docs(edu): outline shader programming chapter and create section tickets [edu-4u7w]

Add shaders.md with 18 stub sections across 6 parts (GPU model,
wgpu setup, vertex/fragment shaders, textures, compute shaders,
going further). Create beans tickets edu-5g0l through edu-7m8d
for each section. Add # Graphics section to SUMMARY.md.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

edu/.beans/edu-10m1--9-exercise-2-draw-a-coloured-triangle.md

@@ -0,0 +1,11 @@
+---
+# edu-10m1
+title: '§9 Exercise 2: draw a coloured triangle'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:52Z
+updated_at: 2026-03-13T19:54:52Z
+parent: edu-4u7w
+---
+
+Write the exercise to draw a hard-coded coloured triangle: define three vertices in a vertex buffer, write a vertex shader that passes colour through, write a fragment shader that outputs the interpolated colour. First rendered geometry. Part 3 of the Shader Programming chapter.

edu/.beans/edu-1nox--17-signed-distance-fields-for-font-rendering.md

@@ -0,0 +1,11 @@
+---
+# edu-1nox
+title: §17 Signed Distance Fields for font rendering
+status: todo
+type: task
+created_at: 2026-03-13T19:55:11Z
+updated_at: 2026-03-13T19:55:11Z
+parent: edu-4u7w
+---
+
+Write the conceptual section on SDFs for font rendering: what an SDF encodes, why it scales better than bitmaps, how to threshold and anti-alias in the fragment shader. Brief — reading and intuition only. Part 6 of the Shader Programming chapter.

edu/.beans/edu-2ak3--3-what-is-wgsl-syntax-overview.md

@@ -0,0 +1,11 @@
+---
+# edu-2ak3
+title: §3 What is WGSL? Syntax overview
+status: todo
+type: task
+created_at: 2026-03-13T19:54:41Z
+updated_at: 2026-03-13T19:54:41Z
+parent: edu-4u7w
+---
+
+Write the WGSL syntax overview: types (scalars, vectors, matrices), functions, entry points, built-in variables (@vertex, @fragment, @builtin), uniforms and bindings. Show annotated snippets of a minimal vertex+fragment shader pair. Part 1 of the Shader Programming chapter.

edu/.beans/edu-2sqo--13-compute-pipelines-dispatching-work-groups.md

@@ -0,0 +1,11 @@
+---
+# edu-2sqo
+title: '§13 Compute pipelines: dispatching work groups'
+status: todo
+type: task
+created_at: 2026-03-13T19:55:02Z
+updated_at: 2026-03-13T19:55:02Z
+parent: edu-4u7w
+---
+
+Write the lesson on compute shaders: ComputePipeline vs RenderPipeline, dispatch_workgroups, workgroup size declarations in WGSL, global_invocation_id and how threads are indexed. Part 5 of the Shader Programming chapter.

edu/.beans/edu-3l9h--7-vertices-buffers-and-the-vertex-shader.md

@@ -0,0 +1,11 @@
+---
+# edu-3l9h
+title: §7 Vertices, buffers, and the vertex shader
+status: todo
+type: task
+created_at: 2026-03-13T19:54:49Z
+updated_at: 2026-03-13T19:54:49Z
+parent: edu-4u7w
+---
+
+Write the lesson on vertex data: vertex structs in Rust, VertexBufferLayout, uploading a buffer to the GPU with wgpu::util::DeviceExt, and what the vertex shader receives (position, colour, normals). Part 3 of the Shader Programming chapter.

edu/.beans/edu-4u7w--edu-write-chapter-on-shader-programming.md

@@ -1,11 +1,11 @@
 ---
 # edu-4u7w
 title: 'edu: write chapter on shader programming'
-status: todo
+status: in-progress
-type: task
+type: feature
 priority: low
 created_at: 2026-03-10T23:30:00Z
-updated_at: 2026-03-10T23:30:00Z
+updated_at: 2026-03-13T19:54:32Z
 ---
 
 ## Background

edu/.beans/edu-5g0l--1-cpu-vs-gpu-parallel-execution-model.md

@@ -0,0 +1,11 @@
+---
+# edu-5g0l
+title: '§1 CPU vs GPU: parallel execution model'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:37Z
+updated_at: 2026-03-13T19:54:37Z
+parent: edu-4u7w
+---
+
+Write the lesson on the CPU vs GPU execution model: SIMD vs SIMT, thread hierarchies (threads, warps/waves, workgroups), why GPUs excel at data-parallel work and struggle with branching. Part 1 of the Shader Programming chapter.

edu/.beans/edu-6jjp--5-exercise-1-create-a-window-and-clear-it-to-a-col.md

@@ -0,0 +1,11 @@
+---
+# edu-6jjp
+title: '§5 Exercise 1: create a window and clear it to a colour'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:44Z
+updated_at: 2026-03-13T19:54:44Z
+parent: edu-4u7w
+---
+
+Write the first hands-on exercise: create a winit window, initialise a wgpu surface, and clear it to a solid colour each frame. Walk through Instance → Adapter → Device → Surface → RenderPass with annotated Rust code. The GPU hello world. Part 2 of the Shader Programming chapter.

edu/.beans/edu-7m8d--18-resources-learn-wgpu-shadertoy-the-book-of-shad.md

@@ -0,0 +1,11 @@
+---
+# edu-7m8d
+title: '§18 Resources: Learn WGPU, Shadertoy, The Book of Shaders'
+status: todo
+type: task
+created_at: 2026-03-13T19:55:12Z
+updated_at: 2026-03-13T19:55:12Z
+parent: edu-4u7w
+---
+
+Write the resources and next-steps section: links and descriptions for the Learn WGPU tutorial, Shadertoy for experimentation, The Book of Shaders for mathematical foundations, and any other curated pointers. Part 6 of the Shader Programming chapter.

edu/.beans/edu-9lda--16-post-processing-effects-bloom-blur-conceptual-o.md

@@ -0,0 +1,11 @@
+---
+# edu-9lda
+title: '§16 Post-processing effects (bloom, blur): conceptual overview'
+status: todo
+type: task
+created_at: 2026-03-13T19:55:11Z
+updated_at: 2026-03-13T19:55:11Z
+parent: edu-4u7w
+---
+
+Write the conceptual overview of post-processing: render to texture (off-screen framebuffer), Gaussian blur as a separable two-pass compute shader, bloom as blur applied to bright regions. No full exercise — reading only. Part 6 of the Shader Programming chapter.

edu/.beans/edu-bycd--11-texture-coordinates-uvs-texture-creation-sample.md

@@ -0,0 +1,11 @@
+---
+# edu-bycd
+title: §11 Texture coordinates (UVs), texture creation, sampler config
+status: todo
+type: task
+created_at: 2026-03-13T19:54:56Z
+updated_at: 2026-03-13T19:54:56Z
+parent: edu-4u7w
+---
+
+Write the lesson on textures: UV coordinates, wgpu texture creation from image data, TextureView, Sampler configuration (filter modes, address modes), and bind group layout for textures. Part 4 of the Shader Programming chapter.

edu/.beans/edu-cr0w--10-exercise-3-animate-the-triangle-using-a-time-un.md

@@ -0,0 +1,11 @@
+---
+# edu-cr0w
+title: '§10 Exercise 3: animate the triangle using a time uniform'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:54Z
+updated_at: 2026-03-13T19:54:54Z
+parent: edu-4u7w
+---
+
+Write the exercise to animate the coloured triangle: introduce uniform buffers, upload a time value each frame, rotate or pulse the triangle in the vertex shader using the time uniform. Introduces the uniform/bind-group pattern. Part 3 of the Shader Programming chapter.

edu/.beans/edu-exby--15-exercise-5-gpu-accelerate-a-particle-simulation.md

@@ -0,0 +1,11 @@
+---
+# edu-exby
+title: '§15 Exercise 5: GPU-accelerate a particle simulation'
+status: todo
+type: task
+created_at: 2026-03-13T19:55:05Z
+updated_at: 2026-03-13T19:55:05Z
+parent: edu-4u7w
+---
+
+Write the compute shader exercise: implement an N-body or simple gravity particle simulation. Store particle positions and velocities in storage buffers, update them in a compute shader each frame, render the result as points. Part 5 of the Shader Programming chapter.

edu/.beans/edu-ga8p--8-interpolation-and-the-fragment-shader.md

@@ -0,0 +1,11 @@
+---
+# edu-ga8p
+title: §8 Interpolation and the fragment shader
+status: todo
+type: task
+created_at: 2026-03-13T19:54:50Z
+updated_at: 2026-03-13T19:54:50Z
+parent: edu-4u7w
+---
+
+Write the lesson on rasterisation and interpolation: how values output from the vertex shader are interpolated across fragments, what the fragment shader receives and outputs (colour), and how the pipeline assembles a final image. Part 3 of the Shader Programming chapter.

edu/.beans/edu-hrfy--6-the-render-loop-swap-chains-frames-command-encod.md

@@ -0,0 +1,11 @@
+---
+# edu-hrfy
+title: '§6 The render loop: swap chains, frames, command encoders'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:44Z
+updated_at: 2026-03-13T19:54:44Z
+parent: edu-4u7w
+---
+
+Write the lesson on the wgpu render loop: SurfaceTexture acquisition, CommandEncoder, RenderPass, queue submission, present. Explain double/triple buffering conceptually. Part 2 of the Shader Programming chapter.

edu/.beans/edu-j35d--4-what-is-wgpu-cross-platform-graphics-api-in-rust.md

@@ -0,0 +1,11 @@
+---
+# edu-j35d
+title: §4 What is wgpu? Cross-platform graphics API in Rust
+status: todo
+type: task
+created_at: 2026-03-13T19:54:43Z
+updated_at: 2026-03-13T19:54:43Z
+parent: edu-4u7w
+---
+
+Write the wgpu introduction: what it is, how it maps to WebGPU/Vulkan/Metal/D3D12, the key types (Instance, Adapter, Device, Queue, Surface), and how it differs from OpenGL. Part 2 of the Shader Programming chapter.

edu/.beans/edu-r52d--2-the-programmable-pipeline-vertex-fragment-comput.md

@@ -0,0 +1,11 @@
+---
+# edu-r52d
+title: '§2 The programmable pipeline: vertex, fragment, compute shaders'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:39Z
+updated_at: 2026-03-13T19:54:39Z
+parent: edu-4u7w
+---
+
+Write the lesson on the programmable graphics pipeline: what happens at each stage, which stages are programmable, what vertex and fragment shaders each receive and output, and where compute shaders fit. Part 1 of the Shader Programming chapter.

edu/.beans/edu-uxa1--14-storage-buffers-and-readwrite-access-from-wgsl.md

@@ -0,0 +1,11 @@
+---
+# edu-uxa1
+title: §14 Storage buffers and read/write access from WGSL
+status: todo
+type: task
+created_at: 2026-03-13T19:55:04Z
+updated_at: 2026-03-13T19:55:04Z
+parent: edu-4u7w
+---
+
+Write the lesson on storage buffers: var<storage, read_write> in WGSL, creating STORAGE | COPY_SRC buffers in Rust, reading results back to CPU, and the difference between uniform and storage buffers. Part 5 of the Shader Programming chapter.

edu/.beans/edu-xv9j--12-exercise-4-render-a-textured-quad.md

@@ -0,0 +1,11 @@
+---
+# edu-xv9j
+title: '§12 Exercise 4: render a textured quad'
+status: todo
+type: task
+created_at: 2026-03-13T19:54:58Z
+updated_at: 2026-03-13T19:54:58Z
+parent: edu-4u7w
+---
+
+Write the exercise to render a textured quad: two triangles forming a rectangle, UV coordinates per vertex, load an image with the image crate, upload to a wgpu texture, sample it in the fragment shader. Part 4 of the Shader Programming chapter.

edu/src/SUMMARY.md

@@ -17,3 +17,7 @@
 # Compilers
 
 - [Writing a Lisp-to-C Compiler in Rust](lisp-compiler.md)
+
+# Graphics
+
+- [Shader Programming with wgpu and WGSL](shaders.md)

edu/src/shaders.md

@@ -0,0 +1,163 @@
+# Shader Programming with wgpu and WGSL
+
+This document is a self-guided course on GPU shader programming. It is organised into six parts: the GPU execution model, setting up with `wgpu`, vertex and fragment shaders, textures and samplers, compute shaders, and a look at where to go next. Each section is either a reading lesson or a hands-on Rust programming exercise. Sections marked 🚧 are stubs whose full content is tracked in a beans ticket — follow the ticket ID to find the detailed learning objectives and instructions.
+
+---
+
+## Table of Contents
+
+**Part 1 — The GPU and the Graphics Pipeline**
+
+1. [CPU vs GPU: parallel execution model](#1-cpu-vs-gpu-parallel-execution-model)
+2. [The programmable pipeline: vertex, fragment, compute shaders](#2-the-programmable-pipeline-vertex-fragment-compute-shaders)
+3. [What is WGSL? Syntax overview](#3-what-is-wgsl-syntax-overview)
+
+**Part 2 — Setting Up with wgpu**
+
+4. [What is wgpu? Cross-platform graphics API in Rust](#4-what-is-wgpu-cross-platform-graphics-api-in-rust)
+5. [Exercise 1: create a window and clear it to a colour](#5-exercise-1-create-a-window-and-clear-it-to-a-colour)
+6. [The render loop: swap chains, frames, command encoders](#6-the-render-loop-swap-chains-frames-command-encoders)
+
+**Part 3 — Vertex and Fragment Shaders**
+
+7. [Vertices, buffers, and the vertex shader](#7-vertices-buffers-and-the-vertex-shader)
+8. [Interpolation and the fragment shader](#8-interpolation-and-the-fragment-shader)
+9. [Exercise 2: draw a coloured triangle](#9-exercise-2-draw-a-coloured-triangle)
+10. [Exercise 3: animate the triangle using a time uniform](#10-exercise-3-animate-the-triangle-using-a-time-uniform)
+
+**Part 4 — Textures and Samplers**
+
+11. [Texture coordinates (UVs), texture creation, sampler config](#11-texture-coordinates-uvs-texture-creation-sampler-config)
+12. [Exercise 4: render a textured quad](#12-exercise-4-render-a-textured-quad)
+
+**Part 5 — Compute Shaders**
+
+13. [Compute pipelines: dispatching work groups](#13-compute-pipelines-dispatching-work-groups)
+14. [Storage buffers and read/write access from WGSL](#14-storage-buffers-and-readwrite-access-from-wgsl)
+15. [Exercise 5: GPU-accelerate a particle simulation](#15-exercise-5-gpu-accelerate-a-particle-simulation)
+
+**Part 6 — Going Further**
+
+16. [Post-processing effects (bloom, blur): conceptual overview](#16-post-processing-effects-bloom-blur-conceptual-overview)
+17. [Signed Distance Fields for font rendering](#17-signed-distance-fields-for-font-rendering)
+18. [Resources: Learn WGPU, Shadertoy, The Book of Shaders](#18-resources-learn-wgpu-shadertoy-the-book-of-shaders)
+
+---
+
+## Part 1 — The GPU and the Graphics Pipeline
+
+### 1. CPU vs GPU: parallel execution model
+
+🚧 This section is a stub. Full content tracked in [edu-5g0l].
+
+---
+
+### 2. The programmable pipeline: vertex, fragment, compute shaders
+
+🚧 This section is a stub. Full content tracked in [edu-r52d].
+
+---
+
+### 3. What is WGSL? Syntax overview
+
+🚧 This section is a stub. Full content tracked in [edu-2ak3].
+
+---
+
+## Part 2 — Setting Up with wgpu
+
+### 4. What is wgpu? Cross-platform graphics API in Rust
+
+🚧 This section is a stub. Full content tracked in [edu-j35d].
+
+---
+
+### 5. Exercise 1: create a window and clear it to a colour
+
+🚧 This section is a stub. Full content tracked in [edu-6jjp].
+
+---
+
+### 6. The render loop: swap chains, frames, command encoders
+
+🚧 This section is a stub. Full content tracked in [edu-hrfy].
+
+---
+
+## Part 3 — Vertex and Fragment Shaders
+
+### 7. Vertices, buffers, and the vertex shader
+
+🚧 This section is a stub. Full content tracked in [edu-3l9h].
+
+---
+
+### 8. Interpolation and the fragment shader
+
+🚧 This section is a stub. Full content tracked in [edu-ga8p].
+
+---
+
+### 9. Exercise 2: draw a coloured triangle
+
+🚧 This section is a stub. Full content tracked in [edu-10m1].
+
+---
+
+### 10. Exercise 3: animate the triangle using a time uniform
+
+🚧 This section is a stub. Full content tracked in [edu-cr0w].
+
+---
+
+## Part 4 — Textures and Samplers
+
+### 11. Texture coordinates (UVs), texture creation, sampler config
+
+🚧 This section is a stub. Full content tracked in [edu-bycd].
+
+---
+
+### 12. Exercise 4: render a textured quad
+
+🚧 This section is a stub. Full content tracked in [edu-xv9j].
+
+---
+
+## Part 5 — Compute Shaders
+
+### 13. Compute pipelines: dispatching work groups
+
+🚧 This section is a stub. Full content tracked in [edu-2sqo].
+
+---
+
+### 14. Storage buffers and read/write access from WGSL
+
+🚧 This section is a stub. Full content tracked in [edu-uxa1].
+
+---
+
+### 15. Exercise 5: GPU-accelerate a particle simulation
+
+🚧 This section is a stub. Full content tracked in [edu-exby].
+
+---
+
+## Part 6 — Going Further
+
+### 16. Post-processing effects (bloom, blur): conceptual overview
+
+🚧 This section is a stub. Full content tracked in [edu-9lda].
+
+---
+
+### 17. Signed Distance Fields for font rendering
+
+🚧 This section is a stub. Full content tracked in [edu-1nox].
+
+---
+
+### 18. Resources: Learn WGPU, Shadertoy, The Book of Shaders
+
+🚧 This section is a stub. Full content tracked in [edu-7m8d].