Hi, https://www.shadertoy.com/view/DsSSWh only produces a black screen while it works in Chrome on the Mac.
Thanks for the report. Appears to be a regression with ANGLE Metal backend. If you know of any way to reduce the content and still get non-working rendering on Safari, that would be helpful. Same for any changes that would cause the rendering to work.
<rdar://problem/103732244>
https://bugs.chromium.org/p/angleproject/issues/detail?id=8479
Fixed in the blocking bug