From d613b20803f41eeb4f6ae27003d5bfa371502930 Mon Sep 17 00:00:00 2001
From: Micha White <botahamec@outlook.com>
Date: Sun, 18 Sep 2022 15:30:56 -0400
Subject: Created a vertex buffer

---
 src/lib.rs      |  2 ++
 src/renderer.rs | 28 +++++++++++++++++++++++-----
 src/vertex.rs   | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 5 deletions(-)
 create mode 100644 src/vertex.rs

(limited to 'src')

diff --git a/src/lib.rs b/src/lib.rs
index 1bdc5f6..fbc517b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,8 @@
 
 pub mod config;
 pub mod renderer;
+mod vertex;
 
 pub use config::RenderWindowConfig;
 pub use renderer::Renderer;
+pub(crate) use vertex::Vertex;
diff --git a/src/renderer.rs b/src/renderer.rs
index 2264ab5..dc8ecb2 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -1,7 +1,9 @@
-use crate::config::RenderWindowConfig;
+use std::convert::TryInto;
+
+use crate::{vertex::SQUARE, RenderWindowConfig, Vertex};
 use pollster::FutureExt;
 use thiserror::Error;
-use wgpu::include_wgsl;
+use wgpu::{include_wgsl, util::DeviceExt};
 use winit::{
 	dpi::PhysicalSize,
 	error::OsError,
@@ -40,6 +42,8 @@ pub struct Renderer {
 	queue: wgpu::Queue,
 	surface_config: wgpu::SurfaceConfiguration,
 	render_pipeline: wgpu::RenderPipeline,
+	square_vertex_buffer: wgpu::Buffer,
+	square_vertices: u32,
 	window: Window,
 }
 
@@ -100,7 +104,7 @@ impl Renderer {
 				None,
 			)
 			.block_on()
-			.unwrap();
+			.expect("there was no device with the selected features");
 
 		// configuration for the surface
 		let surface_config = config.to_surface_configuration(
@@ -124,7 +128,7 @@ impl Renderer {
 			vertex: wgpu::VertexState {
 				module: &shader,
 				entry_point: "vs_main",
-				buffers: &[],
+				buffers: &[Vertex::desc()],
 			},
 			// information about the fragment shader
 			fragment: Some(wgpu::FragmentState {
@@ -156,12 +160,25 @@ impl Renderer {
 			multiview: None,
 		});
 
+		// the vertex buffer used for rendering squares
+		let square_vertices = SQUARE
+			.len()
+			.try_into()
+			.expect("expected fewer than 3 billion vertices in a square");
+		let square_vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+			label: Some("Square Vertex Buffer"),
+			contents: bytemuck::cast_slice(&SQUARE),
+			usage: wgpu::BufferUsages::VERTEX,
+		});
+
 		Ok(Self {
 			surface,
 			device,
 			queue,
 			surface_config,
 			render_pipeline,
+			square_vertex_buffer,
+			square_vertices,
 			window,
 		})
 	}
@@ -214,7 +231,8 @@ impl Renderer {
 			});
 
 			render_pass.set_pipeline(&self.render_pipeline);
-			render_pass.draw(0..4, 0..1);
+			render_pass.set_vertex_buffer(0, self.square_vertex_buffer.slice(..));
+			render_pass.draw(0..self.square_vertices, 0..1);
 		}
 		// the encoder can't finish building the command buffer until the
 		// render pass is dropped
diff --git a/src/vertex.rs b/src/vertex.rs
new file mode 100644
index 0000000..7735801
--- /dev/null
+++ b/src/vertex.rs
@@ -0,0 +1,34 @@
+use std::mem::size_of;
+
+use bytemuck::{Pod, Zeroable};
+
+pub const SQUARE: [Vertex; 4] = [
+	Vertex::new(-0.5, -0.5),
+	Vertex::new(0.5, -0.5),
+	Vertex::new(-0.5, 0.5),
+	Vertex::new(0.5, 0.5),
+];
+
+#[repr(C)]
+#[derive(Copy, Clone, Debug, PartialEq, Pod, Zeroable)]
+pub struct Vertex {
+	position: [f32; 2],
+}
+
+impl Vertex {
+	const fn new(x: f32, y: f32) -> Self {
+		Self { position: [x, y] }
+	}
+}
+
+impl Vertex {
+	const ATTRIBUTES: [wgpu::VertexAttribute; 1] = wgpu::vertex_attr_array![0 => Float32x2];
+
+	pub(crate) const fn desc<'a>() -> wgpu::VertexBufferLayout<'a> {
+		wgpu::VertexBufferLayout {
+			array_stride: size_of::<Self>() as wgpu::BufferAddress,
+			step_mode: wgpu::VertexStepMode::Vertex,
+			attributes: &Self::ATTRIBUTES,
+		}
+	}
+}
-- 
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