Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add manhvann/codexkit --skill shadergit clone --depth 1 https://github.com/manhvann/codexkitWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/manhvann/codexkit/shader)<a href="https://agentmods.dev/skills/manhvann/codexkit/shader"><img src="https://agentmods.dev/badge/skills/manhvann/codexkit/shader/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/manhvann/codexkit/shader"><img src="https://agentmods.dev/badge/skills/manhvann/codexkit/shader.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00065 | $0.01133 |
| Opus 5.5 | $0.00026 | $0.00453 |
| Sonnet 5.5 | $0.00013 | $0.00227 |
| Haiku 4.5 | $0.00006 | $0.00113 |
Grade A, and why
ck:shader scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.
GLSL Fragment Shaders
Write GPU-accelerated fragment shaders for procedural graphics, textures, and visual effects.
When to Use
- Creating procedural textures (wood, marble, clouds, terrain)
- Drawing shapes with distance fields (SDF)
- Generating patterns, noise, gradients
- Building visual effects and animations
- Writing custom shaders for Three.js, WebGL, Processing
Core Concepts
Fragment shaders execute simultaneously on every pixel. Each thread:
- Receives pixel position via
gl_FragCoord - Returns color via
gl_FragColor(vec4: RGBA 0.0-1.0) - Cannot communicate with other threads (stateless)
Standard Uniforms
uniform float u_time; // Elapsed seconds
uniform vec2 u_resolution; // Canvas size (width, height)
uniform vec2 u_mouse; // Mouse position in pixels
Normalize coordinates: vec2 st = gl_FragCoord.xy / u_resolution;
Essential Functions
| Function | Purpose | Example |
|---|---|---|
mix(a,b,t) |
Linear interpolate | mix(red, blue, 0.5) |
step(edge,x) |
Hard threshold | step(0.5, st.x) |
smoothstep(e0,e1,x) |
Smooth threshold | smoothstep(0.2, 0.8, st.x) |
fract(x) |
Fractional part | fract(st * 3.0) for tiling |
mod(x,y) |
Modulo | mod(st.x, 0.25) |
clamp(x,min,max) |
Constrain value | clamp(col, 0.0, 1.0) |
length(v) |
Vector magnitude | length(st - 0.5) |
distance(a,b) |
Euclidean distance | distance(st, center) |
dot(a,b) |
Dot product | dot(normal, lightDir) |
normalize(v) |
Unit vector | normalize(direction) |
atan(y,x) |
Angle (radians) | atan(st.y-0.5, st.x-0.5) |
sin/cos/pow/abs |
Math | Hardware-accelerated |
Quick Patterns
Circle:
float d = distance(st, vec2(0.5));
float circle = 1.0 - smoothstep(0.2, 0.21, d);
Rectangle:
vec2 bl = step(vec2(0.1), st);
vec2 tr = step(vec2(0.1), 1.0 - st);
float rect = bl.x * bl.y * tr.x * tr.y;
Tiling:
st = fract(st * 4.0); // 4x4 grid
What ships with it
12 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/glsl-cellular-voronoi-worley-noise-patterns.md 3.3 KB
- references/glsl-colors-rgb-hsb-gradients-mixing-color-spaces.md 3.1 KB
- references/glsl-fbm-fractional-brownian-motion-turbulence-octaves.md 3.0 KB
- references/glsl-fundamentals-data-types-vectors-precision-coordinates.md 2.4 KB
- references/glsl-noise-random-perlin-simplex-cellular-voronoi.md 2.8 KB
- references/glsl-pattern-symmetry-truchet-domain-warping.md 2.8 KB
- references/glsl-patterns-tiling-fract-matrices-transformations.md 2.4 KB
- references/glsl-procedural-textures-clouds-marble-wood-terrain.md 3.0 KB
- references/glsl-shader-builtin-functions-complete-api-reference.md 2.9 KB
- references/glsl-shapes-polygon-star-polar-sdf-combinations.md 2.9 KB
- references/glsl-shapes-sdf-circles-rectangles-polar-distance-fields.md 2.4 KB
- references/glsl-shaping-functions-step-smoothstep-curves-interpolation.md 2.8 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 114 lines · 65 tokens per session scan A 5cd90f8c61f4
ck:shader is a skill published in the GitHub repository manhvann/codexkit (89 stars, last pushed 1mo ago), licensed MIT. It adds 65 tokens to every session and 1,133 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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