HD mode 7 corruption in R-Type III

[timotheeg]

Hi there,

I tried out bsnes v116 on OSX (Catalina 10.15.7) to see how R-Type III would look like with HD mode 7 and noticed a rendering glitch.

It occurs about halfway in stage 1. See screenshot below.

My settings:

• Rom: R-Type III - The Third Lightning (U) [!].sfc (sha256: 4d6c7d6d2693d8d43bafaff7582f9a94885362dadd9ee4012bbbdce1ba10c30e)
• Size: 7x: 1680p
• Output: Scale
• HD mode 7: 960p
  • Perspective correction: yes
  • Supersampling: no
  • HD->SD mosaic: no

Expected behaviour: no glitch 😅

Do let me know whatever other info I could supply to help.

[Screwtapello]

For reference, the first level is also the first demo played in the attract mode, so you don't have to worry about being minimally good at R-Type in order to reproduce the issue. Here's a screenshot of that same section of the level, with the Fast PPU (and therefore HD Mode 7) disabled:

Ping @DerKoun, who wrote the HD Mode 7 code.

[Screwtapello]

DerKoun suggested on Discord that disabling "perspective correction" in the Enhancements section of the Settings dialog would avoid the corruption without disabling HD Mode 7 entirely. I can confirm his suggestion works as described.

[timotheeg]

disabling "perspective correction" in the Enhancements section of the Settings dialog would avoid the corruption without disabling HD Mode 7 entirely. I can confirm his suggestion works as described.

Works for me as well. Thank you! 🙏

[Zerowalker]

Oh i actually got a similar bug just recently on Secret of Mana, it happened randomly on a boss fight which utilizes HD Mode 7.
1 Time in just a short while, and it ran through those part many many times, it seemed to happen after going to one of the start menus, i couldn't reproduce it however.

I think i tried changing the "Perspective Correction" while this glitch was active and it didn't do anything,
which perhaps is expected?

If it's of any value i got have it recorded.

Thought it was an actual game glitch, but after seeing this i am more leaning towards it being a "bug".