Use more accurate color ramp conversion method

stinkhead7ds
Ashley N. 2023-09-18 23:42:58 -04:00
parent c4af44a5e4
commit 0dc7e95c21
1 changed files with 34 additions and 4 deletions

View File

@ -1,15 +1,45 @@
use crate::reskit::utility; use crate::reskit::utility;
use std::error::Error; use std::{error::Error, ops::RangeInclusive};
use std::fs; use std::fs;
use std::fs::File; use std::fs::File;
use std::io::Write; use std::io::Write;
use image::{ GenericImageView, DynamicImage }; use image::{ GenericImageView, DynamicImage };
/**
* Get a particular RGB component adjusted for the Mega Drive VDP colour ramp.
* See colour ramp at https://plutiedev.com/vdp-color-ramp
*/
fn rgb_component_to_ramp( component: u16 ) -> Result<u16, Box<dyn Error>> {
let ramp: [(RangeInclusive<u16>, (u16,u16)); 7] = [
(0..=52, (0x0, 0x2)),
(52..=87, (0x2, 0x4)),
(87..=116, (0x4, 0x6)),
(116..=144, (0x6, 0x8)),
(144..=172, (0x8, 0xA)),
(172..=206, (0xA, 0xC)),
(206..=255, (0xC, 0xE))
];
for i in 0..ramp.len() {
let ( ramp_range, ( cram_round_down, cram_round_up ) ) = &ramp[ i ];
if ramp_range.contains( &component ) {
let range_midpoint = ramp_range.start() + ( ( ramp_range.end() - ramp_range.start() ) / 2 );
return if component >= range_midpoint {
Ok( *cram_round_up )
} else {
Ok( *cram_round_down )
}
}
}
Err( "rgb component not in range 0-255" )?
}
pub fn color_to_palette( r: u16, g: u16, b: u16, palette: &mut [u16; 16] ) -> Result<u32, Box<dyn Error>> { pub fn color_to_palette( r: u16, g: u16, b: u16, palette: &mut [u16; 16] ) -> Result<u32, Box<dyn Error>> {
let final_val = let final_val =
( ( r & 0x00F0 ) >> 4 ) | ( rgb_component_to_ramp( b )? << 8 ) |
( g & 0x00F0 ) | ( rgb_component_to_ramp( g )? << 4 ) |
( ( b & 0x00F0 ) << 4 ); ( rgb_component_to_ramp( r )? );
// Does the color already exist? // Does the color already exist?
for i in 0..palette.len() { for i in 0..palette.len() {