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webgl_teapot samples render at wrong resolution in Firefox
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- [X] I have provided steps to reproduce
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Browser affected
Firefox 85.0 (64-bit)
Description
Samples using the shiny webgl teapot render the teapot off-center and too big: it looks like width/height are being doubled or halved somewhere in the process so we're seeing the lower-left quadrant of the teapot render instead of the full view. I'm on a macOS machine with window.devicePixelRatio = 2 which might be causing the issue, but changing the DPR in Responsive Design Mode doesn't change the behavior. Looks fine on Chrome 88.0.4324.96 (Official Build) (x86_64) and Safari.
Steps to reproduce
Visit https://webrtc.github.io/samples/src/content/capture/canvas-pc/ https://webrtc.github.io/samples/src/content/capture/canvas-record/ or https://webrtc.github.io/samples/src/content/capture/canvas-video/ in Firefox.
Expected results
Properly sized and centered view of the shiny teapot is displayed on the canvas.
Actual results
Oversized lower-left quadrant view of the shiny teapot is displayed on the canvas.
The problem seems to be in the call to canvas.captureStream()
. Before it is called, the teapot looks (and moves around by dragging) just fine. After canvas.captureStream()
is called, the next time a frame is drawn (by dragging the mouse over the teapot) the canvas viewport suddenly breaks.
tagging @jan-ivar for triage
I think this is actually a Firefox bug, whenever captureStream() is called on a WebGL Canvas: https://bugzilla.mozilla.org/show_bug.cgi?id=1689479