Glyphs are rendered distorted on some browser-OS-Hardware-configurations.

[anne-gropler]

See attached images. The correct glyphs are shown, but apparently the texture access results in wrong contours.

Configuration:
Windows 10 Pro 1903
Chrome: Version 78.0.3904.108 (Offizieller Build) (64-Bit)
Graphic card: NVIDIA GeForce GTX 1080

It does work fine on Firefox, Edge and ie11. I also attached the full diagnostic info for Firefox and Chrome.

webgl_diagnostic_chrome.txt
webgl_diagnostics_firefox.txt

[scheibel]

Does the rendering errors occur on newly tested machines or was the rendering correct some time ago?

[c-goldschmidt]

I believe it did work some weeks ago, but i cannot pinpoint the date/version when it broke.

[scheibel]

This behavior occurs when using Google swiftshader software rendering.

[anne-gropler]

Minimal working example for shadertoy (assign any texture to Channel0)

float utilityFunction(float t, float value) {
    return t;
}

float subFunction(float t, vec2 uv) {
    return utilityFunction(t, texture(iChannel0, uv)[0]);
}

void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
    // Normalized pixel coordinates (from 0 to 1)
    vec2 v_uv = fragCoord/iResolution.xy;

    float a = subFunction(0.5, v_uv);    
    fragColor = vec4(1.0, a, 0.0, 1.0);
}

Should render a completely orange frame, but instead renders a gradiant from red to yellow (left to right) with enforced SwiftShader.

[anne-gropler]

Bug was reported to Google:
https://issuetracker.google.com/u/1/issues/146041290

I will apply a workaround and open a PR with it.