背景画像の描画に対応 (#71)

* 背景に対応した気がする

* とりあえずの実装。透過の効いた書き込みができていない

* 色々わからなくなってきたからいったんここでコミット

* fix document

* fix clippy

* rename pipeline name

* swap method position

* fix example

* 背景画像の変更。細かい挙動に謎はあるが一旦これで完成。

font_rasterizer/Cargo.toml

@@ -16,6 +16,7 @@ wgpu = { workspace = true }
 winit = { workspace = true }
 bitflags = { workspace = true }
 rand = { workspace = true }
+image ={ workspace = true}
 
 rustybuzz.workspace = true
 cgmath.workspace = true

font_rasterizer/src/background_bind_group.rs

@@ -0,0 +1,54 @@
+use crate::screen_texture::BackgroundImageTexture;
+
+/// BackgroundImage用の BindGroup。
+pub struct BackgroundImageBindGroup {
+    pub(crate) layout: wgpu::BindGroupLayout,
+}
+
+impl BackgroundImageBindGroup {
+    pub(crate) fn new(device: &wgpu::Device) -> Self {
+        let layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            entries: &[
+                wgpu::BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Texture {
+                        multisampled: false,
+                        view_dimension: wgpu::TextureViewDimension::D2,
+                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                    },
+                    count: None,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                    count: None,
+                },
+            ],
+            label: Some("Background Image Bind Group Layout"),
+        });
+        Self { layout }
+    }
+
+    pub fn to_bind_group(
+        &self,
+        device: &wgpu::Device,
+        background_image_texture: &BackgroundImageTexture,
+    ) -> wgpu::BindGroup {
+        device.create_bind_group(&wgpu::BindGroupDescriptor {
+            layout: &self.layout,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: wgpu::BindingResource::TextureView(&background_image_texture.view),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::Sampler(&background_image_texture.sampler),
+                },
+            ],
+            label: Some("Background Image Bind Group"),
+        })
+    }
+}

font_rasterizer/src/lib.rs

@@ -1,3 +1,4 @@
+mod background_bind_group;
 pub mod char_width_calcurator;
 pub mod color_theme;
 pub mod context;