One of the most visited articles on our site – How to Use Perlin Noise in Your Games – also caused the most problems. The pseudo-code contained an alarming number of bugs (one of the nastier ones is depicted above), which made it difficult to implement. Readers pointed out these in the comments, and so helped to make the pseudo-code progressively more correct. But even so, some operations remained unclear, so that I finally decided to replace the pseudo-code with real and tested code. I really hope that all bugs have now been squashed!
In the spirit of this extermination effort, this article gives some pointers to get a version of the algorithm up and running as quickly as possible. It is an extension of the original Perlin noise article, and refers to the code now presented there.