Full-screen fill rectangle optimizations

[Thar0]

Greatly improves per-frame full-screen fill rectangle usage.

Vanilla OoT does the following on each frame:

• If there is no skybox and no solid background color
  • Fill the screen black
• If there is a solid background color
  • Fill the screen black
  • Fill the screen with the solid background color
• If there is a textured skybox
  • Fill the screen black
  • Draw the skybox
  • Fill the screen with a fog filter for the skybox, sun and moon using an XLU render mode

This has been improved to perform less full-screen fill rectangles per frame

• If there is no skybox and no solid background color
  • Fill the screen black
• If there is a solid background color
  • Fill the screen with the solid background color
• If there is a textured skybox
  • Draw the skybox (this acts as the framebuffer clear, with one caveat mentioned below) and use the G_RM_FOG_PRIM_A to do the fog filtering for the skybox, sun and moon all in one pass, massively reducing the consumed memory bandwidth

Also gates the Environment_FillScreen and Environment_DrawLensFlare screen fills with an alpha >= 8 check. The RDP blender uses the 5 most significant bits of alpha for blending, so if alpha were less than 8 it would just end up writing the same color back to the framebuffer. This makes absolutely sure this cannot occur.

There is a caveat that skyboxes with an open bottom will cause a "Hall of Mirrors" effect if the open bottom is ever on screen, since those pixels will end up retaining whatever was last in the framebuffer. It is assumed that there is no case in normal gameplay where this should happen, but maybe it's worth adding a toggle to give these skyboxes solid color bottom faces to avoid this.

I've also made some other minor changes

• Added a message at the final link step in the makefile. Without this it wasn't clear if the build was still working properly since final link takes a long time.
• Added editor.rulers to settings.json, this draws a vertical line at the 120 character limit in the editor to remind you where the formatter is going to cut things off at. I personally like it but maybe it's not for everyone, try it out.

[Yanis002]

seems to work properly, when you look at the skybox bottom this happens: https://imgur.com/a/YWUOoVJ, I assume this is the new expected behavior? also the linking message looks a bit weird Linking: -> build/hackeroot-mq/hackeroot-mq.elf, I think we might want a print version without the arrow somehow but ti's just a small detail (or alternatively you could remove the : to make it look like Linking -> build/hackeroot-mq/hackeroot-mq.elf)

otherwise looks good to me, really really nice to see these kinds of improvements, that's something I'd never been able to do on my own so thanks for this

[Thar0]

when you look at the skybox bottom this happens ... I assume this is the new expected behavior?

Yeah I mentioned this happens in the PR description. This is the only intended deviation from vanilla visuals. My assumption is that in regular gameplay this should never happen, but alternatively we could add a bottom face to skyboxes that's just a solid color to restore vanilla behavior. This would have a performance cost though, so I would suggest if we do this it should have a config option associated to it.

linking message looks a bit weird

Some other existing messages have the same kind of issue so I figure this could be left for a separate cleanup that focuses more on this. It was just bugging me that there was no message at all while building.

[sauraen]

I would strongly recommend adding a bottom face to the skyboxes before merging this. It can be black or whatever. The "nothing cleared the framebuffer" effect looks very bad IMO and could cause issues for people who are photosensitive as it alternates between two framebuffers. It is not rare to get the camera outside or partially outside the map even in vanilla, and definitely in romhacks.

One other thing: using the skybox to clear will only work if it is using a rendermode with coverage mode set to FULL (also known as ZAP), and it is set up to ignore incoming coverage (no IM_RD and some other bits). I'm pretty sure this is not how the skybox is set up in vanilla and it looks like it hasn't been changed here.

[Thar0]

Added the bottom face for skyboxes.

Skyboxes are drawn with the CLAMP mode with IM_RD disabled. Since the skybox is guaranteed to cover the entire screen, this is already sufficient to guarantee that coverage is reset for the frame.

[sauraen]

I think it might be a little more complicated than that, but if this has been tested on console or Ares and there aren't artifacts on the edges of sky tris, then it should be fine.

[Thar0]

Ah yeah I missed a key part of the explanation, here it is for the curious:

When force blending (which is the case here) the clamp mode sums old and new coverage before clamping. When IM_RD is disabled old cvg is assumed to be full (7) so the calculation is clamp(7 + c) which of course clamps to 7 for all c.