English Amiga Board - View Single Post - Blitter fill, writing clearing instead of setting?

deimos · 16 December 2019, 14:56

Is the blitter fill mode limited to setting bits only? I can't find, either by searching or experimentation any way to clear rather than setting, just indications that it's not possible.

I want to fill / clear this (simplified):

00100
00010
00001
00000
00000

to result in:

00111
00011
00001
00000
00000

I can add extra 1s to the source if I have to, but I can't change where the existing 1s are.

This is for clearing / filling the last bitplane in my flight sim thingy to make sure the ground is drawn before I draw things on top of it. I need it to be inclusively filled so it's consistent with how it's drawn in other situations and so it works when I draw the next layer on top by drawing on another bitplane.

Any ideas?

16 December 2019, 14:56	#1
deimos It's coming back! Join Date: Jul 2018 Location: comp.sys.amiga Posts: 762	Blitter fill, writing clearing instead of setting? Is the blitter fill mode limited to setting bits only? I can't find, either by searching or experimentation any way to clear rather than setting, just indications that it's not possible. I want to fill / clear this (simplified): 00100 00010 00001 00000 00000 to result in: 00111 00011 00001 00000 00000 I can add extra 1s to the source if I have to, but I can't change where the existing 1s are. This is for clearing / filling the last bitplane in my flight sim thingy to make sure the ground is drawn before I draw things on top of it. I need it to be inclusively filled so it's consistent with how it's drawn in other situations and so it works when I draw the next layer on top by drawing on another bitplane. Any ideas? Last edited by deimos; 16 December 2019 at 15:06.