Search found 55 matches

by Maziac
Sun Sep 09, 2018 11:01 am
Forum: Software
Topic: Sprite mirroring, rotation
Replies: 0
Views: 1560

Sprite mirroring, rotation

Hi,

The 'Sprite Attribute Upload' has 3 bits for x, y- mirroring and rotation.
What is the order in which those are executed?
Is it mirrored first then rotated?
Or first rotated and then mirrored?
by Maziac
Fri Sep 07, 2018 4:30 pm
Forum: Software
Topic: PIXELAD/PIXELDN
Replies: 4
Views: 754

PIXELAD/PIXELDN

Hi,
a question about these 2 new instructions:
What will happen if the y-coordinate is bigger than 191?
I.e. what result is stored in HL if I use
LD E,0
LD D,192
PIXELAD

Similar question for PIXELDN:
What will be the result if HL is already in the last (y=191) line?
by Maziac
Wed Sep 05, 2018 7:37 pm
Forum: Software
Topic: Sprite palette offset
Replies: 9
Views: 8165

Re: Sprite palette offset

@Cesar: Just tested your last commit: works excellent with your fix now.
by Maziac
Wed Sep 05, 2018 7:01 pm
Forum: Software
Topic: Sprite palette offset
Replies: 9
Views: 8165

Re: Sprite palette offset

Thanks.
by Maziac
Wed Sep 05, 2018 4:05 pm
Forum: Software
Topic: Memory bank switching improvement
Replies: 1
Views: 424

Memory bank switching improvement

I was wondering if there exist ideas to improve the memory switching in the future. Currently the bank switching switches all accesses at the same time, i.e. READ, WRITE and OPCODE fetch. It would beneficial to have an independent memory bank switching for any of those accesses. I.e. it can simplify...
by Maziac
Wed Sep 05, 2018 3:41 pm
Forum: Software
Topic: Sprite palette offset
Replies: 9
Views: 8165

Re: Sprite palette offset

That is interesting.

What about the palette offset? Is that added as well if the original color index in the sprite pattern is the transparency color index?

And what happens if the resulting index would become >= 256? Is it simply masked with 0xFF?
by Maziac
Mon Sep 03, 2018 7:32 pm
Forum: Software
Topic: Sprite Attribute Upload
Replies: 5
Views: 624

Re: Sprite Attribute Upload

OK, so it seems a redundant storage in the ZX Spectrum RAM is required.
That's a pity.
by Maziac
Mon Sep 03, 2018 7:29 pm
Forum: Software
Topic: Sprite palette offset
Replies: 9
Views: 8165

Sprite palette offset

If I use a palette offset as attribute in byte 3 of the Sprite Attributes what happens to the sprite transparency color. Will the offset be added to that as well? I.e. it's not so clear to me if the transparency color is an index to the color or the color itself. It would make sense if it would be a...
by Maziac
Mon Sep 03, 2018 6:42 pm
Forum: Software
Topic: Sprite Attribute Upload
Replies: 5
Views: 624

Sprite Attribute Upload

Another question: Is it possible to access the sprite attributes also individually. According the documentation (wiki) there are 4 bytes that can be written by writing to port 0x57. byte 0: X-pos byte 1: Y-pos byte 2: Palette offset etc byte 3: Visibility + pattern index etc. Is it possible to acces...
by Maziac
Mon Sep 03, 2018 5:50 pm
Forum: Software
Topic: Copper program - one scanline
Replies: 4
Views: 523

Re: Copper program - one scanline

For sure!