Consideration of aspect ratio

simulator/src/main.rs

@@ -22,6 +22,12 @@ pub async fn run() {
     let _ = event_loop.run_app(&mut window_state);
 }
 
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+struct Globals {
+    aspect_ratio: f32,
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 enum Shape {
     Polygon,
@@ -64,7 +70,7 @@ struct InstanceRaw {
 impl InstanceRaw {
     fn desc() -> wgpu::VertexBufferLayout<'static> {
         wgpu::VertexBufferLayout {
-            array_stride: std::mem::size_of::<InstanceRaw>() as wgpu::BufferAddress,
+            array_stride: size_of::<InstanceRaw>() as wgpu::BufferAddress,
             step_mode: wgpu::VertexStepMode::Instance,
             attributes: &[
                 wgpu::VertexAttribute { offset: 0, shader_location: 5, format: wgpu::VertexFormat::Float32x4 },
@@ -183,6 +189,8 @@ struct State<'a> {
     instance_buffer: wgpu::Buffer,
 
     geometries: HashMap<Shape, Geometry>,
+    global_bind_group: wgpu::BindGroup,
+    global_buffer: wgpu::Buffer,
 
     simulator: Arc<RwLock<Simulator>>,
 }
@@ -199,7 +207,37 @@ impl<'a> State<'a> {
         let config = Self::create_surface_config(size, surface_caps);
         surface.configure(&device, &config);
 
-        let render_pipeline = Self::create_render_pipeline(&device, &config);
+        let globals = Globals {
+            aspect_ratio: config.width as f32 / config.height as f32,
+        };
+        let global_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("Global Uniform Buffer"),
+            contents: bytemuck::cast_slice(&[globals]),
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+        });
+        let global_bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("Global Bind Group Layout"),
+            entries: &[wgpu::BindGroupLayoutEntry {
+                binding: 0,
+                visibility: wgpu::ShaderStages::VERTEX,
+                ty: wgpu::BindingType::Buffer {
+                    ty: wgpu::BufferBindingType::Uniform,
+                    has_dynamic_offset: false,
+                    min_binding_size: None,
+                },
+                count: None,
+            }],
+        });
+        let global_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            layout: &global_bind_group_layout,
+            entries: &[wgpu::BindGroupEntry {
+                binding: 0,
+                resource: global_buffer.as_entire_binding(),
+            }],
+            label: Some("Global Bind Group"),
+        });
+
+        let render_pipeline = Self::create_render_pipeline(&device, &config, &global_bind_group_layout);
 
         let mut geometries = HashMap::new();
         let polygon_vertices = vec![
@@ -307,6 +345,9 @@ impl<'a> State<'a> {
             size,
             window: window_arc,
             
+            global_bind_group,
+            global_buffer,
+
             render_pipeline,
             geometries,
 
@@ -342,7 +383,7 @@ impl<'a> State<'a> {
         self.instances = updated_instances;
     }
     
-    fn create_render_pipeline(device: &Device, config: &wgpu::SurfaceConfiguration) -> wgpu::RenderPipeline {
+    fn create_render_pipeline(device: &Device, config: &wgpu::SurfaceConfiguration, global_bind_group_layout: &wgpu::BindGroupLayout) -> wgpu::RenderPipeline {
         let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
             label: Some("Shader"),
             source: wgpu::ShaderSource::Wgsl(include_str!("shader.wgsl").into()),
@@ -351,7 +392,7 @@ impl<'a> State<'a> {
         let render_pipeline_layout =
             device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                 label: Some("Render Pipeline Layout"),
-                bind_group_layouts: &[],
+                bind_group_layouts: &[&global_bind_group_layout],
                 push_constant_ranges: &[],
             });
 
@@ -451,6 +492,11 @@ impl<'a> State<'a> {
 
         self.surface.configure(&self.device, &self.config);
 
+        let new_globals = Globals {
+            aspect_ratio: self.config.width as f32 / self.config.height as f32,
+        };
+        self.queue.write_buffer(&self.global_buffer, 0, bytemuck::cast_slice(&[new_globals]));
+
         println!("Resized to {:?} from state!", new_size);
     }
 
@@ -484,6 +530,7 @@ impl<'a> State<'a> {
             });
 
             render_pass.set_pipeline(&self.render_pipeline);
+            render_pass.set_bind_group(0, &self.global_bind_group, &[]);
 
             for shape in [Shape::Polygon, Shape::Circle] {
                 let geometry = &self.geometries[&shape];

simulator/src/shader.wgsl

@@ -16,6 +16,13 @@ struct VSOutput {
     @location(0) color: vec3<f32>,
 };
 
+struct Globals {
+    aspect_ratio: f32,
+}
+
+@group(0) @binding(0)
+var<uniform> globals: Globals;
+
 @vertex
 fn vs_main(vertex: VertexInput, instance: InstanceInput) -> VSOutput {
     var out: VSOutput;
@@ -25,7 +32,14 @@ fn vs_main(vertex: VertexInput, instance: InstanceInput) -> VSOutput {
         instance.model_row2,
         instance.model_row3
     );
-    out.position = model * vec4<f32>(vertex.position, 1.0);
+
+    let projection = mat4x4<f32>(
+        vec4<f32>(1.0 / globals.aspect_ratio, 0.0, 0.0, 0.0),
+        vec4<f32>(0.0, 1.0, 0.0, 0.0),
+        vec4<f32>(0.0, 0.0, 1.0, 0.0),
+        vec4<f32>(0.0, 0.0, 0.0, 1.0),
+    );
+    out.position = projection * model * vec4<f32>(vertex.position, 1.0);
     out.color = instance.color;
     return out;
 }