gain_fast
Inspired by Ken Perlin's gain function, this function is a mere approximation.
However it has some interesting advantages over the original.
By removing expensive logarithm and power function calls it operates much faster
and as an added benefit it is symmetrical.
gain_fast(g,t) Returns a value t shifted towards 0 or 1 by a certain degree g resulting in an S-curve.
/*
** Usage:
** gain_fast(g,t)
**
** Arguments:
** g gain, real
** t value, real
**
** Returns:
** If (t) varies over the [0,1] interval, then
** the result also varies over that interval.
** The zero and one endpoints of the interval
** are mapped onto themselves. Regardless of
** the value of (g), all gain functions return
** 0.5 when (t) is 0.5. Above and below 0.5 the
** gain function consists of two scaled-down
** bias curves forming an S-shaped curve.
**
** GMLscripts.com
*/
{
var p;
p = (1/argument0-2)*(1-2*argument1);
if (argument1 < 0.5) return argument1/(p+1);
else return (p-argument1)/(p-1);
}
** Usage:
** gain_fast(g,t)
**
** Arguments:
** g gain, real
** t value, real
**
** Returns:
** If (t) varies over the [0,1] interval, then
** the result also varies over that interval.
** The zero and one endpoints of the interval
** are mapped onto themselves. Regardless of
** the value of (g), all gain functions return
** 0.5 when (t) is 0.5. Above and below 0.5 the
** gain function consists of two scaled-down
** bias curves forming an S-shaped curve.
**
** GMLscripts.com
*/
{
var p;
p = (1/argument0-2)*(1-2*argument1);
if (argument1 < 0.5) return argument1/(p+1);
else return (p-argument1)/(p-1);
}
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Related: bias, bias_fast, boxstep, clamp, gain, gain_fast, gammacorrect, lerp, pulse, smoothstep, spline, spline4, step
Contributor: xot
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