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chipanpriest

Thu Dec 29, 2011 1:59 pm


Space invaders - speed of enemies

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Hey I was wondering if there is a way to make the enemies move down slower without having a delay in the game :) thanks


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Aange10

Thu Dec 29, 2011 2:05 pm


RE:Space invaders - speed of enemies

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A: You can lower their velocity.
B: You can setup a timer.
C: You could delay it but that'd be stupid. (However in this case, you should delay it to at least 60FPS ... Time.DelaySinceLast (17)


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chipanpriest

Thu Dec 29, 2011 5:04 pm


RE:Space invaders - speed of enemies

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So Time.DelaySinceLast is just a better version of delay?? cause ive always used delay before


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Aange10

Thu Dec 29, 2011 5:43 pm


RE:Space invaders - speed of enemies

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Yes, read up on this post: http://compsci.ca/v3/viewtopic.php?t=30297


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Dreadnought

Thu Dec 29, 2011 7:57 pm


Re: Space invaders - speed of enemies

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Time.DelaySinceLast is really useful in the common situation where you would like to regulate the frequency of a loop's repetition. But it shouldn't be a direct substitute for delay, since it does not really do what delay does. Take this example:
put "Hello"
Time.DelaySinceLast(2000) % First delay
cls
for i:1..100000
    locate (1,1)
    put i
end for
put "Done!"
Time.DelaySinceLast(2000) % Second delay
cls
put "Have a nice day!"
The "second delay" is almost non-existent. So the word "Done!" might not be seen by the user. However, using Time.Delay (2000) would have made a 2 second delay each time. The functionality is not identical.

I doubt you would actually use this procedure in such a way, but I just wanted to clarify that although it is often more useful than delay, it should not be seen as a direct substitute.

As a side note, you could actually implement it yourself if you wanted to. This is the code for Time.DelaySinceLast taken directly from the code for the Time module:
var timeOfLastCall := 0
procedure DelaySinceLast (delayTime : int)
    if Time.Elapsed < timeOfLastCall + delayTime then
        Time.Delay (timeOfLastCall + delayTime - Time.Elapsed)
    end if
    timeOfLastCall := Time.Elapsed
end DelaySinceLast


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chipanpriest

Fri Dec 30, 2011 10:52 am


Re: Space invaders - speed of enemies

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This is another, kind of separate question but based on the same idea. Could i not do something like:
var t : int := Time.Elapsed
if t = 5000 then
Ey -= 20 %first row of enemies moving down
Ey2 -= 20 %second row of enemies moving down
end if


Would this work? And if so, could I somehow make it so it would move down every 5000 milliseconds without doing the code above multiple times?


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Aange10

Fri Dec 30, 2011 12:03 pm


Re: Space invaders - speed of enemies

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Indeed, here is an example of a timer.


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chipanpriest

Fri Dec 30, 2011 4:24 pm


Re: Space invaders - speed of enemies

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But what I'm trying to say is, is there a way to make something happen in intervals with only one set of code?

For example, It would be a pain to do this:
if Time.Elapsed() = 5000 then
Ey -= 1
elsif Time.Elapsed() = 10000 then
Ey -= 1
elsif Time.Elapsed() = 15000 then
Ey -= 1
%etc
%etc


Would there be a way to make it so the y value decreases every 5000 milliseconds in just one set of code instead of doing that^?


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Aange10

Fri Dec 30, 2011 5:08 pm


RE:Space invaders - speed of enemies

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Mhm.....


var timer : int := 0
loop
 if Time.Elapsed () - timer >= 5000 then
   Ey -= 1
   timer := Time.Elapsed ()
end if
end loop


Now ever 5 seconds it moves down... Just like the code in the thing I uploaded. You could hard code it all if you wanted, but whats the point?


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chipanpriest

Fri Dec 30, 2011 5:09 pm


RE:Space invaders - speed of enemies

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yea i got it thanks :D Ima upload it soon