David Haywood’s MAME(tm) WIP

Joerg Hartenberger dumped and added 2 of the remaining 3 G-Net games. Still waiting on correct metadata for them before I submit his additions, but using fake metadata they boot.

Otenami Haiken is a collection of Minigames (Card / Board games)

Shanghai Sangokuhai Tougi.. is well, Shanghai, and seems almost identical to the Naomi version I got running this morning, just in a lower resolution because its on GNet (Playstation) hardware.

Naomi / Dreamcast can store textures in various formats in RAM. Like many 3d Systems there is a format which is optimized for drawing with the graphics hardware. This is called a ‘Twiddled’ texture, and has the data arranged in a way which means the hardware can process it more efficiently. The Playstation does the same with it’s ‘Twizzled’ textures.

Kale recent came up with a fix that got Shikigami No Shiro II booting (the sequel to the recently emulated G-Net title), however, there was a problem with it. The character portraits on the select screen were corrupt. This wasn’t the first time we’d seen such corruption, Lupin The Third – The Typing suffered from a similar problem. I decided to take a look at the problem.

After a lot of searching, and false leads, it actually turned out to be something really simple. The lookup array we use for decoding Twiddled textures wasn’t being fully populated by the code, and driver was attempting to use an uninitialized entry, and things were generally appearing rather broken. A very simple fix gave fixed portraits in Shikigami and Fixed HUD graphics in Lupin.

Kale’s fix to make Shikigami II boot also allowed Under Defeat to boot, but I’ll let him put up some pictures of that if he wants to as I haven’t fixed anything in it to post about :-)

On the Dreamcast / Naomi if a texture has the ‘MipMap’ flag set, then you have to take special care when addressing the textures.

Basically MipMapping means that there are a bunch of textures of different resolutions stored in texture ram. Depending on how large the image is to appear on screen a different texture will be used. We don’t emulate MipMapping yet, but that doesn’t mean we can just ignore it.

The way the textures are stored in memory means that the lowest resolution textures are stored first. Therefore if your texture should be 512×512, there are copies at 1×1, 2×2, 4×4, 8×8, 16×16, 32×32, 64×64, 128×128 and 256×256 stored in video ram before it.

Depending on the texture mode (bpp, palettized, compressed etc.) and size of the texture, you have to apply the correct offset to get the full resolution texture. Previously we were just drawing the first one every time, which was the source of the issues seen in the Ikaruga and Border Down screenshots in the previous update. By selecting the correct texture things look much better.

Ikaruga

Border Down

as a bonus.. Radirgy now looks better

.. as does Karous (but still texture problems on the player?)

.. Choco Marker

.. and Spiker’s Battle

… and as a result, it’s a little bit slower again ;-)

Naomi progress has been rumbling on amongst the EmuDrama (which is as annoying to me as anybody else).

Probably the most significant progress is that Olivier Galibert beefed up the test renderer a little bit, I helped find a few bugs in the new code, and combined they give us some much nicer (although FAR from perfect) images.

I’ll add images to this post as the night goes on. These things run at anything between 10-20% speed, so as you can imagine, making images and testing them is somewhat time consuming, but these are 100% genuine MAME shots.

(just incase you didn’t believe me)

and some Guilty Gear XX Slash

Ikaruga has lots of texture problems still (looking at those now)

Border Down, likewise

Slashout, some less corrupt looking 3d textures

Playable speeds in MAME are quite a few years off, but just seeing these running gives me a warm feeling.