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"""
This module implements a plasma effect renderer.
"""
from math import sin, pi, sqrt
from asciimatics.renderers.base import DynamicRenderer
from asciimatics.screen import Screen
class Plasma(DynamicRenderer):
"""
Renderer to create a "plasma" effect using sinusoidal functions.
The implementation here uses the same techniques described in
http://lodev.org/cgtutor/plasma.html
"""
# The ASCII grey scale from darkest to lightest.
_greyscale = ' .:;rsA23hHG#9&@'
# Colours for different environments
_palette_8 = [
(Screen.COLOUR_BLUE, Screen.A_NORMAL),
(Screen.COLOUR_BLUE, Screen.A_NORMAL),
(Screen.COLOUR_MAGENTA, Screen.A_NORMAL),
(Screen.COLOUR_MAGENTA, Screen.A_NORMAL),
(Screen.COLOUR_RED, Screen.A_NORMAL),
(Screen.COLOUR_RED, Screen.A_BOLD),
]
_palette_256 = [
(18, 0),
(19, 0),
(20, 0),
(21, 0),
(57, 0),
(93, 0),
(129, 0),
(201, 0),
(200, 0),
(199, 0),
(198, 0),
(197, 0),
(196, 0),
(196, 0),
(196, 0),
]
def __init__(self, height, width, colours):
"""
:param height: Height of the box to contain the plasma.
:param width: Width of the box to contain the plasma.
:param colours: Number of colours the screen supports.
"""
super().__init__(height, width)
self._palette = self._palette_256 if colours >= 256 else self._palette_8
self._t = 0
def _render_now(self):
# Internal function for creating a sine wave radiating out from a point
def f(x1, y1, xp, yp, n):
return sin(sqrt((x1 - self._canvas.width * xp) ** 2 +
4 * ((y1 - self._canvas.height * yp) ** 2)) * pi / n)
self._t += 1
for y in range(self._canvas.height - 1):
for x in range(self._canvas.width - 1):
value = abs(f(x + self._t / 3, y, 1 / 4, 1 / 3, 15) +
f(x, y, 1 / 8, 1 / 5, 11) +
f(x, y + self._t / 3, 1 / 2, 1 / 5, 13) +
f(x, y, 3 / 4, 4 / 5, 13)) / 4.0
fg, attr = self._palette[
int(round(value * (len(self._palette) - 1)))]
char = self._greyscale[int((len(self._greyscale) - 1) * value)]
self._write(char, x, y, fg, attr, 0)
return self._plain_image, self._colour_map
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