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 Moving Ball, Flicker Reduction
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TheXploder




PostPosted: Mon Jan 19, 2004 11:06 pm   Post subject: Moving Ball, Flicker Reduction

There are many ways to update the position of a ball one of which is
'cls' which stands for 'clear screen' I'll give you a simple tutorial on how to reduce that flicker.

The code using cls:

code:

var x : int := 0 % creates a new variable of integer type and sets the
                       % value to 0

proc objBall (x, y, ballSize, clr : int) % starts a procedure with the
% variable name 'objBall' and containing 'x, y, ballsize, clr' variables,
% which  are considered to be local variables

drawfilloval (x + ballSize, y + ballSize, ballSize, ballSize, clr)
% draws an oval

end objBall
% ends the 'objBall' procedure

loop
    objBall (x, 0, 10, 1) % "objBall's" variables that are contained can be
% called and given a value by using subscripts

    delay (10)

    x += 1 % increases x value by one each loop cycle

    cls %clears the screen
end loop

%%%%And now using a better technigue:%%%%

var x : int := 0

proc objBall (x, y, ballSize, clr : int)
      drawfilloval (x + ballSize, y + ballSize, ballSize, ballSize, clr)
end objBall

loop

    objBall (x, 0, 10, 1)
% The colour of the ball here is represented by the last number...

    delay (10)

    x += 1

% Instead of using cls this time I'll just change the colour of the ball to 0
% or white

    objBall (x, 0, 10, 0)

end loop


As you can see this reduces the fickering to a minimum. Because the screen is not redrawn completely, only were the ball previously was.

Hope this tutorial helps.. Razz
-=TheXploder=-
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Tony




PostPosted: Mon Jan 19, 2004 11:27 pm   Post subject: (No subject)

or you could just use View.Update (or now that 4.0.5 is out, View.UpdateArea) Laughing

good job for trying though+Bits
Latest from compsci.ca/blog: Tony's programming blog. DWITE - a programming contest.
Skizzarz




PostPosted: Tue Jan 20, 2004 6:54 pm   Post subject: (No subject)

thx for the great tutorial, i used some of the code in my "hockey puck" program for school and all my classmates wonder how its so smooth Laughing
Mazer




PostPosted: Tue Jan 20, 2004 7:51 pm   Post subject: Re: Moving Ball, Flicker Reduction

TheXploder wrote:

code:

    objBall (x, 0, 10, 1)
% The colour of the ball here is represented by the last number...
    delay (10)
    x += 1
% Instead of using cls this time I'll just change the colour of the ball to 0
% or white
    objBall (x, 0, 10, 0)


You should have blanked out the ball before increasing the x coordinate, otherwise you get this blue streak.
code:

    objBall (x, 0, 10, 1)
% The colour of the ball here is represented by the last number...
    delay (10)

% Instead of using cls this time I'll just change the colour of the ball to 0
% or white
    objBall (x, 0, 10, 0)
    x += 1
LiquidDragon




PostPosted: Wed Feb 18, 2004 8:16 pm   Post subject: (No subject)

well couldnt your just do something like this?

code:

View.Set ("offscreenonly")

var x : int := 0

proc objBall (x, y, ballSize, clr : int)
      drawfilloval (x + ballSize, y + ballSize, ballSize, ballSize, clr)
end objBall

loop

    objBall (x, 0, 10, 1)
        View.Update
% The colour of the ball here is represented by the last number...
    delay (10)

% Instead of using cls this time I'll just change the colour of the ball to 0
% or white
    objBall (x, 0, 10, 0)
    x += 1

end loop
Kamikagushi




PostPosted: Thu Jun 10, 2004 4:34 pm   Post subject: (No subject)

~a question~after you use View.Update~how would you turn it off~
Delos




PostPosted: Thu Jun 10, 2004 5:18 pm   Post subject: (No subject)

Repost your question in the Help forum, you'll get better answers...
nerdie




PostPosted: Mon Jun 21, 2004 3:06 pm   Post subject: (No subject)

does View.Set ("nooffscreenonly") exist?
and if it does did i spell it correctly?
GlobeTrotter




PostPosted: Mon Jun 21, 2004 3:37 pm   Post subject: (No subject)

It does exist, you spelled it right.
naoki




PostPosted: Fri Jun 25, 2004 4:36 pm   Post subject: (No subject)

View.Update is merely a one time thing, like cls. It acts by basically showing you anything drawn on the screen before View.Update was called.

Thus, you may need to call View.Update in several places of your program in order to see different things.

As well, isn't Turing set by default to nooffscreenonly? So why bother unless you set to offscreen in the first place
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