316 lines
11 KiB
Rust
316 lines
11 KiB
Rust
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use std::borrow::Cow;
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use std::sync::Arc;
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use std::time::Instant;
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use thiserror::Error;
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use winit::window::Window;
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use futures::executor::block_on;
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#[derive(Debug, Error)]
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pub enum ContextError {
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#[error("Failed to create WGPU surface: {0}")]
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SurfaceCreationFailure(#[from] wgpu::CreateSurfaceError),
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}
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/// This WGSL shader generates a cube procedurally and rotates it around the Y axis.
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/// A uniform (u.time) is used as the rotation angle. After rotation, a simple
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/// perspective projection is applied (dividing x,y by z) to produce clip-space coordinates.
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const CUBE_SHADER: &str = r#"
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struct Uniforms {
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time: f32,
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// pad to 16 bytes (uniforms require 16-byte alignment)
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padding0: f32,
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padding1: f32,
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padding2: f32,
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};
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@group(0) @binding(0)
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var<uniform> u: Uniforms;
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// Returns a rotation matrix about the Y axis.
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fn rotationY(angle: f32) -> mat3x3<f32> {
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let c = cos(angle);
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let s = sin(angle);
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return mat3x3<f32>(
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vec3<f32>( c, 0.0, s),
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vec3<f32>(0.0, 1.0, 0.0),
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vec3<f32>(-s, 0.0, c)
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);
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}
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@vertex
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fn vs_main(@builtin(vertex_index) vid: u32) -> @builtin(position) vec4<f32> {
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// We generate 36 vertices (6 faces * 6 vertices per face)
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let face: u32 = vid / 6u; // which face (0..5)
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let corner: u32 = vid % 6u; // which corner within that face
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// Offsets for the two triangles that make up a face:
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// (these are in a 2D space, later used to compute positions on the face)
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var offsets = array<vec2<f32>, 6>(
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vec2<f32>(-1.0, -1.0),
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vec2<f32>( 1.0, -1.0),
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vec2<f32>( 1.0, 1.0),
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vec2<f32>( 1.0, 1.0),
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vec2<f32>(-1.0, 1.0),
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vec2<f32>(-1.0, -1.0)
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);
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var center: vec3<f32>;
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var uvec: vec3<f32>;
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var vvec: vec3<f32>;
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// Define each face of the cube (cube of side length 1 centered at origin)
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if (face == 0u) {
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// Front face (z = +0.5)
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center = vec3<f32>(0.0, 0.0, 0.5);
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uvec = vec3<f32>(0.5, 0.0, 0.0);
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vvec = vec3<f32>(0.0, 0.5, 0.0);
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} else if (face == 1u) {
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// Back face (z = -0.5)
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center = vec3<f32>(0.0, 0.0, -0.5);
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uvec = vec3<f32>(-0.5, 0.0, 0.0);
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vvec = vec3<f32>(0.0, 0.5, 0.0);
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} else if (face == 2u) {
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// Right face (x = +0.5)
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center = vec3<f32>(0.5, 0.0, 0.0);
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uvec = vec3<f32>(0.0, 0.0, -0.5);
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vvec = vec3<f32>(0.0, 0.5, 0.0);
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} else if (face == 3u) {
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// Left face (x = -0.5)
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center = vec3<f32>(-0.5, 0.0, 0.0);
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uvec = vec3<f32>(0.0, 0.0, 0.5);
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vvec = vec3<f32>(0.0, 0.5, 0.0);
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} else if (face == 4u) {
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// Top face (y = +0.5)
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center = vec3<f32>(0.0, 0.5, 0.0);
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uvec = vec3<f32>(0.5, 0.0, 0.0);
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vvec = vec3<f32>(0.0, 0.0, -0.5);
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} else {
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// Bottom face (y = -0.5)
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center = vec3<f32>(0.0, -0.5, 0.0);
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uvec = vec3<f32>(0.5, 0.0, 0.0);
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vvec = vec3<f32>(0.0, 0.0, 0.5);
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}
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let off = offsets[corner];
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var pos = center + off.x * uvec + off.y * vvec;
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// Apply a rotation about the Y axis using the uniform time.
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let rot = rotationY(u.time);
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pos = rot * pos;
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// Translate the cube so it is in front of the camera.
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pos = pos + vec3<f32>(0.0, 0.0, 2.0);
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// Simple perspective projection: divide x and y by z.
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let projected = vec2<f32>(pos.x / pos.z, pos.y / pos.z);
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return vec4<f32>(projected, 0.0, 1.0);
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}
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@fragment
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fn fs_main() -> @location(0) vec4<f32> {
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// Output a fixed color.
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return vec4<f32>(0.7, 0.7, 0.9, 1.0);
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}
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"#;
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pub struct WgpuCtx<'window> {
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device: wgpu::Device,
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queue: wgpu::Queue,
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surface: wgpu::Surface<'window>,
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surface_config: wgpu::SurfaceConfiguration,
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adapter: wgpu::Adapter,
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render_pipeline: wgpu::RenderPipeline,
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uniform_buffer: wgpu::Buffer,
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start_time: Instant,
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}
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impl<'window> WgpuCtx<'window> {
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pub async fn new(window: Arc<Window>) -> Result<WgpuCtx<'window>, ContextError> {
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let instance = wgpu::Instance::default();
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let surface = instance.create_surface(Arc::clone(&window))?;
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let adapter = instance
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.request_adapter(&wgpu::RequestAdapterOptions {
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power_preference: wgpu::PowerPreference::default(),
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force_fallback_adapter: false,
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compatible_surface: Some(&surface),
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})
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.await
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.expect("Failed to obtain render adapter");
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let (device, queue) = adapter
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.request_device(
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&wgpu::DeviceDescriptor {
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label: None,
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required_features: wgpu::Features::empty(),
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required_limits: wgpu::Limits::downlevel_webgl2_defaults()
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.using_resolution(adapter.limits()),
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memory_hints: wgpu::MemoryHints::Performance,
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},
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None,
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)
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.await
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.expect("Failed to create rendering device");
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let size = window.inner_size();
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let width = size.width.max(1);
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let height = size.height.max(1);
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let surface_config = surface.get_default_config(&adapter, width, height).unwrap();
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surface.configure(&device, &surface_config);
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// Create a uniform buffer (16 bytes to satisfy alignment requirements)
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let uniform_buffer = device.create_buffer(&wgpu::BufferDescriptor {
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label: Some("Uniform Buffer"),
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size: 16,
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usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
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mapped_at_creation: false,
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});
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// Create the shader module from the inline WGSL shader.
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let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
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label: Some("Cube Shader"),
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source: wgpu::ShaderSource::Wgsl(Cow::Borrowed(CUBE_SHADER)),
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});
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// Create a bind group layout for the uniform.
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let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
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label: Some("Uniform Bind Group Layout"),
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entries: &[wgpu::BindGroupLayoutEntry {
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binding: 0,
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visibility: wgpu::ShaderStages::VERTEX,
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ty: wgpu::BindingType::Buffer {
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ty: wgpu::BufferBindingType::Uniform,
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has_dynamic_offset: false,
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min_binding_size: wgpu::BufferSize::new(16),
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},
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count: None,
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}],
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});
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// Create the pipeline layout.
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let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
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label: Some("Cube Pipeline Layout"),
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bind_group_layouts: &[&bind_group_layout],
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push_constant_ranges: &[],
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});
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// TODO: add proper vertex buffer
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let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
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label: Some("Cube Render Pipeline"),
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layout: Some(&pipeline_layout),
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vertex: wgpu::VertexState {
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module: &shader,
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entry_point: Some("vs_main"),
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buffers: &[],
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compilation_options: wgpu::PipelineCompilationOptions::default(),
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},
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fragment: Some(wgpu::FragmentState {
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module: &shader,
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entry_point: Some("fs_main"),
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targets: &[Some(wgpu::ColorTargetState {
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format: surface_config.format,
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blend: Some(wgpu::BlendState::REPLACE),
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write_mask: wgpu::ColorWrites::ALL,
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})],
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compilation_options: wgpu::PipelineCompilationOptions::default(),
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}),
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primitive: wgpu::PrimitiveState {
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topology: wgpu::PrimitiveTopology::TriangleList,
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strip_index_format: None,
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front_face: wgpu::FrontFace::Ccw,
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cull_mode: None,
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polygon_mode: wgpu::PolygonMode::Fill,
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unclipped_depth: false,
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conservative: false,
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},
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depth_stencil: None,
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multisample: wgpu::MultisampleState {
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count: 1,
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mask: !0,
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alpha_to_coverage_enabled: false,
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},
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multiview: None,
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cache: None,
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});
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Ok(WgpuCtx {
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device,
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queue,
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surface,
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surface_config,
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adapter,
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render_pipeline,
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uniform_buffer,
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start_time: Instant::now(),
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})
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}
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pub fn new_blocking(window: Arc<Window>) -> Result<WgpuCtx<'window>, ContextError> {
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block_on(Self::new(window))
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}
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pub fn resize(&mut self, new_size: (u32, u32)) {
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let (width, height) = new_size;
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self.surface_config.width = width.max(1);
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self.surface_config.height = height.max(1);
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self.surface.configure(&self.device, &self.surface_config);
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}
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pub fn draw(&mut self) {
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// Update the uniform buffer with the elapsed time.
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let elapsed = self.start_time.elapsed().as_secs_f32();
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// Pack into 4 floats (pad to 16 bytes)
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let time_data = [elapsed, 0.0, 0.0, 0.0];
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self.queue.write_buffer(&self.uniform_buffer, 0, bytemuck::cast_slice(&time_data));
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let surface_texture = self
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.surface
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.get_current_texture()
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.expect("Failed to get surface texture");
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let view = surface_texture
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.texture
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.create_view(&wgpu::TextureViewDescriptor::default());
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let mut encoder =
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self.device
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.create_command_encoder(&wgpu::CommandEncoderDescriptor {
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label: Some("Cube Command Encoder"),
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});
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{
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let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
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label: Some("Cube Render Pass"),
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color_attachments: &[Some(wgpu::RenderPassColorAttachment {
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view: &view,
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resolve_target: None,
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ops: wgpu::Operations {
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load: wgpu::LoadOp::Clear(wgpu::Color {
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r: 0.1,
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g: 0.2,
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b: 0.3,
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a: 1.0,
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}),
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store: wgpu::StoreOp::Store,
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},
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})],
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depth_stencil_attachment: None,
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timestamp_writes: None,
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occlusion_query_set: None,
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});
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render_pass.set_pipeline(&self.render_pipeline);
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// Create a bind group on the fly for the uniform.
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let bind_group = self.device.create_bind_group(&wgpu::BindGroupDescriptor {
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label: Some("Uniform Bind Group (per draw)"),
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layout: &self.render_pipeline.get_bind_group_layout(0),
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entries: &[wgpu::BindGroupEntry {
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binding: 0,
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resource: self.uniform_buffer.as_entire_binding(),
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}],
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});
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render_pass.set_bind_group(0, &bind_group, &[]);
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// Draw 36 vertices (6 faces × 6 vertices)
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render_pass.draw(0..36, 0..1);
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}
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self.queue.submit(Some(encoder.finish()));
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surface_texture.present();
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}
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}
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