qt: optimize the frosted glass effect by not using second pass layering

Currently layering (second pass) is used to render the blurred source offscreen, and then apply the rest of the effects (tint, exclusion and noise) to the offscreen source when drawing the result in the interface.

This is not ideal, because layering requires allocating resources for offscreen rendering.

The most ideal solution would be to modify the fragment shader of the blur effect. But we currently do not do run time shader compilation, and MultiEffect does not accept overriding its shader effect.

At the same time, FastBlur from Qt 5 Compat is used as fallback when Qt Quick Effects is not available. In a hypothetical scenario where we could override the fragment shader, it would mean that we would need to handle these two cases differently because MultiEffect and FastBlur use different shaders.

As a workaround, I propose having an underlay filter rectangle that acts as exclusion (due to opacity) and colorization (tint), and having an overlay as the noise layer.

Request review @chub.

changed title from qt: optimize the frosted glass effect by not using layering to qt: optimize the frosted glass effect by not using second pass layering

changed the description

added 1 commit

• 9f136acf - qt: optimize the frosted glass effect by not using second pass layering

Compare with previous version

added 1 commit

• 56e562ed - qt: optimize the frosted glass effect by not using second pass layering

Compare with previous version

added 1 commit

• 988e3b76 - qt: optimize the frosted glass effect by not using second pass layering

Compare with previous version

added 1 commit

• 97f8ec29 - qt: optimize the frosted glass effect by not using second pass layering

Compare with previous version

added MRStatus::NotCompliant label

added MRStatus::Reviewable label and removed MRStatus::NotCompliant label

resolved all threads

changed milestone to %4.0

added Component::Interface: Qt label

added 1 commit

• 248862f1 - qt: use lock file in ModelRecoveryAgent to consider multiple application instances

Compare with previous version

fails on meson

modules/gui/qt/shaders/meson.build:22:15: ERROR: File FrostedGlass.frag does not exist.

before:

after:

the effect seems a bit more transparent now, maybe this should be tweaked a bit

added MRStatus::InReview label and removed MRStatus::Reviewable label

added 58 commits

• 97f8ec29...fa60a909 - 57 commits from branch videolan:master
• a551996f - qt: optimize the frosted glass effect by not using second pass layering

Compare with previous version

approved this merge request