Rive Renderer renders transparent animations incorrectly.

[OlegBezr]

Description

Rive Renderer renders transparent animations incorrectly.

Provide a Repro

minimal iOS SwiftUI app demonstrating the issue:
https://github.com/OlegBezr/RiveTransparentBug

Source .riv/.rev file

RiveRenderer_transparency_bug.zip

Expected behavior

The animation should look the same as in Skia. With RiveRenderer there's a dark gray color in place of transparent color.

Screenshots

Skia (expected animation)

RPReplay_Final1712170003.MP4

Rive Renderer (bug)

RPReplay_Final1712170121.MP4

Device & Versions (please complete the following information)

• Devices tested: physical iPhone 14 Pro Max, simulator iPhone SE 2020
• iOS versions: 17.3.1, 17.2

Additional context

Bug first mentioned here:
#269 (comment)

[OlegBezr]

@HayesGordon, looking forward to your feedback on this. Please let me know if you need anything else to make the bug clear

[OlegBezr]

@HayesGordon, we are still experiencing issues with first app launch animation loading using Skia. Really want to switch to RiveRenderer but this issue blocks us. Please let me know if there are any updates regarding this issue or any way we could contribute more to speed up the resolution. Appreciate your work, thank you!

[HayesGordon]

Hi @OlegBezr, I'll escalate this with the rest of the team. Thanks for following up.

[simontreny]

I encounter the same issue as well (see the dark edges on the cloud on top).

I think this is related to premultiplied alpha in texture assets as it only affects bitmaps and not vectorial graphics, and only with Rive's own renderer.