Correct issues with previous Seed changes #64
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This reverts commit 5bf4779.
The changes in commit ce8e06f made Seed use multiple permutation tables which resulted in a significant speed improvement. However, when using multiple tables in this style you are required to use a much larger gradient/vector table in order to get correct results. The minimum number of entries required is 64 while the ideal is 256. Doing this changes the time for a single perlin2 sample from 13ns to 4000ns which is not acceptable. As we can not properly make use of the multiple permutation tables we instead swhich back to only use one. However we are now using proper Pearson hashing instead of the variant we had before. This allows us to avoid having a double length table and seems to still offer a small benefit in speed over the old style, even if it isn't as large as multiple tables seemed to be.
As the recent changes have shown our examples do not cover a large enough area to make problems with their output immediately obvious. This changes them to the size required to see the previous problems and hopefully all future ones as well.
amaranth
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This makes me sad, but I guess there's nothing for it... |
Cifram
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Jan 12, 2015
Correct issues with previous Seed changes
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