Graphical glitch - NESdev BBS

Graphical glitch
by bigrob on 2007-02-18 (#22010)

I'm having a problem with my emulator that I'm finding hard to fix... A picture's worth a thousand words, so here's what the Mario sprite looks like.

All sprites in the game have the same problem - any tips on what could be wrong? All games I've tried display this issue, although they play fine.

Thanks

by tepples on 2007-02-18 (#22013)

Does it screw up when he faces both directions or just that one?

by bigrob on 2007-02-18 (#22014)

Both directions, and ALL sprites are affected... I've looked over my code again, but I can't spot the problem. I was hoping this was a commonly seen problem or something

Thanks for the reply.

by Bregalad on 2007-02-18 (#22016)

Maybe your handling for 8x16 sprites is incorrect ?

by tepples on 2007-02-18 (#22018)

SMB1 is 8x8.

by WedNESday on 2007-02-18 (#22021)

Looks like tile fetching is incorrect. If you look closely, you can see that the weird colours around Mario, are actual tiles that have been fetched incorrectly. Yes, Super Mario Bros. is 8x8 only. Yeah, it is really common to see such a thing when writing your emulator, we've all been there.

Nice palette btw, where did you get it?

by Zepper on 2007-02-18 (#22026)

WedNESday wrote:
Looks like tile fetching is incorrect. If you look closely, you can see that the weird colours around Mario, are actual tiles that have been fetched incorrectly.

Nope, it's the wrong sprite horizontal flipping.

by bigrob on 2007-02-19 (#22054)

Fx3 wrote:
WedNESday wrote:
Looks like tile fetching is incorrect. If you look closely, you can see that the weird colours around Mario, are actual tiles that have been fetched incorrectly.

Nope, it's the wrong sprite horizontal flipping.

If there was a prize to be won, WedNESday would get it - I was screwing up the byte order in my tile fetching code I'm not sure how I managed it yet, but it's fixed now and working great. Time to add sound support!

Thanks guys.

Oh, and I don't remember exactly where I stole the palette from... Some other emulator anyway, it's not my own work.

by Zepper on 2007-02-19 (#22055)

bigrob wrote:
If there was a prize to be won, WedNESday would get it - I was screwing up the byte order in my tile fetching code I'm not sure how I managed it yet, but it's fixed now and working great.

Fine. Two guesses.
Glad you fixed it.

by WedNESday on 2007-02-20 (#22073)

Fx3 wrote:
bigrob wrote:
If there was a prize to be won, WedNESday would get it - I was screwing up the byte order in my tile fetching code I'm not sure how I managed it yet, but it's fixed now and working great.

Fine. Two guesses.
Glad you fixed it.