Rendering Fluids in fabulous graphics mode GUI doesn't work

[shartte]

I am using the following code to render a Fluid slot (s) in my GUI, which works perfectly in fancy or fast graphics, but is invisible in fabulous graphics.

 List<FluidRenderFace> faces = new ArrayList<>();
 faces.add(FluidRenderFace.createFlatFaceZ(0, 0, 0, 16, 16, 0, 1 / 16., false, false));

 matrices.push();
 matrices.translate(s.x, s.y, 0);

 FluidVolume fluidStack = fs.getFluidStack();
 fluidStack.render(faces, FluidVolumeRenderer.VCPS, matrices);
 FluidVolumeRenderer.VCPS.draw();
 matrices.pop();

[shartte]

I tracked it down to the following:
Translucent layers are rendered into a separate framebuffer, which is never blitted back to screen after the world itself has already been drawn (which is under the GUI).

Workaround: RenderSystem.runAsFancy(FluidVolumeRenderer.VCPS::draw);

That is deprecated though.

[AlexIIL]

That's annoying. I'll change ExpandingVcp.draw to go through RenderSystem.runAsFancy.

[shartte]

I am also not sure how to solve this going forward.
This should also affect item renderers in theory, I guess, or the fluid rendering should not actually render to the "transparent" layer for the UI.

[AlexIIL]

Do item renders have their own VCP? I know this isn't a problem for blocks, as they use the main one.

(For simplicities sake I'll expose a draw method that doesn't use runAsFancy - that way if they don't they can use that).

Drawing translucent fluids in GUIs should be fine so I'm hesitant to try to change fluid rendering just for this.

[shartte]

As long as they render into the transparent layer they will have this problem.
Root cause here is net.minecraft.client.render.RenderPhase#TRANSLUCENT_TARGET, because that will switch the render target.

Thinking about this some more: RenderLayers should really not be used when rendering for the UI I think...