Bruce Pascoe at 06:40, 30 June 2015

2015-06-30T06:40:24Z

Bruce Pascoe: Created page with "Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmar..."

2015-06-30T06:38:43Z

Created page with "Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmar..."

New page

Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmarking or any other situation where you need higher-precision timing than [[API:GetTime|GetTime]]() can give you. A Sphere 2.0 engine such as [[minisphere]] is required to use this function.

==Usage==

{{Usage|returns=number|func=GetSeconds}}

==Examples==

<syntaxhighlight>
var time = GetSeconds();
</syntaxhighlight>

The above gets the number of seconds passed since some predetermined time, and places it in the <var>time</var> variable.

<syntaxhighlight>
var start_time = GetSeconds();
// Code that needs to be timed
// ...
var duration = GetTime() - start_time;
</syntaxhighlight>

The above example will find out how long a particular piece of code runs for.

<syntaxhighlight>
var done = false;
var fps = GetFrameRate();
var updates_performed = 0;
var start_time = GetSeconds();
while (!done)
{
while (updates_performed < (GetSeconds() - start_time) * fps)
{
// Update game here
// ...
updates_performed++;
}
// Draw the game screen here
// ...
FlipScreen();
}
</syntaxhighlight>

The above example is one way to regulate the speed of a Sphere game inside a JavaScript loop. The game code will have to be separated into updates (player input processing, moving entities, checking collisions, etc.) and drawing (drawing sprites, the map, score, etc.).

<syntaxhighlight>
var FPS = 60; // The desired FPS
var delayTime = 1.0/FPS; // The time between frames
var lastTime = GetSeconds(); // The time of the last frame
while(loopCondition) // While we should continue looping
{
if(GetSeconds() > lastTime + delayTime) // If enough time has elapsed
{
lastTime = GetSeconds(); // Record the time of this frame
doStuff(); // Do your stuff
}
drawStuff(); // Draw your stuff
}
</syntaxhighlight>

This example is an alternative to the one above. Obviously, doStuff() and drawStuff() will correspond with functions that actually process the game logic and draw the game state respectively.

==Notes==
* The starting time can be assumed to be constant throughout the running of a game. Thus GetSeconds() is very useful as a tool to pace JavaScript loops, which would normally run at different speeds on different systems.
* Core JavaScript provides a similar mechanism via the [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date Date] object's [https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime Date.getTime]() method. This counter, if used with a Date object that reflects the current time, displays the number of milliseconds since midnight 01 January, 1970 UTC. Refer to the links for more information.
* Unlike [[API:GetTime|GetTime]](), the value returned by this function is not subject to wraparound.

==See also==
* [[API:FlipScreen|FlipScreen]]()
* [[API:GetFrameRate|GetFrameRate]]()
* Core JavaScript [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date Date] object
* Core JavaScript [https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime Date.getTime]()

{{API:Script/navbox}}

@@ Line 1: / Line 1: @@
-Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmarking or any other situation where you need higher-precision timing than [[API:GetTime|GetTime]]() can give you. A Sphere 2.0 engine such as [[minisphere]] is required to use this function.
+Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmarking or any other situation where you need higher-precision timing than [[API:GetTime|GetTime]]() can give you. A '''Sphere 2.0''' engine such as [[minisphere]] is required to use this function.
 ==Usage==
@@ Line 17: / Line 17: @@
 // Code that needs to be timed
 // ...
-var duration = GetTime() - start_time;
+var duration = GetSeconds() - start_time;
 </syntaxhighlight>

Legacy:GetSeconds - Revision history

Bruce Pascoe at 06:40, 30 June 2015

Bruce Pascoe: Created page with "Obtains the amount of time in seconds, in floating point, elapsed since an arbitrary time. This function typically has sub-microsecond precision, making it useful for benchmar..."