Increase RaceApp heap size / Multiplayer graphics quality

[SuperSamus]

Combining two things into one because they are related.

In the multiplayer mode of Double Dash, the game reduces the graphics quality for performance and memory reasons. While necessary on console, I prefer playing on emulator, and I reject being bound by arbitrary limitations.

So, I made a cheat code for the PAL version to restore (almost) everything:

$Multiplayer full detail
041895A4 4E800020 # RaceMgr::getProcLevel: Force best procLevel
041CE90C 48000008 # loadCourseTask: force single-player track
0418B750 48000030 # setRace: force best LOD and mIsTinyProcess to false
041F87AC 60000000 # GeoTree: force animation
04186AB8 38000001 # RaceMgr: TexLODControl bias
041FB2B4 38000001 # Item box animTbl
041FB33C 38000001 # Item box sizeAnimTbl
041FB6D4 38000001 # Item box bmdName
041FC990 38000001 # Double item box bmdFileName
041FCA24 38000001 # Double item box animTable
041FCAB8 38000001 # Double item box sizeAnimTable
041CD8B8 60000000 # RaceApp::calc: never set 30 FPS in LAN

(Needless to say, if playing in LAN, every player needs to have to code enabled to avoid desyncs.)

Unused lines

04207E6C 38000001 # ItemObjMgr: force use shadow model data

Unfortunately, this only works on player 1. Also, on 3P/4P, shadows add to each other instead of oring (dunno what controls it), which makes the character shadow look horrible.

0424DAC4 48000008

It looks like something that controls quality? Maybe? I'm not adding if I don't know what it is. (The decomp doesn't cover this yet.)

However, basically only due to the first line, using only this code may crash the game when loading a track (depending on the number of players, track, and game mode).
_{Yes, some tracks crash the game in Grand Prix but not in VS Race (with bots forced), even with everything else being the same: Luigi Circuit (non-50cc) and Yoshi's Circuit in 2 players are an example. It appears that the difference in memory usage is caused by the result screen of all things.}

But this can be fixed by increasing the RaceApp heap:

$Increase RaceApp heap
041CCE3C 3C800065 # RaceApp: ~300 extra KiB (original `3C800060`) for the heap (tested loading all tracks with 4 players in VS with bots forced)

So...

It might seem that increasing the RaceApp heap would require enabling the extended memory in MKDD Extender, but... it's not needed? Up to 3C800071, there's no crash on load. I don't know if the game is actually leaving unused RAM by default, or what I'm doing without memory extension may cause problems...

If extending the memory was needed, I would be saying: "MKDD Extender should definitely increase that heap's size when enabling the extended memory, and have a checkbox to force the full graphics quality in multiplayer", but since this is not the case, whether this "belongs" in MKDD Extender is a bit muddy.
Though I suppose that on heavy custom tracks, a heap of size 0x710000 may not be enough.

I don't really have a conclusion for this (kinda) feature request, aside from... thoughts?

_{For reference, conversation on Discord.}

[cristian64]

This somewhat relates to some ideas I had for extending other memory heaps in the game. One of the problems at the moment is that, if the game is built to use extended simulator memory but the emulator is not configured properly, the game fails to launch with no warning.

A solution to this problem would be to make Dolphin detect that a given game requires extra simulated memory, and extend it dynamically/automatically. I made these changes in Dolphin in my local build, but I still am to open PRs, which may or may not be accepted by the Dolphin team.

I have already made the necessary changes in the Dolphin Memory Engine to detect the memory size in the running game automatically, paving the road for when Dolphin will adjust memory size dynamically: aldelaro5/dolphin-memory-engine#264.

With regards to MKDD Extender, I think it's sensible to introduce options to extend some of these memory arenas. Currently, only the memory arena that holds the unpacked preview images is extended, but I have experimented with extending the memory arena that holds character data as well, which is another one that people find limiting. With the extra 40 MiB that can be achieved in the emulator (from 24 MiB to 64 MiB), we should be able to extend safely quite a few memory heaps (e.g. for preview images, for heavier characters, for the in race app), and not only by 300 KiB, but by a few MiB each.

So, slow progress, but some progress is being made towards more available memory in MKDD when running in the emulator.

[cristian64]

I have now opened the PR for Dolphin: dolphin-emu/dolphin#14665

It will still need a round of discussions and code review, but at least the ball is moving now!

[cristian64]

dolphin-emu/dolphin#14665 was merged yesterday. If nothing goes wrong, the next Dolphin release should respect the simulated memory size that is set in the game's header in the bi2.bin file. This will allow MKDD Extender to use the extra 40 MiB that will now be up for grabs [without the user having to do any special setup in Dolphin side].

The most immediate question is how to distribute that extra resources between the various apps that coexist at one time in memory. For instance, the SequenceApp and the RaceApp do not coexist in memory, so they both could use the extra 40 MiB. On the other hand, they both coexist with the arena that unpacks MRAM.arc early after the game boots up. So, if we also want to allow for heavier karts/characters models, there needs to be some sensible balance.