https://github.com/ben-wes/pd-simplex
Pure Data (Pd) external for signal and control rate simplex noise sampling with 1d, 2d, 3d and 4d input
https://github.com/ben-wes/pd-simplex
audio noise puredata simplex sound synthesis
Last synced: about 1 month ago
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Pure Data (Pd) external for signal and control rate simplex noise sampling with 1d, 2d, 3d and 4d input
- Host: GitHub
- URL: https://github.com/ben-wes/pd-simplex
- Owner: ben-wes
- License: unlicense
- Created: 2024-03-10T19:32:05.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2025-08-02T19:04:40.000Z (12 months ago)
- Last Synced: 2025-11-30T05:18:06.123Z (8 months ago)
- Topics: audio, noise, puredata, simplex, sound, synthesis
- Language: C
- Homepage:
- Size: 9.12 MB
- Stars: 5
- Watchers: 1
- Forks: 0
- Open Issues: 4
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# simplex
Pure Data (Pd) externals for signal and control rate simplex noise sampling with 1d, 2d, 3d and 4d input (signal version supporting multichannel support)
The current version's noise implementation is based on https://github.com/stegu/perlin-noise/blob/master/src/sdnoise1234.c by Stefan Gustavson.
## Build and Installation Instructions
To compile and install, follow these steps. Note that [Makefile.pdlibbuilder](https://github.com/pure-data/pd-lib-builder/) is included as submodule, requiring the `--recursive` parameter.
~~~
git clone --recursive https://github.com/ben-wes/pd-simplex.git
cd pd-simplex
make install
~~~
## Usage (simplex~)
### Inlets and Outlets
* **1st inlet:** expects a multichannel signal with up to 4 dimensions for the noise sampling position (the noise algorithm, and hence its performance, is determined by the number of channels)
* **2nd inlet:** can be used to control the persistence value with a signal or float inputs
* **outlet:** outputs the sampled noise value at signal rate
### Creation Arguments
#### Optional flags
* `-n` flag activates normalization of the octaves' sum to keep values in the [-1..1] range
* `-s ` flag initializes the noise's permutation table with a given seed
* `-d` flag activates derivatives multichannel output on additional 2nd outlet
* `-dim ` flag switches to single-channel mode with given dimension count
#### Optional numerical arguments (must be written after the flags)
* **first arg** sets the number of octaves (defaults to `1`, max. is `1024`)
* **second arg** sets initial persistence (defaults to `0.5`)
### Messages
* `[seed (` generates different (deterministic) permutation tables for the simplex function
* `[normalize 0/1(` (de)activates normalization (off by default)
* `[octaves (` dynamically changes the number of octaves
* `[persistence (` sets persistence (while no signal is connected)
* `[coeffs ... (` let's you customize the octave scaling (default is `1, 2, 4, ...`)
---
## Additional Information
### Octaves
In case of more than 1 octave, additional noise octaves get sampled, i.e., downscaled instances of the noise space (higher noise frequencies) are added. This downscaling is achieved by multiplying the sampling coordinate with `2^(octave-1)` - for example:
* input `(1, -3)` samples from `2*(1, -3) = (2, -6)` for 2nd octave
* input `(1, -3)` samples from `4*(1, -3) = (4, -12)` for 3rd octave
### Persistence
The persistence value determines the influence of successive octaves on the final output. It is a multiplier applied to each octave’s amplitude. Lower persistence values cause the amplitudes to decrease rapidly with each octave, leading to a smoother noise pattern. Conversely, higher persistence values maintain stronger amplitudes in higher octaves, resulting in more detailed and rougher (high frequency) patterns - for example:
* persistence of `0.5` yields octaves' amplitudes `1, 0.5, 0.25, 0.125, 0.0625, ...`
* persistence of `0.9` yields octaves' amplitudes `1, 0.9, 0.81, 0.729, 0.6561, ...`
### Normalization
If normalization is activated (via creation argument or message), the sum of all octaves' amplitudes is normalized to 1.
---
## History
The initial code of this external was an experiment generated with ChatGPT4. The fascinating part of this was, that with a few feedback cycles (feeding errors back to it), it managed to create a working Pd external. After some more research around simplex noise, the noise algorithm of the external turned out to be a pretty exact copy of [this SimplexNoise.cpp](https://github.com/SRombauts/SimplexNoise/blob/master/src/SimplexNoise.cpp) though (including variable names and comments). Later versions were completely revised manually though.