From 0bd709fc8bbaed104ab13eed6910ca9a15a6b2b6 Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Sat, 11 Jan 2025 01:18:20 +0300
Subject: [PATCH] Basic shader test

---
 src/main.rs      | 45 +++++++++++++++++++++++++++++++++++++++++----
 src/present.wgsl | 28 ++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 4 deletions(-)
 create mode 100644 src/present.wgsl

diff --git a/src/main.rs b/src/main.rs
index 699205b..64f15dc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 use std::error::Error;
 
+use glam::uvec2;
 use winit::{
 	event::{Event, WindowEvent},
 	event_loop::EventLoop,
@@ -15,22 +16,56 @@ fn main() {
 		.unwrap();
 
 	let (device, queue, surface) = pollster::block_on(init_gpu(window)).unwrap();
-
 	let format = wgpu::TextureFormat::Bgra8UnormSrgb;
 	let mut surface_configured = false;
+
+	let present_shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+		label: Some("present"),
+		source: wgpu::ShaderSource::Wgsl(include_str!("present.wgsl").into()),
+	});
+	let present_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+		label: None,
+		layout: None,
+		vertex: wgpu::VertexState {
+			module: &present_shader,
+			entry_point: None,
+			compilation_options: wgpu::PipelineCompilationOptions::default(),
+			buffers: &[],
+		},
+		primitive: wgpu::PrimitiveState {
+			topology: wgpu::PrimitiveTopology::TriangleStrip,
+			..Default::default()
+		},
+		depth_stencil: None,
+		multisample: wgpu::MultisampleState::default(),
+		fragment: Some(wgpu::FragmentState {
+			module: &present_shader,
+			entry_point: None,
+			compilation_options: wgpu::PipelineCompilationOptions::default(),
+			targets: &[Some(wgpu::ColorTargetState {
+				format,
+				blend: None,
+				write_mask: wgpu::ColorWrites::ALL,
+			})],
+		}),
+		multiview: None,
+		cache: None,
+	});
+
 	#[allow(deprecated)]
 	event_loop
 		.run(move |event, control_flow| match event {
 			Event::WindowEvent { ref event, window_id } if window_id == window.id() => match event {
 				WindowEvent::CloseRequested => control_flow.exit(),
 				WindowEvent::Resized(physical_size) => {
+					let size = uvec2(physical_size.width, physical_size.height);
 					surface.configure(
 						&device,
 						&wgpu::SurfaceConfiguration {
 							usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_DST,
 							format,
-							width: physical_size.width,
-							height: physical_size.height,
+							width: size.x,
+							height: size.y,
 							present_mode: wgpu::PresentMode::Fifo,
 							alpha_mode: wgpu::CompositeAlphaMode::Auto,
 							view_formats: vec![],
@@ -46,7 +81,7 @@ fn main() {
 					let output = surface.get_current_texture().unwrap();
 					let view = output.texture.create_view(&wgpu::TextureViewDescriptor::default());
 					let mut encoder = device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
-					let render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+					let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
 						label: None,
 						color_attachments: &[Some(wgpu::RenderPassColorAttachment {
 							view: &view,
@@ -60,6 +95,8 @@ fn main() {
 						occlusion_query_set: None,
 						timestamp_writes: None,
 					});
+					render_pass.set_pipeline(&present_pipeline);
+					render_pass.draw(0..4, 0..1);
 					drop(render_pass);
 					queue.submit(std::iter::once(encoder.finish()));
 					output.present();
diff --git a/src/present.wgsl b/src/present.wgsl
new file mode 100644
index 0000000..0663c5c
--- /dev/null
+++ b/src/present.wgsl
@@ -0,0 +1,28 @@
+const SEED = 0x4ae95672u;
+
+struct Varying {
+	@location(0) uv: vec2f,
+	@builtin(position) screen: vec4f,
+}
+
+@vertex
+fn on_vertex(@builtin(vertex_index) vi: u32) -> Varying {
+	let uv = vec2f(vec2(vi, vi >> 1u) & vec2(1u));
+	let screen = vec4(uv * 2. - 1., 0., 1.);
+	return Varying(vec2(uv.x, 1. - uv.y), screen);
+}
+
+@fragment
+fn on_fragment(in: Varying) -> @location(0) vec4f {
+	let x = bitcast<u32>(in.uv.x);
+	let y = bitcast<u32>(in.uv.y);
+	let rand = hash(hash(hash(SEED) ^ hash(x)) ^ hash(y));
+	return vec4f(f32(rand) / 0x1p32);
+}
+
+fn hash(key : u32) -> u32 {
+        var v = key;
+        v *= 0xb384af1bu;
+        v ^= v >> 15u;
+        return v;
+}