| 1 | /*************************************************************************** |
| 2 | * Copyright (C) 2016 PCSX4ALL Team * |
| 3 | * * |
| 4 | * This program is free software; you can redistribute it and/or modify * |
| 5 | * it under the terms of the GNU General Public License as published by * |
| 6 | * the Free Software Foundation; either version 2 of the License, or * |
| 7 | * (at your option) any later version. * |
| 8 | * * |
| 9 | * This program is distributed in the hope that it will be useful, * |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of * |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
| 12 | * GNU General Public License for more details. * |
| 13 | * * |
| 14 | * You should have received a copy of the GNU General Public License * |
| 15 | * along with this program; if not, write to the * |
| 16 | * Free Software Foundation, Inc., * |
| 17 | * 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307 USA. * |
| 18 | ***************************************************************************/ |
| 19 | |
| 20 | #ifndef _OP_DITHER_H_ |
| 21 | #define _OP_DITHER_H_ |
| 22 | |
| 23 | static void SetupDitheringConstants() |
| 24 | { |
| 25 | // Initialize Dithering Constants |
| 26 | // The screen is divided into 8x8 chunks and sub-unitary noise is applied |
| 27 | // using the following matrix. This ensures that data lost in color |
| 28 | // quantization will be added back to the image 'by chance' in predictable |
| 29 | // patterns that are naturally 'smoothed' by your sight when viewed from a |
| 30 | // certain distance. |
| 31 | // |
| 32 | // http://caca.zoy.org/study/index.html |
| 33 | // |
| 34 | // Shading colors are encoded in 4.5, and then are quantitized to 5.0, |
| 35 | // DitherMatrix constants reflect that. |
| 36 | |
| 37 | static const u8 DitherMatrix[] = { |
| 38 | 0, 32, 8, 40, 2, 34, 10, 42, |
| 39 | 48, 16, 56, 24, 50, 18, 58, 26, |
| 40 | 12, 44, 4, 36, 14, 46, 6, 38, |
| 41 | 60, 28, 52, 20, 62, 30, 54, 22, |
| 42 | 3, 35, 11, 43, 1, 33, 9, 41, |
| 43 | 51, 19, 59, 27, 49, 17, 57, 25, |
| 44 | 15, 47, 7, 39, 13, 45, 5, 37, |
| 45 | 63, 31, 55, 23, 61, 29, 53, 21 |
| 46 | }; |
| 47 | |
| 48 | int i, j; |
| 49 | for (i = 0; i < 8; i++) |
| 50 | { |
| 51 | for (j = 0; j < 8; j++) |
| 52 | { |
| 53 | u16 offset = (i << 3) | j; |
| 54 | |
| 55 | u32 component = ((DitherMatrix[offset] + 1) << 4) / 65; //[5.5] -> [5] |
| 56 | |
| 57 | // XXX - senquack - hack Dec 2016 |
| 58 | // Until JohnnyF gets the time to work further on dithering, |
| 59 | // force lower bit of component to 0. This fixes grid pattern |
| 60 | // affecting quality of dithered image, as well as loss of |
| 61 | // detail in dark areas. With lower bit unset like this, existing |
| 62 | // 27-bit accuracy of dithering math is unneeded, could be 24-bit. |
| 63 | // Is 8x8 matrix overkill as a result, can we use 4x4? |
| 64 | component &= ~1; |
| 65 | |
| 66 | gpu_unai.DitherMatrix[offset] = (component) |
| 67 | | (component << 10) |
| 68 | | (component << 20); |
| 69 | } |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | //////////////////////////////////////////////////////////////////////////////// |
| 74 | // Convert padded u32 5.4:5.4:5.4 bgr fixed-pt triplet to final bgr555 color, |
| 75 | // applying dithering if specified by template parameter. |
| 76 | // |
| 77 | // INPUT: |
| 78 | // 'uSrc24' input: 000bbbbbXXXX0gggggXXXX0rrrrrXXXX |
| 79 | // ^ bit 31 |
| 80 | // 'pDst' is a pointer to destination framebuffer pixel, used |
| 81 | // to determine which DitherMatrix[] entry to apply. |
| 82 | // RETURNS: |
| 83 | // u16 output: 0bbbbbgggggrrrrr |
| 84 | // ^ bit 16 |
| 85 | // Where 'X' are fixed-pt bits, '0' is zero-padding, and '-' is don't care |
| 86 | //////////////////////////////////////////////////////////////////////////////// |
| 87 | template <int DITHER> |
| 88 | GPU_INLINE u16 gpuColorQuantization24(u32 uSrc24, const le16_t *pDst) |
| 89 | { |
| 90 | if (DITHER) |
| 91 | { |
| 92 | uintptr_t fbpos = pDst - gpu_unai.vram; |
| 93 | u16 offset = ((fbpos & (0x7 << 10)) >> 7) | (fbpos & 0x7); |
| 94 | |
| 95 | //clean overflow flags and add |
| 96 | uSrc24 = (uSrc24 & 0x1FF7FDFF) + gpu_unai.DitherMatrix[offset]; |
| 97 | |
| 98 | if (uSrc24 & (1<< 9)) uSrc24 |= (0x1FF ); |
| 99 | if (uSrc24 & (1<<19)) uSrc24 |= (0x1FF<<10); |
| 100 | if (uSrc24 & (1<<29)) uSrc24 |= (0x1FF<<20); |
| 101 | } |
| 102 | |
| 103 | return ((uSrc24>> 4) & (0x1F )) |
| 104 | | ((uSrc24>> 9) & (0x1F<<5 )) |
| 105 | | ((uSrc24>>14) & (0x1F<<10)); |
| 106 | } |
| 107 | |
| 108 | #endif //_OP_DITHER_H_ |