This block experiments SimplexNoise (see also 2, 1). More particularly, how to produce a continous radial noise.

Work initiated by this block from elenstar, Drawing Vector Field, and the outstanding Neonflames.

In this block, I use SimplexNoise to produce each radiationâ€™s shape and growth. The shape is composed of lines joining several verteces. Verteces evolve thanks to values produced with SimplexNoise. **The challenge was to compute a continuous noise between the first few verteces (from 0 rad) and the last few verteces (before 2*PI)**. The technique I use is:

- define 2 noise functions; 1 discontinued around 0 rad, and 1 discontinued around PI
- mix the 2 noises so that:
- around 0 rad, only the second noise is used (discontinuity of the first noise is eliminated)
- around PI, only the first noise is used (discontinuity of the second noise is eliminated)
- for other angles, use a smooth mix of the 2 noises (I use a cos-based function)

The Simplex Wave + Explanations block explains this technique in a more appealing way (with drawings ;-).

This block is also the first one that allows me to use SimplexNoise with polar coordinates (instead of cartesian coordinates). Noise depends on *r* and *θ* (intead of the more classical *x* and *y*).

#### Acknowledgments to: