Check this project out: http://www.glge.org/ It is like a port of blender's
game engine to javascript and is quite advanced.
He uses setInterval(blahBlah, 1) everywhere and after that calculates the
actual fps, so I would stick to setInterval
On Fri, Dec 16, 2011 at 4:27 AM, Nathan Sweet <nathanjsw...@gmail.com>wrote:
> >>An object that is 2 units away from a wall or a pong-paddle and that
> moves towards it at a speed of 5 units of length per page refresh will
> travel 3 units too far before a collision is detected. Worst case scenario
> is that it will go through the wall or paddle. And even if that happens the
> physics will be unrealistic. The ball won't bounce off the wall, but inside
> it.
>
> Does making the math too complex include creating an attribute or function
> attached to each object moving that can calculate where it's x and y
> coordinate will be in the next refresh? Because that could be one way to do
> it as well. If the next set of calculated coordinates meet the requisite
> definition for a collision with some other object, than you can simply put
> the object where it would be when it (theoretically) should have hit
> between refreshes; that would probably only be a calculation in differences
> between a set of x and y coordinates between two different objects.
>
>
> On Thu, Dec 15, 2011 at 5:16 PM, Lars Gunther <itpast...@gmail.com> wrote:
>
>> 2011-12-15 16:32, Nathan Sweet skrev:
>>
>> >>setInterval(function gameflow() {
>>> I think you're off to a good start with using setInterval.
>>>
>>
>> I will probably change that to setTieout later though...
>>
>>
>>
>>> >>The game should update the location of all objects 250 times/sec
>>> However, expecting to refresh rate to be 250hz is a little unrealistic.
>>> Nicholas Zakas literally just published a good article on timer
>>> resolution in browsers here it is:
>>> http://www.nczonline.net/blog/**2011/12/14/timer-resolution-**
>>> in-browsers/<http://www.nczonline.net/blog/2011/12/14/timer-resolution-in-browsers/>
>>>
>>
>> Good article. Some stuff that I'd missed. 4ms = 250 times per second I
>> had picked up from HTML5, but not that it was only for setTimeout and that
>> setInterval had a minimum of 10ms.
>>
>> Let me just explain why I want 4ms.
>>
>> An object that is 2 units away from a wall or a pong-paddle and that
>> moves towards it at a speed of 5 units of length per page refresh will
>> travel 3 units too far before a collision is detected. Worst case scenario
>> is that it will go through the wall or paddle. And even if that happens the
>> physics will be unrealistic. The ball won't bounce off the wall, but inside
>> it.
>>
>> One way to avoid that is to make the math more complex, which generally
>> does not sit well with my students. It is doable for detecting a collision
>> with a wall, but when both objects are moving the formulas will be way too
>> complicated.
>>
>> If one OTOH checks for collisions more frequently, as in 250 times per
>> second, the delta between each frame will be so small that the problems
>> will disappear. Hence my desire to separate in-memory math from on-screen
>> appearance.
>>
>>
>> Here is a good tutorial that does some simple collision detection stuff:
>>> http://billmill.org/static/**canvastutorial/<http://billmill.org/static/canvastutorial/>
>>>
>>
>> I think we've got some kind of handle on the actual collision detection
>> stuff, but I do appreciate the link.
>>
>> If I may show you guys what a student of mine is doing, have a look at
>> http://keryx.se/lab/svg/**pacman.php <http://keryx.se/lab/svg/pacman.php>
>>
>> It is being developed at
>> https://github.com/**Hasselmannen/Pacman/blob/**master/pacman.php<https://github.com/Hasselmannen/Pacman/blob/master/pacman.php>
>>
>> For this game we have no problems detecting collisions only 50 times/sec,
>> but I expect some games to have objects moving a lot faster soon.
>> https://github.com/**Hasselmannen/Pacman/blob/**master/pacman.php<https://github.com/Hasselmannen/Pacman/blob/master/pacman.php>
>>
>>
>>
>> --
>> Lars Gunther
>> http://keryx.se/
>> http://twitter.com/itpastorn/
>> http://itpastorn.blogspot.com/
>>
>> --
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