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add new_colored_luminance_map method

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Gered 2022-07-18 21:36:28 -04:00
parent 9cac8d2500
commit d6e05c7e3a
1 changed files with 35 additions and 0 deletions
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35
libretrogd/src/graphics/blendmap.rs
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@ -76,6 +76,41 @@ impl BlendMap {
blend_map
}
/// Creates and returns a new [`BlendMap`] which can be used to blend source colors together
/// with the destination using a colorization effect based on a function providing a custom
/// calculation combining the source and destination color luminance values to return a weight
/// into the gradient range given.
pub fn new_colored_luminance_map(
gradient_start: u8,
gradient_end: u8,
palette: &Palette,
f: impl Fn(f32, f32) -> f32
) -> BlendMap {
let (gradient_start, gradient_end) = if gradient_start > gradient_end {
(gradient_end, gradient_start)
} else {
(gradient_start, gradient_end)
};
let gradient_size = gradient_end - gradient_start + 1;
let mut blend_map = BlendMap::new(0, 255);
for source_color in 0..=255 {
let (r, g, b) = from_rgb32(palette[source_color]);
let source_luminance = luminance(r, g, b);
for dest_color in 0..=255 {
let (r, g, b) = from_rgb32(palette[dest_color]);
let destination_luminance = luminance(r, g, b);
let weight = (f(source_luminance, destination_luminance) * 255.0) as u8;
blend_map.set_mapping(
source_color,
dest_color,
(gradient_size - 1).wrapping_sub(weight / (256 / gradient_size as u32) as u8) + gradient_start
).unwrap();
}
}
blend_map
}
/// Creates and returns a new [`BlendMap`] which can be used to blend all 256 colors together
/// with every other color, weighting the blending based on the ratios given where 0.0 will
/// result in that component being totally transparent and 1.0, totally opaque.