add first version of fast crt shader

uw8-window/src/gpu/fast_crt.rs

@@ -0,0 +1,157 @@
+use wgpu::util::DeviceExt;
+use winit::dpi::PhysicalSize;
+
+use super::Filter;
+
+pub struct FastCrtFilter {
+    uniform_buffer: wgpu::Buffer,
+    bind_group: wgpu::BindGroup,
+    pipeline: wgpu::RenderPipeline,
+}
+
+impl FastCrtFilter {
+    pub fn new(
+        device: &wgpu::Device,
+        screen: &wgpu::TextureView,
+        resolution: PhysicalSize<u32>,
+        surface_format: wgpu::TextureFormat,
+    ) -> FastCrtFilter {
+        let uniforms = Uniforms {
+            texture_scale: texture_scale_from_resolution(resolution),
+        };
+
+        let uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: None,
+            contents: bytemuck::cast_slice(&[uniforms]),
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+        });
+
+        let bind_group_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,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 2,
+                    visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
+                    ty: wgpu::BindingType::Buffer {
+                        ty: wgpu::BufferBindingType::Uniform,
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                },
+            ],
+            label: None,
+        });
+
+        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
+            mag_filter: wgpu::FilterMode::Linear,
+            ..Default::default()
+        });
+
+        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            layout: &bind_group_layout,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: wgpu::BindingResource::TextureView(&screen),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 1,
+                    resource: wgpu::BindingResource::Sampler(&sampler),
+                },
+                wgpu::BindGroupEntry {
+                    binding: 2,
+                    resource: uniform_buffer.as_entire_binding(),
+                },
+            ],
+            label: None,
+        });
+
+        let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+            label: None,
+            source: wgpu::ShaderSource::Wgsl(include_str!("fast_crt.wgsl").into()),
+        });
+
+        let render_pipeline_layout =
+            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+                label: None,
+                bind_group_layouts: &[&bind_group_layout],
+                push_constant_ranges: &[],
+            });
+
+        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: None,
+            layout: Some(&render_pipeline_layout),
+            vertex: wgpu::VertexState {
+                module: &shader,
+                entry_point: "vs_main",
+                buffers: &[],
+            },
+            fragment: Some(wgpu::FragmentState {
+                module: &shader,
+                entry_point: "fs_main",
+                targets: &[Some(wgpu::ColorTargetState {
+                    format: surface_format,
+                    blend: None,
+                    write_mask: wgpu::ColorWrites::ALL,
+                })],
+            }),
+            primitive: Default::default(),
+            depth_stencil: None,
+            multisample: Default::default(),
+            multiview: None,
+        });
+
+        FastCrtFilter {
+            uniform_buffer,
+            bind_group,
+            pipeline: render_pipeline,
+        }
+    }
+}
+
+impl Filter for FastCrtFilter {
+    fn resize(&self, queue: &wgpu::Queue, new_size: PhysicalSize<u32>) {
+        let uniforms = Uniforms {
+            texture_scale: texture_scale_from_resolution(new_size),
+        };
+        queue.write_buffer(&self.uniform_buffer, 0, bytemuck::cast_slice(&[uniforms]));
+    }
+
+    fn render<'a>(&'a self, render_pass: &mut wgpu::RenderPass<'a>) {
+        render_pass.set_pipeline(&self.pipeline);
+        render_pass.set_bind_group(0, &self.bind_group, &[]);
+        render_pass.draw(0..6, 0..1);
+    }
+}
+
+fn texture_scale_from_resolution(res: PhysicalSize<u32>) -> [f32; 4] {
+    let scale = ((res.width as f32) / 160.0).min((res.height as f32) / 120.0);
+    [
+        scale / res.width as f32,
+        scale / res.height as f32,
+        2.0 / scale,
+        0.0,
+    ]
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+struct Uniforms {
+    texture_scale: [f32; 4],
+}

uw8-window/src/gpu/fast_crt.wgsl

@@ -0,0 +1,46 @@
+struct VertexOutput {
+    @builtin(position) clip_position: vec4<f32>,
+    @location(0) tex_coords: vec2<f32>,
+}
+
+struct Uniforms {
+    texture_scale: vec4<f32>,
+}
+
+@group(0) @binding(2) var<uniform> uniforms: Uniforms;
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) in_vertex_index: u32,
+) -> VertexOutput {
+    var out: VertexOutput;
+    let i = in_vertex_index / 3u + in_vertex_index % 3u;
+    let x = 0.0 + f32(i % 2u) * 320.0;
+    let y = 0.0 + f32(i / 2u) * 240.0;
+    out.clip_position = vec4<f32>((vec2<f32>(x, y) - vec2<f32>(160.0, 120.0)) * uniforms.texture_scale.xy, 0.0, 1.0);
+    out.tex_coords = vec2<f32>(x, y);
+    return out;
+}
+
+@group(0) @binding(0) var screen_texture: texture_2d<f32>;
+@group(0) @binding(1) var linear_sampler: sampler;
+
+fn row_factor(offset: f32) -> f32 {
+    return 1.0 / (1.0 + offset * offset * 16.0);
+}
+
+@fragment
+fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
+    let base = round(in.tex_coords) - vec2<f32>(0.5);
+    let frac = in.tex_coords - base;
+    
+    let top_factor = row_factor(frac.y);
+    let bottom_factor = row_factor(frac.y - 1.0);
+    
+    let v = base.y + bottom_factor / (bottom_factor + top_factor);
+    
+    let u = in.tex_coords.x;
+    
+    return textureSample(screen_texture, linear_sampler, vec2<f32>(u, v) / vec2<f32>(320.0, 240.0)) * (top_factor + bottom_factor) * 2.0;
+}
+

uw8-window/src/gpu/mod.rs

@@ -17,9 +17,11 @@ use winit::platform::unix::EventLoopExtUnix;
 use winit::platform::windows::EventLoopExtWindows;
 
 mod crt;
+mod fast_crt;
 mod square;
 
 use crt::CrtFilter;
+use fast_crt::FastCrtFilter;
 use square::SquareFilter;
 
 pub struct Window {
@@ -155,6 +157,14 @@ impl Window {
                                     ))
                                 }
                                 Some(VirtualKeyCode::Key2) => {
+                                    filter = Box::new(FastCrtFilter::new(
+                                        &device,
+                                        &palette_screen_mode.screen_view,
+                                        window.inner_size(),
+                                        surface_config.format,
+                                    ))
+                                }
+                                Some(VirtualKeyCode::Key3) => {
                                     filter = Box::new(CrtFilter::new(
                                         &device,
                                         &palette_screen_mode.screen_view,

uw8-window/src/gpu/square.wgsl

@@ -15,8 +15,8 @@ fn vs_main(
 ) -> VertexOutput {
     var out: VertexOutput;
     let i = in_vertex_index / 3u + in_vertex_index % 3u;
-    let x = -1.0 + f32(i % 2u) * 322.0;
-    let y = -1.0 + f32(i / 2u) * 242.0;
+    let x = 0.0 + f32(i % 2u) * 320.0;
+    let y = 0.0 + f32(i / 2u) * 240.0;
     out.clip_position = vec4<f32>((vec2<f32>(x, y) - vec2<f32>(160.0, 120.0)) * uniforms.texture_scale.xy, 0.0, 1.0);
     out.tex_coords = vec2<f32>(x, y);
     return out;