4 ms·

Older versions of Minecraft had a similar issue. The block display started to get desynchronized with large enough coordinates, because their coordinates were r

Older versions of Minecraft had a similar issue. The block display started to get desynchronized with large enough coordinates, because their coordinates were relative to the world origin and not the player/camera position and truncation errors got large enough to have visible effects. (You can see them from most Far Lands videos.) It should be noted that floating point is not really an issue for both Patriot and Minecraft. There would have been similar issues even when fixed integers of the same size, 24 and 32 bits respectively, were used. The real issue is that there were two values where one is much larger than another, and they were combined into a single variable without further consideration.

justinl33 3y ago
> The real issue is that there were two values where one is much larger than another, and they were combined into a single variable without further consideration. What do you mean by this? How is this related to the Far Lands generation?
- xeonmc 3y ago
  It's called catastrophic cancellation. Consider the following example: 999999 + 0.0000001 ~= 999999
  - justinl33 3y ago
    Why doesn't it wrap around?
    - nzentzis 3y ago
      The problem is that there aren’t enough digits of precision to represent the answer. The exact answer would be 999999.0000001, but let’s say you only have space to store six significant digits. The exact answer is way more precise, so you need to round it to the nearest representable value, 999999. Floating-point rounding issues are the same thing but with binary digits instead of decimal ones.
- lifthrasiir 3y ago
  Graphical glitches I mentioned are independent from the Far Lands---AFAIK they start to happen around 1--2 million blocks from the origin, much closer than the Far Lands (~12.5 million blocks). The Far Lands itself is a result of noise generator bug with very large inputs [1]. [1] https://minecraft.wiki/w/Far_Lands#What_the_Far_Lands_are_not https://minecraft.wiki/w/Far_Lands#What_the_Far_Lands_are_no...
nosrepa 3y ago
I read this while wearing my kurtjmac shirt.

justinl33 3y ago

> The real issue is that there were two values where one is much larger than another, and they were combined into a single variable without further consideration. What do you mean by this? How is this related to the Far Lands generation?

xeonmc 3y ago
It's called catastrophic cancellation. Consider the following example: 999999 + 0.0000001 ~= 999999
- justinl33 3y ago
  Why doesn't it wrap around?
  - nzentzis 3y ago
    The problem is that there aren’t enough digits of precision to represent the answer. The exact answer would be 999999.0000001, but let’s say you only have space to store six significant digits. The exact answer is way more precise, so you need to round it to the nearest representable value, 999999. Floating-point rounding issues are the same thing but with binary digits instead of decimal ones.
lifthrasiir 3y ago
Graphical glitches I mentioned are independent from the Far Lands---AFAIK they start to happen around 1--2 million blocks from the origin, much closer than the Far Lands (~12.5 million blocks). The Far Lands itself is a result of noise generator bug with very large inputs [1]. [1] https://minecraft.wiki/w/Far_Lands#What_the_Far_Lands_are_not https://minecraft.wiki/w/Far_Lands#What_the_Far_Lands_are_no...

nosrepa 3y ago

I read this while wearing my kurtjmac shirt.