restore pixelate shader

assets/shaders/pixelate.wgsl

@@ -0,0 +1,29 @@
+#import bevy_pbr::utils
+#import bevy_core_pipeline::fullscreen_vertex_shader FullscreenVertexOutput
+
+@group(0) @binding(0) var screen_texture: texture_2d<f32>;
+@group(0) @binding(1) var texture_sampler: sampler;
+
+struct PixelateSettings {
+    block_size: f32,
+#ifdef SIXTEEN_BYTE_ALIGNMENT
+    // WebGL2 structs must be 16 byte aligned.
+    _webgl2_padding: vec3<f32>
+#endif
+}
+@group(0) @binding(2) var<uniform> settings: PixelateSettings;
+
+@fragment
+fn fragment(in: FullscreenVertexOutput) -> @location(0) vec4<f32> {
+    let resolution = vec2<f32>(textureDimensions(screen_texture));
+
+    let width_height_over_block_size = resolution / max(1.0, settings.block_size);
+
+    var uv = in.uv + 0.5;
+    uv *= width_height_over_block_size;
+    uv = floor(uv);
+    uv /= width_height_over_block_size;
+    uv -= 0.5;
+
+    return textureSample(screen_texture, texture_sampler, uv);
+}