Shader Craft

A unified skill covering 36 GLSL shader techniques (ShaderToy-compatible) for real-time visual effects.

Invocation

CODEBLOCK0

INLINECODE0 contains the user's request (e.g. "create a raymarched SDF scene with soft shadows").

Skill Structure

CODEBLOCK1

How to Use

1. 1. Read the Technique Routing Table below to identify which technique(s) match the user's request
2. Read the relevant file(s) from techniques/ — each file contains core principles, implementation steps, and complete code templates
3. If you need deeper understanding (math derivations, advanced patterns), follow the reference link at the bottom of each technique file to INLINECODE2
4. Apply the WebGL2 Adaptation Rules below when generating standalone HTML pages

Technique Routing Table

User wants to create...	Primary technique	Combine with
3D objects / scenes from math	ray-marching + sdf-3d	lighting-model, shadow-techniques
Complex 3D shapes (booleans, blends)

csg-boolean-operations | sdf-3d, ray-marching | | Infinite repeating patterns in 3D | domain-repetition | sdf-3d, ray-marching | | Organic / warped shapes | domain-warping | procedural-noise | | Fluid / smoke / ink effects | fluid-simulation | multipass-buffer | | Particle effects (fire, sparks, snow) | particle-system | procedural-noise, color-palette | | Physically-based simulations | simulation-physics | multipass-buffer | | Game of Life / reaction-diffusion | cellular-automata | multipass-buffer, color-palette | | Ocean / water surface | water-ocean | atmospheric-scattering, lighting-model | | Terrain / landscape | terrain-rendering | atmospheric-scattering, procedural-noise | | Clouds / fog / volumetric fire | volumetric-rendering | procedural-noise, atmospheric-scattering | | Sky / sunset / atmosphere | atmospheric-scattering | volumetric-rendering | | Realistic lighting (PBR, Phong) | lighting-model | shadow-techniques, ambient-occlusion | | Shadows (soft / hard) | shadow-techniques | lighting-model | | Ambient occlusion | ambient-occlusion | lighting-model, normal-estimation | | Path tracing / global illumination | path-tracing-gi | analytic-ray-tracing, multipass-buffer | | Precise ray-geometry intersections | analytic-ray-tracing | lighting-model | | Voxel worlds (Minecraft-style) | voxel-rendering | lighting-model, shadow-techniques | | Noise / FBM textures | procedural-noise | domain-warping | | Tiled 2D patterns | procedural-2d-pattern | polar-uv-manipulation | | Voronoi / cell patterns | voronoi-cellular-noise | color-palette | | Fractals (Mandelbrot, Julia, 3D) | fractal-rendering | color-palette, polar-uv-manipulation | | Color grading / palettes | color-palette | — | | Bloom / tone mapping / glitch | post-processing | multipass-buffer | | Multi-pass ping-pong buffers | multipass-buffer | — | | Texture / sampling techniques | texture-sampling | — | | Camera / matrix transforms | matrix-transform | — | | Surface normals | normal-estimation | — | | Polar coords / kaleidoscope | polar-uv-manipulation | procedural-2d-pattern | | 2D shapes / UI from SDF | sdf-2d | color-palette | | Procedural audio / music | sound-synthesis | — | | SDF tricks / optimization | sdf-tricks | sdf-3d, ray-marching | | Anti-aliased rendering | anti-aliasing | sdf-2d, post-processing | | Depth of field / motion blur / lens effects | camera-effects | post-processing, multipass-buffer | | Advanced texture mapping / no-tile textures | texture-mapping-advanced | terrain-rendering, texture-sampling | | WebGL2 shader errors / debugging | webgl-pitfalls | — |

Technique Index

Geometry & SDF

• - sdf-2d — 2D signed distance functions for shapes, UI, anti-aliased rendering
• sdf-3d — 3D signed distance functions for real-time implicit surface modeling
• csg-boolean-operations — Constructive solid geometry: union, subtraction, intersection with smooth blending
• domain-repetition — Infinite space repetition, folding, and limited tiling
• domain-warping — Distort domains with noise for organic, flowing shapes
• sdf-tricks — SDF optimization, bounding volumes, binary search refinement, hollowing, layered edges, debug visualization

Ray Casting & Lighting

• - ray-marching — Sphere tracing with SDF for 3D scene rendering
• analytic-ray-tracing — Closed-form ray-primitive intersections (sphere, plane, box, torus)
• path-tracing-gi — Monte Carlo path tracing for photorealistic global illumination
• lighting-model — Phong, Blinn-Phong, PBR (Cook-Torrance), and toon shading
• shadow-techniques — Hard shadows, soft shadows (penumbra estimation), cascade shadows
• ambient-occlusion — SDF-based AO, screen-space AO approximation
• normal-estimation — Finite-difference normals, tetrahedron technique

Simulation & Physics

• - fluid-simulation — Navier-Stokes fluid solver with advection, diffusion, pressure projection
• simulation-physics — GPU-based physics: springs, cloth, N-body gravity, collision
• particle-system — Stateless and stateful particle systems (fire, rain, sparks, galaxies)
• cellular-automata — Game of Life, reaction-diffusion (Turing patterns), sand simulation

Natural Phenomena

• - water-ocean — Gerstner waves, FFT ocean, caustics, underwater fog
• terrain-rendering — Heightfield ray marching, FBM terrain, erosion
• atmospheric-scattering — Rayleigh/Mie scattering, god rays, SSS approximation
• volumetric-rendering — Volume ray marching for clouds, fog, fire, explosions

Procedural Generation

• - procedural-noise — Value noise, Perlin, Simplex, Worley, FBM, ridged noise
• procedural-2d-pattern — Brick, hexagon, truchet, Islamic geometric patterns
• voronoi-cellular-noise — Voronoi diagrams, Worley noise, cracked earth, crystal
• fractal-rendering — Mandelbrot, Julia sets, 3D fractals (Mandelbox, Mandelbulb)
• color-palette — Cosine palettes, HSL/HSV/Oklab, dynamic color mapping

Post-Processing & Infrastructure

• - post-processing — Bloom, tone mapping (ACES, Reinhard), vignette, chromatic aberration, glitch
• multipass-buffer — Ping-pong FBO setup, state persistence across frames
• texture-sampling — Bilinear, bicubic, mipmap, procedural texture lookup
• matrix-transform — Camera look-at, projection, rotation, orbit controls
• polar-uv-manipulation — Polar/log-polar coordinates, kaleidoscope, spiral mapping
• anti-aliasing — SSAA, SDF analytical AA, temporal anti-aliasing (TAA), FXAA post-process
• camera-effects — Depth of field (thin lens), motion blur, lens distortion, film grain, vignette
• texture-mapping-advanced — Biplanar mapping, texture repetition avoidance, ray differential filtering

Audio

• - sound-synthesis — Procedural audio in GLSL: oscillators, envelopes, filters, FM synthesis

Debugging & Validation

• - webgl-pitfalls — Common WebGL2/GLSL errors: fragCoord, main() wrapper, function order, macro limitations, uniform null

WebGL2 Adaptation Rules

All technique files use ShaderToy GLSL style. When generating standalone HTML pages, apply these adaptations:

Shader Version & Output

• - Use INLINECODE5
• Shader first line: #version 300 es, fragment shader adds INLINECODE7
• Fragment shader must declare: INLINECODE8
• Vertex shader: attribute → in, varying → INLINECODE12
• Fragment shader: varying → in, gl_FragColor → fragColor, texture2D() → INLINECODE18

Fragment Coordinate

• - Use gl_FragCoord.xy instead of fragCoord (WebGL2 does not have fragCoord built-in)

CODEBLOCK2

main() Wrapper for ShaderToy Templates

• - ShaderToy uses INLINECODE22
• WebGL2 requires standard void main() entry point — always wrap mainImage:

CODEBLOCK3

Function Declaration Order

• - GLSL requires functions to be declared before use — either declare before use or reorder:

CODEBLOCK4

Macro Limitations

• - #define cannot use function calls — use const instead:

CODEBLOCK5

Script Tag Extraction

• - When extracting shader source from <script> tags, ensure #version is the first character — use .trim():

CODEBLOCK6

Common Pitfalls

• - Unused uniforms: Compiler may optimize away unused uniforms, causing gl.getUniformLocation() to return null — always use uniforms in a way the compiler cannot optimize out
• Loop indices: Use runtime constants in loops, not #define macros in some ES versions
• Terrain functions: Functions like terrainM(vec2) need XZ components — use terrainM(pos.xz + offset) not INLINECODE34

HTML Page Setup

When generating a standalone HTML page:

• - Canvas fills the entire viewport, auto-resizes on window resize
• Page background black, no scrollbars: INLINECODE35
• Implement ShaderToy-compatible uniforms: iTime, iResolution, iMouse, INLINECODE39
• For multi-pass effects (Buffer A/B), use WebGL2 framebuffer + ping-pong (see multipass-buffer technique)

Common Pitfalls

JS Variable Declaration Order (TDZ — causes white screen crash)

INLINECODE40/const variables must be declared at the top of the <script> block, before any function that references them:

CODEBLOCK7

Reason: let/const have a Temporal Dead Zone — referencing them before declaration throws ReferenceError, causing a white screen.

GLSL Compilation Errors (self-check after writing shaders)

• - Function signature mismatch: Call must exactly match definition in parameter count and types. If defined as float fbm(vec3 p), cannot call fbm(uv) with a INLINECODE48
• Reserved words as variable names: Do not use: patch, cast, sample, filter, input, output, common, partition, INLINECODE57
• Strict type matching: vec3 x = 1.0 is illegal — use vec3 x = vec3(1.0); cannot use .z to access a INLINECODE61
• No ternary on structs: ESSL does not allow ternary operator on struct types — use if/else instead

Performance Budget

Deployment environments may use headless software rendering with limited GPU power. Stay within these limits:

• - Ray marching main loop: ≤ 128 steps
• Volume sampling / lighting inner loops: ≤ 32 steps
• FBM octaves: ≤ 6 layers
• Total nested loop iterations per pixel: ≤ 1000 (exceeding this freezes the browser)

Quick Recipes

Common effect combinations — complete rendering pipelines assembled from technique modules.

Photorealistic SDF Scene

1. 1. Geometry: sdf-3d (extended primitives) + csg-boolean-operations (cubic/quartic smin)
2. Rendering: ray-marching + normal-estimation (tetrahedron method)
3. Lighting: lighting-model (outdoor three-light model) + shadow-techniques (improved soft shadow) + ambient-occlusion
4. Atmosphere: atmospheric-scattering (height-based fog with sun tint)
5. Post: post-processing (ACES tone mapping) + anti-aliasing (2x SSAA) + camera-effects (vignette)

Organic / Biological Forms

1. 1. Geometry: sdf-3d (extended primitives + deformation operators: twist, bend) + csg-boolean (gradient-aware smin for material blending)
2. Detail: procedural-noise (FBM with derivatives) + domain-warping
3. Surface: lighting-model (subsurface scattering approximation via half-Lambert)

Procedural Landscape

1. 1. Terrain: terrain-rendering + procedural-noise (erosion FBM with derivatives)
2. Texturing: texture-mapping-advanced (biplanar mapping + no-tile)
3. Sky: atmospheric-scattering (Rayleigh/Mie + height fog)
4. Water: water-ocean (Gerstner waves) + lighting-model (Fresnel reflections)

Stylized 2D Art

1. 1. Shapes: sdf-2d (extended library) + sdf-tricks (layered edges, hollowing)
2. Color: color-palette (cosine palettes) + polar-uv-manipulation (kaleidoscope)
3. Polish: anti-aliasing (SDF analytical AA) + post-processing (bloom, chromatic aberration)

Shader Debugging Techniques

Visual debugging methods — temporarily replace your output to diagnose issues.

What to check	Code	What to look for
Surface normals	INLINECODE64	Smooth gradients = correct normals; banding = epsilon too large
Ray march step count

col = vec3(float(steps) / float(MAX_STEPS)); | Red hotspots = performance bottleneck; uniform = wasted iterations |
| Depth / distance | col = vec3(t / MAX_DIST); | Verify correct hit distances |
| UV coordinates | col = vec3(uv, 0.0); | Check coordinate mapping |
| SDF distance field | col = (d > 0.0 ? vec3(0.9,0.6,0.3) : vec3(0.4,0.7,0.85)) * (0.8 + 0.2*cos(150.0*d)); | Visualize SDF bands and zero-crossing |
| Checker pattern (UV) | col = vec3(mod(floor(uv.x*10.)+floor(uv.y*10.), 2.0)); | Verify UV distortion, seams |
| Lighting only | col = vec3(shadow); or col = vec3(ao); | Isolate shadow/AO contributions |
| Material ID | col = palette(matId / maxMatId); | Verify material assignment |