# Rainstorm

Hybrid escape time fractal zoom made with WIP renderer using perturbation and bilinear approximation acceleration techniques.

The soundtrack is a processed field recording of raindrops on a window.

Formula: iterations of 3 functions in a loop:

z -> z^2 + c
(x+iy) -> (-x-i|y|)^2 + c
(x+iy) -> (x+i|y|)^2 + c

in a neighbourhood of

c_0 = -0.23982936275690609091987174323817759385097524674703126952518042500849137393452395591831954030142041962685077228881965218553732293014824905428884840119039024616257867560430752033277490852847796483351381166394548018933722797 + i 0.665245732118960388104849122079533500192637197646200230670491440476129417779183552014983167942558517003244663389845883956037322804165797385254263307883657973086015526458974574219020939914825441528285719869283835245322117397

final zoom factor around 1e210, maximum iteration count 8M, maximum steps per pixel 200k.

Home made software:

• fraktaler 3 to render fractal keyframes
• zoomasm to assemble video
• dr1/long to timestretch audio (inspired by phase vocoder from Pure-data)

Third party software:

• ffmpeg with x264 to encode video
• fdkaac to encode audio
• audacity for audio editing
• fftw3, sndfile for time stretcher
• gmp, mpfr, mpfrc++/mpreal for arbitrary precision numerics
• glm for maths
• openexr for image IO
• sdl2 and glfw3 for desktop windows
• glew for OpenGL
• dear imgui and imgui-filebrowser for user interface
• miniaudio for audio
• tomlplusplus and toml11 for parameter files
• gcc compiler

Hardware:

• original sound sample recorded with Zoom H4N field recorder (stereo 24bit 96kHz)
• desktop AMD Ryzen 7 2700X CPU
• graphics AMD Radeon RX 580 GPU (OpenCL for fractal calculations and OpenGL for colouring / GUI)
• external USB3 WD hard disk with ~285GB used for temporary data