Content behind <canvas/> with WebGL context is no longer transparent

Originator:mobdev
Number:rdar://37152263 Date Originated:2/2/2018
Status:Open Resolved:
Product:iOS Product Version:11.3 beta
Classification:Safari Reproducible:yes
 
Area:
Safari

Summary:
When using transparency in a WebGL canvas, then content behind is not visible on iOS 11.3

Steps to Reproduce:
Example: https://codepen.io/anon/pen/KQVpMw

Expected Results:
Half transparent black WebGL canvas, the red div element should shine through

Actual Results:
Full opaque black WebGL canvas, the red div do not shine through

Version/Build:
11.3 (15E5167f)

Configuration:
iPhone X (MQAD2ZD/A)
Safari App

Comments


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