ref: 6df75f7af3ccd28ad2432460cacdf853edb1113d
dir: /src/gfx/rgba.cpp/
/*
* This file is part of RGBDS.
*
* Copyright (c) 2022, Eldred Habert and RGBDS contributors.
*
* SPDX-License-Identifier: MIT
*/
#include "gfx/rgba.hpp"
#include <assert.h>
#include <stdint.h>
#include "gfx/main.hpp" // options
/*
* based on the Gaussian-like curve used by SameBoy since commit
* 65dd02cc52f531dbbd3a7e6014e99d5b24e71a4c (Oct 2017)
* with ties resolved by comparing the difference of the squares.
*/
static std::array<uint8_t, 256> reverse_curve{
0, 0, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, // These
5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, // comments
7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, // prevent
9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, // clang-format
10, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, // from
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, // reflowing
13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, // these
14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, // sixteen
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, // 16-item
17, 17, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, // lines,
18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, // which,
19, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, // in
21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22, 22, // my
22, 23, 23, 23, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, // opinion,
24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26, 26, // help
26, 27, 27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 30, 30, 31, // visualization!
};
uint16_t Rgba::cgbColor() const {
if (isTransparent()) {
return transparent;
}
assert(isOpaque());
uint8_t r = red, g = green, b = blue;
if (options.useColorCurve) {
g = g * 4 < b ? 0 : (g * 4 - b) / 3;
r = reverse_curve[r];
g = reverse_curve[g];
b = reverse_curve[b];
}
return (r >> 3) | (g >> 3) << 5 | (b >> 3) << 10;
}
uint8_t Rgba::grayIndex() const {
assert(isGray());
// Convert from [0; 256[ to [0; maxOpaqueColors[
return static_cast<uint16_t>(255 - red) * options.maxOpaqueColors() / 256;
}