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use bevy::{
prelude::*,
render::{
render_asset::RenderAssetUsages,
render_resource::{Extent3d, TextureDimension, TextureFormat, TextureUsages}, extract_component::ExtractComponent,
},
};
#[derive(Component, ExtractComponent, Clone)]
pub struct DitherPostProcessSettings(Handle<Image>);
impl DitherPostProcessSettings {
pub fn new(level: u32, mut images: ResMut<Assets<Image>>) -> Self {
let power = level + 1;
let map_size: u32 = 1 << power;
let mut buffer = Vec::<u8>::new();
for row in 0..map_size {
for col in 0..map_size {
let a = row ^ col;
// Interleave bits of `a` with bits of y coordinate in reverse order
let mut result: u64 = 0;
let mut bit = 0;
let mut mask = power as i32 - 1;
loop {
if bit >= 2 * power {
break;
}
result |= (((col >> mask) & 1) << bit) as u64;
bit += 1;
result |= (((a >> mask) & 1) << bit) as u64;
bit += 1;
mask -= 1;
}
let value = ((result as f32 / map_size.pow(2) as f32) * 255.0) as u8;
buffer.push(value);
}
}
let mut image = Image::new(
Extent3d {
width: map_size,
height: map_size,
depth_or_array_layers: 1,
},
TextureDimension::D2,
buffer,
TextureFormat::R8Unorm,
RenderAssetUsages::RENDER_WORLD,
);
image.texture_descriptor.usage =
TextureUsages::COPY_DST | TextureUsages::STORAGE_BINDING | TextureUsages::TEXTURE_BINDING;
let handle = images.add(image);
Self(handle)
}
pub fn handle(&self) -> Handle<Image> {
self.0.clone()
}
}
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