mirror of
https://github.com/gbdev/rgbds.git
synced 2025-11-20 10:12:06 +00:00
73 lines
2.7 KiB
C++
73 lines
2.7 KiB
C++
// SPDX-License-Identifier: MIT
|
|
|
|
#include "gfx/rgba.hpp"
|
|
|
|
#include <algorithm>
|
|
#include <math.h>
|
|
#include <stdint.h>
|
|
|
|
#include "helpers.hpp" // assume
|
|
|
|
#include "gfx/main.hpp" // options
|
|
|
|
// Based on inverting the "Modern - Accurate" formula used by SameBoy
|
|
// since commit b5a611c5db46d6a0649d04d24d8d6339200f9ca1 (Dec 2020),
|
|
// with gaps in the scale curve filled by polynomial interpolation.
|
|
// clang-format off: vertically align columns of values
|
|
static std::array<uint8_t, 256> reverse_curve{
|
|
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1,
|
|
1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3,
|
|
3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5,
|
|
5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7,
|
|
7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 10, 10, 10, 10,
|
|
10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13,
|
|
13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 16, 16, 16,
|
|
16, 16, 16, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 19, 19,
|
|
19, 19, 19, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 22,
|
|
22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24,
|
|
24, 24, 24, 25, 25, 25, 25, 25, 25, 25, 25, 26, 26, 26, 26, 26,
|
|
26, 26, 26, 27, 27, 27, 27, 27, 27, 27, 27, 27, 28, 28, 28, 28,
|
|
28, 28, 28, 28, 28, 28, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29,
|
|
29, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30,
|
|
31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31,
|
|
31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31,
|
|
};
|
|
// clang-format on
|
|
|
|
uint16_t Rgba::cgbColor() const {
|
|
if (isTransparent()) {
|
|
return transparent;
|
|
}
|
|
assume(isOpaque());
|
|
|
|
uint8_t r = red, g = green, b = blue;
|
|
if (options.useColorCurve) {
|
|
double g_linear = pow(g / 255.0, 2.2), b_linear = pow(b / 255.0, 2.2);
|
|
double g_adjusted = std::clamp((g_linear * 4 - b_linear) / 3, 0.0, 1.0);
|
|
g = round(pow(g_adjusted, 1 / 2.2) * 255);
|
|
r = reverse_curve[r];
|
|
g = reverse_curve[g];
|
|
b = reverse_curve[b];
|
|
} else {
|
|
r >>= 3;
|
|
g >>= 3;
|
|
b >>= 3;
|
|
}
|
|
return r | g << 5 | b << 10;
|
|
}
|
|
|
|
uint8_t Rgba::grayIndex() const {
|
|
assume(isGray());
|
|
// 2bpp shades are inverted from RGB PNG; %00 = white, %11 = black
|
|
uint8_t gray = 255 - red;
|
|
if (options.palSpecType == Options::DMG) {
|
|
assume(!options.hasTransparentPixels);
|
|
// Reduce gray shade from 0..<256 to 0..<4, then map to color index,
|
|
// then reduce to 0..<nbColorsPerPal
|
|
return options.dmgColors[gray * 4 / 256] * options.nbColorsPerPal / 4;
|
|
}
|
|
// Reduce gray shade from 0..<256 to hasTransparentPixels..<nbColorsPerPal
|
|
// Note that `maxOpaqueColors()` already takes `hasTransparentPixels` into account
|
|
return gray * options.maxOpaqueColors() / 256 + options.hasTransparentPixels;
|
|
}
|