Area fill advice

pmc · 05 October 2010, 12:08

Watcha boys

I've been doing some experimenting with blitter area fill in preparation for an effect I'm trying to do and I'm getting some weird results - check out the attached screenshots.

The screenshots show the two images that I get flickering alternately on screen when I run my experiment.

All my routine does is:

1. clears the non-displayed bitplane (using the blitter)

2. draws two vertical lines into the non-displayed bitplane (using the blitter)

3. runs an area fill (using the blitter) on the non-diplayed bitplane in an attempt to fill between the two vertical lines

4. swaps the non-displayed bitplane over with the displayed bitplane (ie. double buffering)

I know that all these routines individually work OK cos I've used them all before succesfully. I wait for the blitter to be ready prior to all uses of it.

What I'm trying to do in my experiment would seem to be very straightforward - so, any ideas why it's so epically failing...?

Lonewolf10 · 05 October 2010, 17:58

Are you sure that you aren't filling the bottom 2/3's of the screen a 2nd time?

The result looks somewhat similar to what happens when you use the blitter to fill an area filled with one colour where it has no lines to fill between. For example, the screen is all white and you use the blitter to fill it. But because every pixel is white it does something strange, that results in barcode kind of look.

Regards,
Lonewolf10

pmc · 05 October 2010, 20:16

Hey Lonewolf10

From extra testing I've done I'm pretty certain the bad results are due to some kind of issue with my filling combined with my double buffering. Take off the double buffering and the filling looks much better although overall it still doesn't look right cos it needs, err... well... double buffering.

Notice I said "my" cos the issues are undoubtedly me doing something monumentally stupid somewhere.

No matter though, I've got several effects I'm working on at the moment so I've got some spare if this turns out to be one that got away...

Kalms · 10 October 2010, 22:24

The "vertical b/w 1 pixel wide stripes" pattern is what you get if you run an XOR fill over a solid-white area.

So you are doing blit fill twice on a portion of the screen. Check your maths. And your blit start position.

pmc · 11 October 2010, 08:50

Hey Kalms

Yeah, I'd actually fixed it after spotting I had indeed been doing something monumentally stupid (see my previous post

) with my blitter pointers for my fill operation.

That's what comes from rushing a quick test together sometimes - I get blind to my own stupid errors that come from *rushing* rather than *thinking*.

Anyways man, I appreciate your advice.

05 October 2010, 12:08	#1
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Area fill advice Watcha boys I've been doing some experimenting with blitter area fill in preparation for an effect I'm trying to do and I'm getting some weird results - check out the attached screenshots. The screenshots show the two images that I get flickering alternately on screen when I run my experiment. All my routine does is: 1. clears the non-displayed bitplane (using the blitter) 2. draws two vertical lines into the non-displayed bitplane (using the blitter) 3. runs an area fill (using the blitter) on the non-diplayed bitplane in an attempt to fill between the two vertical lines 4. swaps the non-displayed bitplane over with the displayed bitplane (ie. double buffering) I know that all these routines individually work OK cos I've used them all before succesfully. I wait for the blitter to be ready prior to all uses of it. What I'm trying to do in my experiment would seem to be very straightforward - so, any ideas why it's so epically failing...? Last edited by pmc; 20 November 2010 at 10:41.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Blitter fill timing	leonard	Coders. Asm / Hardware	42	01 September 2014 11:00
80 GB HD to fill!	fatboy	Amiga scene	16	20 July 2011 14:13
Sector fill pattern	absence	Coders. General	7	21 March 2009 21:50
A few fish needed to fill my tank...	Severin	request.Apps	7	16 August 2003 14:36
Fill 'em	Tim Janssen	request.Old Rare Games	1	27 June 2003 09:25

05 October 2010, 17:58	#2
Lonewolf10 AMOS Extensions Developer Join Date: Jun 2007 Location: near Cambridge, UK Age: 44 Posts: 1,924	Are you sure that you aren't filling the bottom 2/3's of the screen a 2nd time? The result looks somewhat similar to what happens when you use the blitter to fill an area filled with one colour where it has no lines to fill between. For example, the screen is all white and you use the blitter to fill it. But because every pixel is white it does something strange, that results in barcode kind of look. Regards, Lonewolf10

05 October 2010, 20:16	#3
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Hey Lonewolf10 From extra testing I've done I'm pretty certain the bad results are due to some kind of issue with my filling combined with my double buffering. Take off the double buffering and the filling looks much better although overall it still doesn't look right cos it needs, err... well... double buffering. Notice I said "my" cos the issues are undoubtedly me doing something monumentally stupid somewhere. No matter though, I've got several effects I'm working on at the moment so I've got some spare if this turns out to be one that got away...

10 October 2010, 22:24	#4
Kalms Registered User Join Date: Nov 2006 Location: Stockholm, Sweden Posts: 237	The "vertical b/w 1 pixel wide stripes" pattern is what you get if you run an XOR fill over a solid-white area. So you are doing blit fill twice on a portion of the screen. Check your maths. And your blit start position.

11 October 2010, 08:50	#5
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	Hey Kalms Yeah, I'd actually fixed it after spotting I had indeed been doing something monumentally stupid (see my previous post ) with my blitter pointers for my fill operation. That's what comes from rushing a quick test together sometimes - I get blind to my own stupid errors that come from rushing rather than thinking. Anyways man, I appreciate your advice.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)