NAME¶
Math::Gradient - Perl extension for calculating gradients for colour
transitions, etc.
SYNOPSIS¶
use Math::Gradient qw(multi_gradient);
# make a 100-point colour palette to smothly transition between 6 RGB values
my(@hot_spots) = ([ 0, 255, 0 ], [ 255, 255, 0 ], [ 127, 127, 127 ], [ 0, 0, 255
], [ 127, 0, 0 ], [ 255, 255, 255 ]);
my(@gradient) = multi_array_gradient(100, @hot_spots);
DESCRIPTION¶
Math::Gradient is used to calculate smooth transitions between numerical values
(also known as a "Gradient"). I wrote this module mainly to mix
colours, but it probably has several other applications. Methods are supported
to handle both basic and multiple-point gradients, both with scalars and
arrays.
FUNCTIONS¶
- gradient($start_value, $end_value, $steps)
- This function will return an array of evenly distributed values between
$start_value and $end_value. All three values supplied should be numeric.
$steps should be the number of steps that should occur between the two
points; for instance, gradient(0, 10, 4) would return the array (2, 4, 6,
8); the 4 evenly-distributed steps necessary to get from 0 to 10, whereas
gradient(0, 1, 3) would return (0.25, 0.5, 0.75). This is the basest
function in the Math::Gradient module and isn't very exciting, but all of
the other functions below derive their work from it.
- array_gradient($start_value, $end_value, $steps)
- While gradient() takes numeric values for $start_value and
$end_value, array_gradient() takes arrayrefs instead. The arrays
supplied are expected to be lists of numerical values, and all of the
arrays should contain the same number of elements. array_gradient()
will return a list of arrayrefs signifying the gradient of all values on
the lists $start_value and $end_value.
For example, calling array_gradient([ 0, 100, 2 ], [ 100, 50, 70], 3) would
return: ([ 25, 87.5, 19 ], [ 50, 75, 36 ], [ 75, 62.5, 53 ]).
- multi_gradient($steps, @values)
- multi_gradient() calculates multiple gradients at once, returning
one list that is an even transition between all points, with the values
supplied interpolated evenly within the list. If $steps is less than the
number of entries in the list @values, items are deleted from @values
instead.
For example, calling multi_gradient(10, 0, 100, 50) would return: (0, 25,
50, 75, 100, 90, 80, 70, 60, 50)
- multi_array_gradient($steps, @values)
- multi_array_gradient() is the same as multi_gradient, except that
it works on arrayrefs instead of scalars (like array_gradient() is
to gradient()).
AUTHOR¶
Tyler MacDonald, <japh@crackerjack.net>
COPYRIGHT AND LICENSE¶
Copyright 2003 by Tyler MacDonald
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.