[Fabric 1.21.1] Hud batching makes transparent Spectrum item slot decorations cull item sprites via depth test

[kawaiixissa13]

minecraft version 1.21.1
fabric loader version 0.19.3
fabric api version 0.116.15+1.21.1
spectrum version 1.10.5
immediatelyfast version 1.6.11+1.21.1

i think its probably related to this commit 4f81ea0 but i could be wrong on that

item draw call with depth test overlay:

depth buffer before item draw call:

depth buffer after item draw call:

(the item sprite are at like depth 0.4725 and the gradient decorations are at like 0.47, u can see it eve naffects the ones that are just borders but it only hides one pixel so its harder 2 notice)

you can see that its happening with any of the items that draw a background gradient (SlotEffect.PULSE in spectrum's code), and i think its because of the depth test, it doesnt rly handle transparency very well. is it rly necessary to have the depth test on for this, it only saves like a few pixels of overdraw doesnt it? and its not on for the inventory

also it doesnt happen in the inventory, only in the hotbar

i think what amkes the difference bt the 2 is that AbstractContainerScreen.render does RenderSystem.disableDepthTest(); while Gui.render does RenderSystem.enableDepthTest(); and it isnt disabled in Gui.renderItemHotbar. idk why it only happens with hud batching tho maybe its like an ordering thing

[kawaiixissa13]

ok yea without hud batching the item draws first and THEN the decoration which would also avoid it i think...?

[kawaiixissa13]

ok working theory is its that it uses RenderLayer.getGui() for batchable buffer sources which has .setDepthTestState(LEQUAL_DEPTH_TEST) while RenderLayer.getGuiOverlay() has .setDepthTestState(NO_DEPTH_TEST)? and the issue with spectrum is that its mixins for drawItemInSlot dont set the depth test so we just get whatever it had before, which happens to be the LEQUAL_DEPTH_TEST one. i guess this could be fixed on either end then?

ok removing that change breaks durability bars in the hotbar which is weird. maybe the issue is acutally bc by the time we run drawItemInSlot HudBatchingBufferSource.renderingItem is unset? idk. i know the entry point for the hotbar is InGameHud.renderHotbarItem while the inventory uses HandledScreen.drawSlot

i was totally wrong the issue is just that it translates everything 200 on the z axis which means the "background" is drawing in front of the item

[RaphiMC]

Partially fixed on ImmediatelyFast's end. The other part has to be fixed in spectrum. You can download the fixed ImmediatelyFast build here: https://github.com/RaphiMC/ImmediatelyFast/actions/runs/30767679987