235 lines
7.1 KiB
Python
235 lines
7.1 KiB
Python
"""
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This module provides `Paths` to create animation effects with Sprites. For more details see
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http://asciimatics.readthedocs.io/en/latest/animation.html
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"""
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from __future__ import division
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from __future__ import absolute_import
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from __future__ import print_function
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from __future__ import unicode_literals
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from future.utils import with_metaclass
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from abc import ABCMeta, abstractmethod
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from builtins import object
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from builtins import range
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def _spline(t, p0, p1, p2, p3):
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"""
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Catmull-Rom cubic spline to interpolate 4 given points.
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:param t: Time index through the spline (must be 0-1).
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:param p0: The previous point in the curve (for continuity).
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:param p1: The first point to interpolate.
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:param p2: The second point to interpolate.
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:param p3: The last point to interpolate.
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"""
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return (
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t * ((2 - t) * t - 1) * p0 +
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(t * t * (3 * t - 5) + 2) * p1 +
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t * ((4 - 3 * t) * t + 1) * p2 +
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(t - 1) * t * t * p3) / 2
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class _AbstractPath(with_metaclass(ABCMeta, object)):
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"""
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Class to represent the motion of a Sprite.
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The Screen will reset() the Path before iterating through each position
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using next_pos() and checking whether it has reached the end using
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is_finished().
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"""
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def __init__(self):
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"""
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To define a Path, use the methods to jump to a location, wait or move
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between points.
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"""
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self._steps = []
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self._index = None
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self._rec_x = 0
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self._rec_y = 0
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@abstractmethod
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def reset(self):
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"""
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Reset the Path for use next time.
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"""
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@abstractmethod
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def next_pos(self):
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"""
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:return: The next position tuple (x, y) for the Sprite on this path.
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"""
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@abstractmethod
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def is_finished(self):
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"""
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:return: Whether this path has got to the end.
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"""
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class Path(_AbstractPath):
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"""
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Class to record and play back the motion of a Sprite.
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The Screen will reset() the Path before iterating through each position
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using next_pos() and checking whether it has reached the end using
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is_finished().
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"""
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def __init__(self):
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"""
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To define a Path, use the methods to jump to a location, wait or move
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between points.
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"""
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super(Path, self).__init__()
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self._steps = []
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self._index = 0
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self._rec_x = 0
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self._rec_y = 0
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self.reset()
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def reset(self):
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"""
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Reset the Path for use next time.
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"""
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self._index = 0
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def next_pos(self):
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"""
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:return: The next position tuple (x, y) for the Sprite on this path.
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"""
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result = None
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if self._index <= len(self._steps):
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result = self._steps[self._index]
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self._index += 1
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return result
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def is_finished(self):
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"""
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:return: Whether this path has got to the end.
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"""
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return self._index >= len(self._steps)
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def _add_step(self, pos):
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"""
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Add a step to the end of the current recorded path.
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:param pos: The position tuple (x, y) to add to the list.
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"""
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self._steps.append(pos)
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self._rec_x = pos[0]
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self._rec_y = pos[1]
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def wait(self, delay):
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"""
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Wait at the current location for the specified number of iterations.
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:param delay: The time to wait (in animation frames).
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"""
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for _ in range(0, delay):
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self._add_step((self._rec_x, self._rec_y))
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def jump_to(self, x, y):
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"""
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Jump straight to the newly specified location - i.e. teleport there and
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don't create a path to get there.
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:param x: X coord for the end position.
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:param y: Y coord for the end position.
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"""
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self._add_step((x, y))
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def move_straight_to(self, x, y, steps):
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"""
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Move straight to the newly specified location - i.e. create a straight
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line Path from the current location to the specified point.
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:param x: X coord for the end position.
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:param y: Y coord for the end position.
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:param steps: How many steps to take for the move.
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"""
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start_x = self._rec_x
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start_y = self._rec_y
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for i in range(1, steps + 1):
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self._add_step((
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int(start_x + (x - start_x) / float(steps) * i),
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int(start_y + (y - start_y) / float(steps) * i)))
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def move_round_to(self, points, steps):
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"""
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Follow a path pre-defined by a set of at least 4 points. This Path will
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interpolate the points into a curve and follow that curve.
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:param points: The list of points that defines the path.
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:param steps: The number of steps to take to follow the path.
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"""
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# Spline interpolation needs a before and after point for the curve.
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# Duplicate the first and last points to handle this. We also need
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# to move from the current position to the first specified point.
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points.insert(0, (self._rec_x, self._rec_y))
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points.insert(0, (self._rec_x, self._rec_y))
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points.append(points[-1])
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# Convert the points into an interpolated set of more detailed points.
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steps_per_spline = steps // (len(points) - 3)
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for j in range(1, len(points) - 2):
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for t in range(1, steps_per_spline + 1):
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y = _spline(float(t) / steps_per_spline,
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float(points[j - 1][1]),
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float(points[j][1]),
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float(points[j + 1][1]),
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float(points[j + 2][1]))
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x = int(points[j][0] + ((points[j + 1][0] - points[j][0]) *
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float(t) / steps_per_spline))
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self._add_step((x, int(y)))
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class DynamicPath(with_metaclass(ABCMeta, _AbstractPath)):
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"""
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Class to create a dynamic path that reacts to events
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The Screen will reset() the Path before iterating through each position
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using next_pos() and checking whether it has reached the end using
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is_finished().
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"""
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def __init__(self, screen, x, y):
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"""
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To implement a DynamicPath, override the :py:meth:`.process_event()`
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method to react to any user input.
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"""
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super(DynamicPath, self).__init__()
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self._screen = screen
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self._x = self._start_x = x
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self._y = self._start_y = y
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self.reset()
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def reset(self):
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"""
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Reset the Path for use next time.
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"""
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self._x = self._start_x
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self._y = self._start_y
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def next_pos(self):
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"""
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:return: The next position tuple (x, y) for the Sprite on this path.
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"""
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return self._x, self._y
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def is_finished(self):
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"""
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:return: Whether this path has got to the end.
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"""
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return False
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@abstractmethod
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def process_event(self, event):
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"""
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Process any mouse event.
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:param event: The event that was triggered.
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:returns: None if the Effect processed the event, else the original
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event.
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"""
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