From f98b27592b2482dc89adc055073a3ee015f2424e Mon Sep 17 00:00:00 2001
From: Silas Bartha <silas@exvacuum.dev>
Date: Wed, 24 Apr 2024 14:03:15 -0400
Subject: Initial Commit

---
 src/components.rs | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 src/components.rs

(limited to 'src/components.rs')

diff --git a/src/components.rs b/src/components.rs
new file mode 100644
index 0000000..932aac3
--- /dev/null
+++ b/src/components.rs
@@ -0,0 +1,63 @@
+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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