nd image or sometimes garbage

Works on Firefox


I noticed this issue because sometime in September vertexshaderart.com stopped being able to take screenshots for me when saving. It seems to be around the time as macOS 10.13 release. I tried to narrow it down but the issue is semi-intermittent. What happens is the WebGL canvas is normally 300x150 but when I take screenshot I increase it to 1200x672, re-render the scene, copy to canvas 2d, then the next render will move it back down to 300x150. If I change the copy resize to 301x151 the problem goes away or is intermittent. I've even seen garbage. If I turn off the depth test the problem also seems to go away even though I'm clearing the depth buffer and there is only 1 point being drawn.