Problems with displaying a screen!

[Havie]

Help - problem driving me mad!

I am simply trying to display a background (320x200 16 colours) on a double buffered screen. When I run the program - it works first time but when it ends I get an error (#80000020) or if I leave it a while it just crashes. If I reload and rerun the program it just crashes and seems to be trying to display the bitmap in different parts of the memory (if that makes sense). If after running once, I reload the bitmap into Deluxe Paint and re-save it then the program runs and crashes again. Whatever is happening initially seems to be corrupting my iff file.

I'm probably doing something stupid - help. Here is the code:

WBStartup

LoadShape 50,"Background/level1"
LoadPalette 0,"Graphics/palette.pal"

BLITZ

;set up bitmap...
;
BitMap 0,320+16,200,4
BitMap 1,320+16,200,4

InitCopList 0,44,200,$14,8,32,0
DisplayPalette 0,0
CreateDisplay 0

DisplayBitMap 0,0

db=0

Use BitMap 0: Blit 50,0,0
Use BitMap 1: Blit 50,0,0

;while mouse button not hit

While RawStatus(69)=0

	VWait
	Displaybitmap 0, db

	db=1-db

Wend

[Cobe]

Well if you already enabled smooth scrolling I think you'd be better of using extended Displaybitmap 0,db,0,0.
Though I find Blitz unexplainable from time to time so if its something else I'd like to know.

[Havie]

Thanks - but gives the same error.

[Cobe]

then I'd go with unexplainabel.. Did you try loadshape 0 instead 50? And is your picture 16 or 32 colors? You're setting 4 bitplanes then setting 32 colors..

[idrougge]

Is "level1" a shape or an IFF ILBM picture?

[Daedalus]

There can be issues with memory corruption when shapes are too large. Try loading a smaller shape for Level1 and see if that helps. If so, you can perhaps load it in chunks, or else use LoadBitmap to load the background instead.

[Havie]

Originally Posted by Daedalus

There can be issues with memory corruption when shapes are too large. Try loading a smaller shape for Level1 and see if that helps. If so, you can perhaps load it in chunks, or else use LoadBitmap to load the background instead.

After 3 days of trying I was coming to the same conclusion. Will try loading bitmap instead!

[Havie]

As usual your are right D - was definitely something to do with memory issues. Loading the bitmap directly does the job.

Thanks again!

[Havie]

Originally Posted by Cobe

then I'd go with unexplainabel.. Did you try loadshape 0 instead 50? And is your picture 16 or 32 colors? You're setting 4 bitplanes then setting 32 colors..

Colours are 16 - correct but as I am using sprites I need a 32 colour palette in the copper list hence the 16 colour screen and 32 colours in the Initcop command. I'm finally getting a handle on this sprite thing! Everyone should use them as you can have 16 colours independent of your main game colours which doubles your colours for no effort...

[carrion]

Do you have End command at the end of source code?
You always have to end your code with statement:

End

[Havie]

Originally Posted by carrion

Do you have End command at the end of source code?
You always have to end your code with statement:

End

Yes - there was an End. The issue was trying to use too big a shape. Loading straight to the screen sorted it.