Looking near the bottom where the horizontal purple meets the grey and also the bottom left corner of the green and black it almost looks like there is a y flipping being done.
You could try reversing the order of the colums (I guess y is choosing columns) in the de-dithering matrix.
Search found 6 matches
- Thu 14 Jun, 2018 12:21 am
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
- Thu 14 Jun, 2018 12:12 am
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
Re: [Patch] 3dfx rendering accuracy
Could you try changing the:
rb += 4;
g += 2;
To:
rb += 0;
g += 0;
and also:
rb += 8;
g += 4;
That should move around the centering of the dithering.
rb += 4;
g += 2;
To:
rb += 0;
g += 0;
and also:
rb += 8;
g += 4;
That should move around the centering of the dithering.
- Wed 13 Jun, 2018 2:48 pm
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
Re: [Patch] 3dfx rendering accuracy
Yeah that definitely doesn't seem right. I have attached a dither subtraction routine that I think better balances the dither removal. I have changed your indexing to use col selection by x and row selection by y. The result using this routine is: The rb (5 bit) 0 value returns values from -3 to 4 b...
- Tue 12 Jun, 2018 9:10 pm
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
Re: [Patch] 3dfx rendering accuracy
Interesting, the formula I gave causes overflow for rb values of 255 (when RGB565 rb =31) but otherwise works out.
- Tue 12 Jun, 2018 8:18 pm
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
Re: [Patch] 3dfx rendering accuracy
So I think in your code you want the following: // Dither subtract value drb= ((int)(15 - dither_matrix_4x4[((y)<<2) + x])>>1); dg= ((int)(15 - dither_matrix_4x4[((y)<<2) + x])>>2); // Add subtract value rb = i + drb; Seems counter intuitive to add the subtract value but I think the math works out. ...
- Tue 12 Jun, 2018 3:53 pm
- Forum: Patches
- Topic: [Patch] 3dfx rendering accuracy
- Replies: 20
- Views: 30781
Re: [Patch] 3dfx rendering accuracy
I'm not sure how the current dither_rb/dither_g tables were generated, my dithersub table can't seem to match it, and not even basing the generation off the old dither generation function from years ago can match it I would guess you are missing the conversion to RGB565 that is done after the dithe...