Hacker News Reader

Comment by teleforce | Hacker News Reader

The author did mention about fixed point was very popular for gamedev before floating point becoming popular due the increased in hardware capability, and most likely CORDIC was being used as well together with fixed point.

> In fact, before IEEE 754 became the popular standard that it is today, fixed point was used all the time (go and ask any gamedev who worked on stuff between 1980 and 2000ish and they'll tell you all about it).

View on HN

I believe that was mostly for performance reasons, not determinism, right?

Was gamedev between 1980 and 2000ish, can confirm. PS1 had no floating point unit.

This was the cause of the signature jiggly textures that were pervasive in PS1 games

This is a common misconception, but is not the case. For example, look at the Voodoo 1, 2, and 3, which also used fixed point numbers internally but did not suffer from this problem.

The real issue is that the PS1 has no subpixel precision. In other words, it will round a triangle coordinates to the nearest integers.

Likely the reason why they did this is because then you can completely avoid any division and multiplication hardware, with integer start and end coordinates line rasterization can be done completely with addition and comparisons.

Didn’t PS1 also lack perspective corrected texture mapping? That would definitely make textures wobbly. AFAIK they compensated for it simply by using as finely subdivided geometry as possible (which wasn’t very finely, really).

The folk that made Crash Bandicoot were pretty clever. They figured out that the PlayStation could render untextured, shaded triangles a lot faster than textured triangles, so they "textured" the main character with pixel-scale geometry. This in turn saved them enough memory to use a higher resolution frame buffer mode.

https://all-things-andy-gavin.com/2011/02/04/making-crash-ba...

It wasn't Pixel scale, more paint by numbers.

Reply on news.ycombinator.com