# xSGE Path
# Copyright (c) 2014-2016 onpon4 <onpon4@riseup.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
xSGE is a collection of extensions for the SGE licensed under the GNU
General Public License. They are designed to give additional features
to free/libre software games which aren't necessary, but are nice to
have.
xSGE extensions are not dependent on any particular SGE implementation.
They should work with any implementation that follows the specification.
This extension provides paths for the SGE. Paths are used to make
objects move in a certain way.
"""
from __future__ import division
from __future__ import absolute_import
from __future__ import print_function
from __future__ import unicode_literals
__version__ = "1.0.1"
import math
import sge
__all__ = ["Path"]
[docs]class Path(sge.dsp.Object):
"""
Class for paths: objects which define movement patterns for other
objects. Paths are defined as a series of points for an object to
follow.
This class is derived from :class:`sge.dsp.Object` and inherits all
of that class's attributes and methods.
.. note::
:meth:`event_step` is used to implement path-following behavior.
Keep this in mind if you derive a class from this one.
.. attribute:: points
A list of the points that make up the path relative to the
position of the path in the room, excluding the first point.
Each point should be a tuple in the form ``(x, y)``, where x is
the horizontal location and y is the vertical location. The
first point is always ``(0, 0)``, which is why it is not included
in this list.
"""
[docs] def __init__(self, x, y, points=(), z=0, visible=False, tangible=False,
**kwargs):
"""
Arguments set the respective initial attributes of the object.
See the documentation for :class:`Path` for more information.
``x``, ``y``, ``z``, ``visible``, ``tangible``, and all
arguments passed to ``kwargs`` are passed as the corresponding
arguments to the constructor method of the parent class.
"""
super(Path, self).__init__(
x, y, z=z, sprite=sprite, visible=visible, tangible=tangible,
**kwargs)
self.points = list(points)
self.__objects = {}
[docs] def follow_start(self, obj, speed, accel=None, decel=None, loop=0):
"""
Cause ``obj`` to start following this path at the speed
indicated by ``speed``.
While path objects have a location within the room, this
location has no bearing on how objects following the path move.
Movement is determined relative to the location of the object
following the path when it started, not the location of the
path.
By default, the object follows the path at a constant speed.
If ``accel`` or ``decel`` is set to a value other than
:const:`None`, the object will instead accelerate or decelerate,
respectively, by that amount each frame on each segment of the
path.
``loop`` indicates the number of times the object should follow
the path after it does so the first time. For example, if set
to ``2``, the object will follow the path a total of 3 times.
Set to :const:`None` to loop indefinitely.
"""
self.__objects[id(obj)] = [obj, speed, accel, decel, obj.x, obj.y,
loop, 0]
[docs] def follow_stop(self, obj):
"""Cause ``obj`` to stop following this path."""
i = id(obj)
if i in self.__objects:
del self.__objects[i]
[docs] def event_follow_end(self, obj):
"""
Called when an object, indicated by ``obj``, finishes following
the path.
"""
pass
def event_step(self, time_passed, delta_mult):
for i in list(self.__objects.keys()):
(obj, speed, accel, decel, start_x, start_y, loop,
dest) = self.__objects[i]
dp = self.points[dest]
dx = dp[0] + start_x
dy = dp[1] + start_y
if (delta_mult and
math.hypot(dx - obj.x,
dy - obj.y) / delta_mult < obj.speed):
dest += 1
obj.speed = 0
obj.move_x(dx - obj.x)
obj.move_y(dy - obj.y)
if dest < len(self.points):
dp = self.points[dest]
dx = dp[0] + start_x
dy = dp[1] + start_y
xdist = dx - obj.x
ydist = dy - obj.y
dist = math.hypot(xdist, ydist)
md = math.atan2(ydist, xdist)
deceling = False
if decel:
decel_dist = (obj.speed ** 2) / (2 * decel)
if dist <= decel_dist:
obj.xdeceleration = -(decel * math.cos(md))
obj.ydeceleration = -(decel * math.sin(md))
deceling = True
else:
obj.xdeceleration = 0
obj.ydeceleration = 0
else:
obj.xdeceleration = 0
obj.ydeceleration = 0
if not deceling:
if accel and obj.speed < speed:
obj.xacceleration = accel * math.cos(md)
obj.yacceleration = accel * math.sin(md)
else:
obj.speed = speed
obj.move_direction = math.degrees(md)
obj.xacceleration = 0
obj.yacceleration = 0
else:
obj.xacceleration = 0
obj.yacceleration = 0
self.__objects[i] = [obj, speed, accel, decel, start_x,
start_y, loop, dest]
else:
self.follow_stop(obj)
if loop is None:
self.follow_start(obj, speed, accel, decel, None)
elif loop > 0:
self.follow_start(obj, speed, accel, decel, loop - 1)
else:
self.event_follow_end(obj)
[docs]class PathLink(Path):
"""
Class for path links. Path links are just like normal paths, but
can be linked to other path links or paths to form chains.
By using a chain of path links, you can cause an object to move in
different ways at different points of the path. For example, you
can cause the object to change its speed, or you can cause it to
accelerate and decelerate only at particular points.
.. note::
:meth:`event_follow_end` is used to implement path linking. Keep
this in mind if you derive a class from this one.
.. attribute:: next_path
The next :class:`xsge_path.Path` object to be followed after this
one. If set to :const:`None`, no additional paths will be
followed.
.. attribute:: next_speed
The value to pass on to the ``speed`` argument of the next path's
:meth:`xsge_path.Path.follow_start` call. If set to
:const:`None`, the next path will not be followed.
.. attribute:: next_accel
The value to pass on to the ``accel`` argument of the next path's
:meth:`xsge_path.Path.follow_start` call.
.. attribute:: next_decel
The value to pass on to the ``decel`` argument of the next path's
:meth:`xsge_path.Path.follow_start` call.
.. attribute:: next_loop
The value to pass on to the ``loop`` argument of the next path's
:meth:`xsge_path.Path.follow_start` call.
"""
[docs] def __init__(self, x, y, points=(), next_path=None, next_speed=None,
next_accel=None, next_decel=None, next_loop=0, z=0,
visible=False, tangible=False, **kwargs):
"""
Arguments set the respective initial attributes of the object.
See the documentation for :class:`Path` for more information.
``x``, ``y``, ``points``, ``z``, ``visible``, ``tangible``, and
all arguments passed to ``kwargs`` are passed as the
corresponding arguments to the constructor method of the parent
class.
"""
super(PathLink, self).__init__(
x, y, points=points, z=z, visible=visible, tangible=tangible,
**kwargs)
self.next_path = next_path
self.next_speed = next_speed
self.next_accel = next_accel
self.next_decel = next_decel
self.next_loop = next_loop
def event_follow_end(self, obj):
if self.next_path is not None and self.next_speed is not None:
self.next_path.follow_start(obj, self.next_speed, self.next_accel,
self.next_decel, self.next_loop)