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  2D scrolling problem...  (Read 3445 times)
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Offline Max Pesce

Junior Devvie

Nil tam arduum quod non ingenio vincas

« Posted 2002-11-12 14:16:18 »


I've coded a scrolling routine in the simplest way:
I draw a grid of blocks (tiles) translated "ad hoc" to
simulate the movement. This routine works fine but it's
not the best way to do a scrolling (Am I wrong?).
So I'm trying to make a delta-scrolling:
I scroll the screen graphics and then past only the
blocks on the borders of the screen (there is a great
increase of fps).
This technique worked fine on C++ and DX, but doesn't
work on Java!

The problem could be in Graphics.copyArea() function...
When I scroll graphics to right (so the map is moving to left)
it scrolls fine, but when the graphics srolls to left,
the scrolling hangs after few pixels (about 64) and then
it scrolls one pixel after many millisec (randomly).

I can't understand why it happens, is it a bug of Java?
I'm using JDK 1.4.0_01.

Another thing I've noticed is that if I replace the
call to copyArea() with an own made routine (using
drawImage) the result is the same!
So the problem is probably in the Java2D API..

Could anyone give me a solution?

Offline zparticle

Senior Devvie

Thick As A Brick

« Reply #1 - Posted 2002-11-12 14:35:53 »

There was a bug in JDK 1.2 I think where copyArea freaked out on negative values. It was supposed to be fixed. My guess is you have a logic problem. Can you post some code?

Offline Micke

Senior Newbie


« Reply #2 - Posted 2002-11-13 06:12:45 »

Take a look in this thread:;action=display;num=1034928727

(And vote for the bug!)

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Offline Max Pesce

Junior Devvie

Nil tam arduum quod non ingenio vincas

« Reply #3 - Posted 2002-11-14 10:18:56 »

I've tried the solution given in the topic suggested by Micke, it was very similar to mine...
The result is the same!!!

The code as I said is very very similar to the one given in
the topic..

There are slowdowns when scrolling left and down!

I'm gonna vote for the bug on the Sun site...
But now? what I should do?
I must use the slow version for a while.

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