// G-Force DeltaField
// Name: HAL_Quadrupole
// Created by: Howard A. Landman, 3 September 2001
// Optimized: 15-16 September 2001
// e-mail: howard@polyamory.org
// homepage: http://www.polyamory.org/~howard/

// An accident while trying to do HAL_Peacock_Tail.
// Seemed pleasant enough to keep, and simplify.

Aspc=0,

A0="0.50 + rnd(0.05) + rnd(0.05)",  // larger => more chaotic
A1="0.98 + rnd(0.01) + rnd(0.01)",  // smaller => more outward flow
A2="2*PI",
A3="1/a2",
A4="0.25",  // fraction of a circle to rotate the pattern
// If A4 is zero then the pattern has a mirror symmetry in Y
// and sensitive zone is on the left.
// I prefer it on top, so rotate by PI/2 = 1/4 of a circle.
A5="a2*a4",

// old formula (Sept.3), doesn't use a3-a4-a5.
// srcT="a0*((PI-2*abs(a2*(wrap((PI-theta)/a2)-0.5))))",

// new formula, rotated 90 degrees and optimized a bit (Sept. 15-16)
// The reason this is a bit tricky with a3 and all is to keep the "tent"
// centered as we rotate the orientation with a4 and a5.
srcT="a0*(PI - 2*abs(a2*(wrap(a3*theta + a4) - 0.5))) - a5",

srcR="a1*r",

Vers=200