# ---------------------------------------------------------------------------- # pyglet # Copyright (c) 2006-2008 Alex Holkner # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions # are met: # # * Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in # the documentation and/or other materials provided with the # distribution. # * Neither the name of pyglet nor the names of its # contributors may be used to endorse or promote products # derived from this software without specific prior written # permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. # ---------------------------------------------------------------------------- '''Precise framerate calculation, scheduling and framerate limiting. Measuring time ============== The `tick` and `get_fps` functions can be used in conjunction to fulfil most games' basic requirements:: from pylet import clock while True: dt = clock.tick() # ... update and render ... print 'FPS is %f' % clock.get_fps() The ``dt`` value returned gives the number of seconds (as a float) since the last "tick". The `get_fps` function averages the framerate over a sliding window of approximately 1 second. (You can calculate the instantaneous framerate by taking the reciprocal of ``dt``). Always remember to `tick` the clock! Limiting frame-rate =================== The framerate can be limited:: clock.set_fps_limit(60) This causes `clock` to sleep during each `tick` in an attempt to keep the number of ticks (frames) per second below 60. The implementation uses platform-dependent high-resolution sleep functions to achieve better accuracy with busy-waiting than would be possible using just the `time` module. Scheduling ========== You can schedule a function to be called every time the clock is ticked:: def callback(dt): print '%f seconds since last callback' % dt clock.schedule(callback) The `schedule_interval` method causes a function to be called every "n" seconds:: clock.schedule_interval(callback, .5) # called twice a second The `schedule_once` method causes a function to be called once "n" seconds in the future:: clock.schedule_once(callback, 5) # called in 5 seconds All of the `schedule` methods will pass on any additional args or keyword args you specify ot the callback function:: def animate(dt, velocity, sprite): sprite.position += dt * velocity clock.schedule(animate, velocity=5.0, sprite=alien) You can cancel a function scheduled with any of these methods using `unschedule`:: clock.unschedule(animate) Displaying FPS ============== The ClockDisplay class provides a simple FPS counter. You should create an instance of ClockDisplay once during the application's start up:: fps_display = clock.ClockDisplay() Call draw on the ClockDisplay object for each frame:: fps_display.draw() There are several options to change the font, color and text displayed within the __init__ method. Using multiple clocks ===================== The clock functions are all relayed to an instance of `Clock` which is initalised with the module. You can get this instance to use directly:: clk = clock.get_default() You can also replace the default clock with your own: myclk = clock.Clock() clock.set_default(myclk) Each clock maintains its own set of scheduled functions and FPS limiting/measurement. Each clock must be "ticked" separately. Multiple and derived clocks potentially allow you to separate "game-time" and "wall-time", or to synchronise your clock to an audio or video stream instead of the system clock. ''' __docformat__ = 'restructuredtext' __version__ = '$Id: clock.py 2298 2008-10-06 09:13:09Z Alex.Holkner $' import time import sys import operator import ctypes import ctypes.util import pyglet.lib if sys.platform in ('win32', 'cygwin'): # Win32 Sleep function is only 10-millisecond resolution, so instead # use a waitable timer object, which has up to 100-nanosecond resolution # (hardware and implementation dependent, of course). _kernel32 = ctypes.windll.kernel32 class _ClockBase(object): def __init__(self): self._timer = _kernel32.CreateWaitableTimerA(ctypes.c_void_p(), True, ctypes.c_void_p()) def sleep(self, microseconds): delay = ctypes.c_longlong(int(-microseconds * 10)) _kernel32.SetWaitableTimer(self._timer, ctypes.byref(delay), 0, ctypes.c_void_p(), ctypes.c_void_p(), False) _kernel32.WaitForSingleObject(self._timer, 0xffffffff) else: _c = pyglet.lib.load_library('c', darwin='/usr/lib/libc.dylib') _c.usleep.argtypes = [ctypes.c_ulong] class _ClockBase(object): def sleep(self, microseconds): _c.usleep(int(microseconds)) class _ScheduledItem(object): __slots__ = ['func', 'args', 'kwargs'] def __init__(self, func, args, kwargs): self.func = func self.args = args self.kwargs = kwargs class _ScheduledIntervalItem(object): __slots__ = ['func', 'interval', 'last_ts', 'next_ts', 'args', 'kwargs'] def __init__(self, func, interval, last_ts, next_ts, args, kwargs): self.func = func self.interval = interval self.last_ts = last_ts self.next_ts = next_ts self.args = args self.kwargs = kwargs def _dummy_schedule_func(*args, **kwargs): '''Dummy function that does nothing, placed onto zombie scheduled items to ensure they have no side effect if already queued inside tick() method. ''' pass class Clock(_ClockBase): '''Class for calculating and limiting framerate, and for calling scheduled functions. ''' #: The minimum amount of time in seconds this clock will attempt to sleep #: for when framerate limiting. Higher values will increase the #: accuracy of the limiting but also increase CPU usage while #: busy-waiting. Lower values mean the process sleeps more often, but is #: prone to over-sleep and run at a potentially lower or uneven framerate #: than desired. MIN_SLEEP = 0.005 #: The amount of time in seconds this clock subtracts from sleep values #: to compensate for lazy operating systems. SLEEP_UNDERSHOOT = MIN_SLEEP - 0.001 # List of functions to call every tick. _schedule_items = None # List of schedule interval items kept in sort order. _schedule_interval_items = None # If True, a sleep(0) is inserted on every tick. _force_sleep = False def __init__(self, fps_limit=None, time_function=time.time): '''Initialise a Clock, with optional framerate limit and custom time function. :Parameters: `fps_limit` : float If not None, the maximum allowable framerate. Defaults to None. Deprecated in pyglet 1.1. `time_function` : function Function to return the elapsed time of the application, in seconds. Defaults to time.time, but can be replaced to allow for easy time dilation effects or game pausing. ''' super(Clock, self).__init__() self.time = time_function self.next_ts = self.time() self.last_ts = None self.times = [] self.set_fps_limit(fps_limit) self.cumulative_time = 0 self._schedule_items = [] self._schedule_interval_items = [] def tick(self, poll=False): '''Signify that one frame has passed. This will call any scheduled functions that have elapsed. :Parameters: `poll` : bool If True, the function will call any scheduled functions but will not sleep or busy-wait for any reason. Recommended for advanced applications managing their own sleep timers only. Since pyglet 1.1. :rtype: float :return: The number of seconds since the last "tick", or 0 if this was the first frame. ''' if poll: if self.period_limit: self.next_ts = self.next_ts + self.period_limit else: if self.period_limit: self._limit() if self._force_sleep: self.sleep(0) ts = self.time() if self.last_ts is None: delta_t = 0 else: delta_t = ts - self.last_ts self.times.insert(0, delta_t) if len(self.times) > self.window_size: self.cumulative_time -= self.times.pop() self.cumulative_time += delta_t self.last_ts = ts # Call functions scheduled for every frame # Dupe list just in case one of the items unchedules itself for item in list(self._schedule_items): item.func(delta_t, *item.args, **item.kwargs) # Call all scheduled interval functions and reschedule for future. need_resort = False # Dupe list just in case one of the items unchedules itself for item in list(self._schedule_interval_items): if item.next_ts > ts: break item.func(ts - item.last_ts, *item.args, **item.kwargs) if item.interval: # Try to keep timing regular, even if overslept this time; # but don't schedule in the past (which could lead to # infinitely-worsing error). item.next_ts = item.last_ts + item.interval item.last_ts = ts if item.next_ts <= ts: if ts - item.next_ts < 0.05: # Only missed by a little bit, keep the same schedule item.next_ts = ts + item.interval else: # Missed by heaps, do a soft reschedule to avoid # lumping everything together. item.next_ts = self._get_soft_next_ts(ts, item.interval) # Fake last_ts to avoid repeatedly over-scheduling in # future. Unfortunately means the next reported dt is # incorrect (looks like interval but actually isn't). item.last_ts = item.next_ts - item.interval need_resort = True else: item.next_ts = None # Remove finished one-shots. self._schedule_interval_items = \ [item for item in self._schedule_interval_items \ if item.next_ts is not None] if need_resort: # TODO bubble up changed items might be faster self._schedule_interval_items.sort(key=lambda a: a.next_ts) return delta_t def _limit(self): '''Sleep until the next frame is due. Called automatically by `tick` if a framerate limit has been set. This method uses several heuristics to determine whether to sleep or busy-wait (or both). ''' ts = self.time() # Sleep to just before the desired time sleeptime = self.get_sleep_time(False) while sleeptime - self.SLEEP_UNDERSHOOT > self.MIN_SLEEP: self.sleep(1000000 * (sleeptime - self.SLEEP_UNDERSHOOT)) sleeptime = self.get_sleep_time(False) # Busy-loop CPU to get closest to the mark sleeptime = self.next_ts - self.time() while sleeptime > 0: sleeptime = self.next_ts - self.time() if sleeptime < -2 * self.period_limit: # Missed the time by a long shot, let's reset the clock # print >> sys.stderr, 'Step %f' % -sleeptime self.next_ts = ts + 2 * self.period_limit else: # Otherwise keep the clock steady self.next_ts = self.next_ts + self.period_limit def get_sleep_time(self, sleep_idle): '''Get the time until the next item is scheduled. This method considers all scheduled items and the current ``fps_limit``, if any. Applications can choose to continue receiving updates at the maximum framerate during idle time (when no functions are scheduled), or they can sleep through their idle time and allow the CPU to switch to other processes or run in low-power mode. If `sleep_idle` is ``True`` the latter behaviour is selected, and ``None`` will be returned if there are no scheduled items. Otherwise, if `sleep_idle` is ``False``, a sleep time allowing the maximum possible framerate (considering ``fps_limit``) will be returned; or an earlier time if a scheduled function is ready. :Parameters: `sleep_idle` : bool If True, the application intends to sleep through its idle time; otherwise it will continue ticking at the maximum frame rate allowed. :rtype: float :return: Time until the next scheduled event in seconds, or ``None`` if there is no event scheduled. :since: pyglet 1.1 ''' if self._schedule_items or not sleep_idle: if not self.period_limit: return 0. else: wake_time = self.next_ts if self._schedule_interval_items: wake_time = min(wake_time, self._schedule_interval_items[0].next_ts) return max(wake_time - self.time(), 0.) if self._schedule_interval_items: return max(self._schedule_interval_items[0].next_ts - self.time(), 0) return None def set_fps_limit(self, fps_limit): '''Set the framerate limit. The framerate limit applies only when a function is scheduled for every frame. That is, the framerate limit can be exceeded by scheduling a function for a very small period of time. :Parameters: `fps_limit` : float Maximum frames per second allowed, or None to disable limiting. :deprecated: Use `pyglet.app.run` and `schedule_interval` instead. ''' if not fps_limit: self.period_limit = None else: self.period_limit = 1. / fps_limit self.window_size = fps_limit or 60 def get_fps_limit(self): '''Get the framerate limit. :rtype: float :return: The framerate limit previously set in the constructor or `set_fps_limit`, or None if no limit was set. ''' if self.period_limit: return 1. / self.period_limit else: return 0 def get_fps(self): '''Get the average FPS of recent history. The result is the average of a sliding window of the last "n" frames, where "n" is some number designed to cover approximately 1 second. :rtype: float :return: The measured frames per second. ''' if not self.cumulative_time: return 0 return len(self.times) / self.cumulative_time def schedule(self, func, *args, **kwargs): '''Schedule a function to be called every frame. The function should have a prototype that includes ``dt`` as the first argument, which gives the elapsed time, in seconds, since the last clock tick. Any additional arguments given to this function are passed on to the callback:: def callback(dt, *args, **kwargs): pass :Parameters: `func` : function The function to call each frame. ''' item = _ScheduledItem(func, args, kwargs) self._schedule_items.append(item) def _schedule_item(self, func, last_ts, next_ts, interval, *args, **kwargs): item = _ScheduledIntervalItem( func, interval, last_ts, next_ts, args, kwargs) # Insert in sort order for i, other in enumerate(self._schedule_interval_items): if other.next_ts > next_ts: self._schedule_interval_items.insert(i, item) break else: self._schedule_interval_items.append(item) def schedule_interval(self, func, interval, *args, **kwargs): '''Schedule a function to be called every `interval` seconds. Specifying an interval of 0 prevents the function from being called again (see `schedule` to call a function as often as possible). The callback function prototype is the same as for `schedule`. :Parameters: `func` : function The function to call when the timer lapses. `interval` : float The number of seconds to wait between each call. ''' last_ts = self.last_ts or self.next_ts # Schedule from now, unless now is sufficiently close to last_ts, in # which case use last_ts. This clusters together scheduled items that # probably want to be scheduled together. The old (pre 1.1.1) # behaviour was to always use self.last_ts, and not look at ts. The # new behaviour is needed because clock ticks can now be quite # irregular, and span several seconds. ts = self.time() if ts - last_ts > 0.2: last_ts = ts next_ts = last_ts + interval self._schedule_item(func, last_ts, next_ts, interval, *args, **kwargs) def schedule_interval_soft(self, func, interval, *args, **kwargs): '''Schedule a function to be called every `interval` seconds, beginning at a time that does not coincide with other scheduled events. This method is similar to `schedule_interval`, except that the clock will move the interval out of phase with other scheduled functions so as to distribute CPU more load evenly over time. This is useful for functions that need to be called regularly, but not relative to the initial start time. `pyglet.media` does this for scheduling audio buffer updates, which need to occur regularly -- if all audio updates are scheduled at the same time (for example, mixing several tracks of a music score, or playing multiple videos back simultaneously), the resulting load on the CPU is excessive for those intervals but idle outside. Using the soft interval scheduling, the load is more evenly distributed. Soft interval scheduling can also be used as an easy way to schedule graphics animations out of phase; for example, multiple flags waving in the wind. :since: pyglet 1.1 :Parameters: `func` : function The function to call when the timer lapses. `interval` : float The number of seconds to wait between each call. ''' last_ts = self.last_ts or self.next_ts # See schedule_interval ts = self.time() if ts - last_ts > 0.2: last_ts = ts next_ts = self._get_soft_next_ts(last_ts, interval) last_ts = next_ts - interval self._schedule_item(func, last_ts, next_ts, interval, *args, **kwargs) def _get_soft_next_ts(self, last_ts, interval): def taken(ts, e): '''Return True if the given time has already got an item scheduled nearby. ''' for item in self._schedule_interval_items: if abs(item.next_ts - ts) <= e: return True elif item.next_ts > ts + e: return False return False # Binary division over interval: # # 0 interval # |--------------------------| # 5 3 6 2 7 4 8 1 Order of search # # i.e., first scheduled at interval, # then at interval/2 # then at interval/4 # then at interval*3/4 # then at ... # # Schedule is hopefully then evenly distributed for any interval, # and any number of scheduled functions. next_ts = last_ts + interval if not taken(next_ts, interval / 4): return next_ts dt = interval divs = 1 while True: next_ts = last_ts for i in range(divs - 1): next_ts += dt if not taken(next_ts, dt / 4): return next_ts dt /= 2 divs *= 2 # Avoid infinite loop in pathological case if divs > 16: return next_ts def schedule_once(self, func, delay, *args, **kwargs): '''Schedule a function to be called once after `delay` seconds. The callback function prototype is the same as for `schedule`. :Parameters: `func` : function The function to call when the timer lapses. `delay` : float The number of seconds to wait before the timer lapses. ''' last_ts = self.last_ts or self.next_ts # See schedule_interval ts = self.time() if ts - last_ts > 0.2: last_ts = ts next_ts = last_ts + delay self._schedule_item(func, last_ts, next_ts, 0, *args, **kwargs) def unschedule(self, func): '''Remove a function from the schedule. If the function appears in the schedule more than once, all occurances are removed. If the function was not scheduled, no error is raised. :Parameters: `func` : function The function to remove from the schedule. ''' # First replace zombie items' func with a dummy func that does # nothing, in case the list has already been cloned inside tick(). # (Fixes issue 326). for item in self._schedule_items: if item.func == func: item.func = _dummy_schedule_func for item in self._schedule_interval_items: if item.func == func: item.func = _dummy_schedule_func # Now remove matching items from both schedule lists. self._schedule_items = \ [item for item in self._schedule_items \ if item.func is not _dummy_schedule_func] self._schedule_interval_items = \ [item for item in self._schedule_interval_items \ if item.func is not _dummy_schedule_func] # Default clock. _default = Clock() def set_default(default): '''Set the default clock to use for all module-level functions. By default an instance of `Clock` is used. :Parameters: `default` : `Clock` The default clock to use. ''' global _default _default = default def get_default(): '''Return the `Clock` instance that is used by all module-level clock functions. :rtype: `Clock` :return: The default clock. ''' return _default def tick(poll=False): '''Signify that one frame has passed on the default clock. This will call any scheduled functions that have elapsed. :Parameters: `poll` : bool If True, the function will call any scheduled functions but will not sleep or busy-wait for any reason. Recommended for advanced applications managing their own sleep timers only. Since pyglet 1.1. :rtype: float :return: The number of seconds since the last "tick", or 0 if this was the first frame. ''' return _default.tick(poll) def get_sleep_time(sleep_idle): '''Get the time until the next item is scheduled on the default clock. See `Clock.get_sleep_time` for details. :Parameters: `sleep_idle` : bool If True, the application intends to sleep through its idle time; otherwise it will continue ticking at the maximum frame rate allowed. :rtype: float :return: Time until the next scheduled event in seconds, or ``None`` if there is no event scheduled. :since: pyglet 1.1 ''' return _default.get_sleep_time(sleep_idle) def get_fps(): '''Return the current measured FPS of the default clock. :rtype: float ''' return _default.get_fps() def set_fps_limit(fps_limit): '''Set the framerate limit for the default clock. :Parameters: `fps_limit` : float Maximum frames per second allowed, or None to disable limiting. :deprecated: Use `pyglet.app.run` and `schedule_interval` instead. ''' _default.set_fps_limit(fps_limit) def get_fps_limit(): '''Get the framerate limit for the default clock. :return: The framerate limit previously set by `set_fps_limit`, or None if no limit was set. ''' return _default.get_fps_limit() def schedule(func, *args, **kwargs): '''Schedule 'func' to be called every frame on the default clock. The arguments passed to func are ``dt``, followed by any ``*args`` and ``**kwargs`` given here. :Parameters: `func` : function The function to call each frame. ''' _default.schedule(func, *args, **kwargs) def schedule_interval(func, interval, *args, **kwargs): '''Schedule 'func' to be called every 'interval' seconds on the default clock. The arguments passed to 'func' are 'dt' (time since last function call), followed by any ``*args`` and ``**kwargs`` given here. :Parameters: `func` : function The function to call when the timer lapses. `interval` : float The number of seconds to wait between each call. ''' _default.schedule_interval(func, interval, *args, **kwargs) def schedule_interval_soft(func, interval, *args, **kwargs): '''Schedule 'func' to be called every 'interval' seconds on the default clock, beginning at a time that does not coincide with other scheduled events. The arguments passed to 'func' are 'dt' (time since last function call), followed by any ``*args`` and ``**kwargs`` given here. :see: `Clock.schedule_interval_soft` :since: pyglet 1.1 :Parameters: `func` : function The function to call when the timer lapses. `interval` : float The number of seconds to wait between each call. ''' _default.schedule_interval_soft(func, interval, *args, **kwargs) def schedule_once(func, delay, *args, **kwargs): '''Schedule 'func' to be called once after 'delay' seconds (can be a float) on the default clock. The arguments passed to 'func' are 'dt' (time since last function call), followed by any ``*args`` and ``**kwargs`` given here. If no default clock is set, the func is queued and will be scheduled on the default clock as soon as it is created. :Parameters: `func` : function The function to call when the timer lapses. `delay` : float The number of seconds to wait before the timer lapses. ''' _default.schedule_once(func, delay, *args, **kwargs) def unschedule(func): '''Remove 'func' from the default clock's schedule. No error is raised if the func was never scheduled. :Parameters: `func` : function The function to remove from the schedule. ''' _default.unschedule(func) class ClockDisplay(object): '''Display current clock values, such as FPS. This is a convenience class for displaying diagnostics such as the framerate. See the module documentation for example usage. :Ivariables: `label` : `pyglet.font.Text` The label which is displayed. ''' def __init__(self, font=None, interval=0.25, format='%(fps).2f', color=(.5, .5, .5, .5), clock=None): '''Create a ClockDisplay. All parameters are optional. By default, a large translucent font will be used to display the FPS to two decimal places. :Parameters: `font` : `pyglet.font.Font` The font to format text in. `interval` : float The number of seconds between updating the display. `format` : str A format string describing the format of the text. This string is modulated with the dict ``{'fps' : fps}``. `color` : 4-tuple of float The color, including alpha, passed to ``glColor4f``. `clock` : `Clock` The clock which determines the time. If None, the default clock is used. ''' if clock is None: clock = _default self.clock = clock self.clock.schedule_interval(self.update_text, interval) if not font: from pyglet.font import load as load_font font = load_font('', 36, bold=True) import pyglet.font self.label = pyglet.font.Text(font, '', color=color, x=10, y=10) self.format = format def unschedule(self): '''Remove the display from its clock's schedule. `ClockDisplay` uses `Clock.schedule_interval` to periodically update its display label. Even if the ClockDisplay is not being used any more, its update method will still be scheduled, which can be a resource drain. Call this method to unschedule the update method and allow the ClockDisplay to be garbage collected. :since: pyglet 1.1 ''' self.clock.unschedule(self.update_text) def update_text(self, dt=0): '''Scheduled method to update the label text.''' fps = self.clock.get_fps() self.label.text = self.format % {'fps': fps} def draw(self): '''Method called each frame to render the label.''' self.label.draw() def test_clock(): import sys import getopt test_seconds = 1 test_fps = 60 show_fps = False options, args = getopt.getopt(sys.argv[1:], 'vht:f:', ['time=', 'fps=', 'help']) for key, value in options: if key in ('-t', '--time'): test_seconds = float(value) elif key in ('-f', '--fps'): test_fps = float(value) elif key in ('-v'): show_fps = True elif key in ('-h', '--help'): print ('Usage: clock.py \n' '\n' 'Options:\n' ' -t --time Number of seconds to run for.\n' ' -f --fps Target FPS.\n' '\n' 'Tests the clock module by measuring how close we can\n' 'get to the desired FPS by sleeping and busy-waiting.') sys.exit(0) set_fps_limit(test_fps) start = time.time() # Add one because first frame has no update interval. n_frames = int(test_seconds * test_fps + 1) print 'Testing %f FPS for %f seconds...' % (test_fps, test_seconds) for i in xrange(n_frames): tick() if show_fps: print get_fps() total_time = time.time() - start total_error = total_time - test_seconds print 'Total clock error: %f secs' % total_error print 'Total clock error / secs: %f secs/secs' % \ (total_error / test_seconds) # Not fair to add the extra frame in this calc, since no-one's interested # in the startup situation. print 'Average FPS: %f' % ((n_frames - 1) / total_time) if __name__ == '__main__': test_clock()