4 ms·

Fixing a Direct3D9 bug in Far Cry (2018)

65 points by anotherhue 1y ago

boristsr 1y ago
Excellent deep dive and explanation of the process of tracking down and fixing it. Thanks for sharing it, it was a fun read. Will definitely keep this in mind next time I fire up farcry for some nostalgia!
gustavorg 1y ago
The last image of this article shows the bug supposedly solved. But it does not show the same image with the bug. The images to show the bug are from different points of view, where it is difficult to appreciate the problem as the last image does.
- saejox 1y ago
  it is a subtle bug. mostly concerning preservationists. players are likely more worried about bandits shooting at them than mountains not reflected on the water.
  - extrememacaroni 1y ago
    > bandits shooting at them through walls and from kilometers away, since this is Far Cry 1 on modern systems :P
Thev00d00 1y ago
Nowadays of course you would simply use DXVK for this. The wonders of Linux gaming spilling back over onto Windows.
perching_aix 1y ago
What is this site? This is the actual site from the actual modder: https://cookieplmonster.github.io/2018/07/07/farcry-d3d9-bug/ https://cookieplmonster.github.io/2018/07/07/farcry-d3d9-bug... This looks like a copycat site? What for?
- anotherhue 1y ago
  I was unaware of this.
- hnuser123456 1y ago
  The download links and patreon links on the copied page link to those for this person. Strange.
  - mrkramer 1y ago
    He probably has 2 domains that link to the same website.
    - danudey 1y ago
      The two domains are Github.io subdomains; if you look at the user accounts for those domains, they seem to be completely different people - actual people, with actual code, history, links, socials, etc., and living in different cities even. Definitely weird.
- EdSchouten 1y ago
  It looks like @HoussemNasri forked @CookiePLMonster's website repo: https://github.com/HoussemNasri/HoussemNasri.github.io https://github.com/HoussemNasri/HoussemNasri.github.io Maybe that person simply wanted to have a nice template to work with, but forgot to scrub all the old content?
immibis 1y ago
I expect that clip planes are invalidated by changing matrix transforms. It reads to me like the code that emulates the old clip planes is probably converting them from world space to clip space using the current transforms when the clip planes are set, then not redoing the conversion if the transforms change.
northhnbesthn 1y ago
Yeah - a lot of devs don’t know about clip planes but they have their uses and they kind of function outside of the normal pipeline.
ryao 1y ago
> Community has since found a way to fix this issue - it is possible to use WineD3D, a Direct3D to OpenGL wrapper for Windows, and then everything looks fine. However, it comes at a price – performance can be lowered by as much as 75%! That can result in unacceptable framerates even on modern PCs. Has anyone tried DXVK?
- Delk 1y ago
  The post is from 2018, so dxvk either wasn't there or was too immature. From today's point of view, the post may not be that interesting in the practical sense of running the game. But some might find the obscure feature of custom clip planes interesting, or how a change or a detail in API specs lead to a regression. If course today you'd want to use dxvk.

65 points by anotherhue 1y ago

Excellent deep dive and explanation of the process of tracking down and fixing it. Thanks for sharing it, it was a fun read. Will definitely keep this in mind next time I fire up farcry for some nostalgia!

gustavorg 1y ago

The last image of this article shows the bug supposedly solved. But it does not show the same image with the bug. The images to show the bug are from different points of view, where it is difficult to appreciate the problem as the last image does.

saejox 1y ago
it is a subtle bug. mostly concerning preservationists. players are likely more worried about bandits shooting at them than mountains not reflected on the water.
- extrememacaroni 1y ago
  > bandits shooting at them through walls and from kilometers away, since this is Far Cry 1 on modern systems :P

Thev00d00 1y ago

Nowadays of course you would simply use DXVK for this. The wonders of Linux gaming spilling back over onto Windows.

perching_aix 1y ago

What is this site? This is the actual site from the actual modder: https://cookieplmonster.github.io/2018/07/07/farcry-d3d9-bug/ https://cookieplmonster.github.io/2018/07/07/farcry-d3d9-bug... This looks like a copycat site? What for?

anotherhue 1y ago
I was unaware of this.
hnuser123456 1y ago
The download links and patreon links on the copied page link to those for this person. Strange.
- mrkramer 1y ago
  He probably has 2 domains that link to the same website.
  - danudey 1y ago
    The two domains are Github.io subdomains; if you look at the user accounts for those domains, they seem to be completely different people - actual people, with actual code, history, links, socials, etc., and living in different cities even. Definitely weird.
EdSchouten 1y ago
It looks like @HoussemNasri forked @CookiePLMonster's website repo: https://github.com/HoussemNasri/HoussemNasri.github.io https://github.com/HoussemNasri/HoussemNasri.github.io Maybe that person simply wanted to have a nice template to work with, but forgot to scrub all the old content?

immibis 1y ago

I expect that clip planes are invalidated by changing matrix transforms. It reads to me like the code that emulates the old clip planes is probably converting them from world space to clip space using the current transforms when the clip planes are set, then not redoing the conversion if the transforms change.

northhnbesthn 1y ago

Yeah - a lot of devs don’t know about clip planes but they have their uses and they kind of function outside of the normal pipeline.

ryao 1y ago

> Community has since found a way to fix this issue - it is possible to use WineD3D, a Direct3D to OpenGL wrapper for Windows, and then everything looks fine. However, it comes at a price – performance can be lowered by as much as 75%! That can result in unacceptable framerates even on modern PCs. Has anyone tried DXVK?

Delk 1y ago
The post is from 2018, so dxvk either wasn't there or was too immature. From today's point of view, the post may not be that interesting in the practical sense of running the game. But some might find the obscure feature of custom clip planes interesting, or how a change or a detail in API specs lead to a regression. If course today you'd want to use dxvk.