frag-craft

# Frag Craft

Vertex places the point. Fragment paints the pixel. Match the spaces or the look is a lie.

Inspired by gamedev-skills/awesome-gamedev-agent-skills shader-programming (Apache-2.0). Original Grok remake. Complements perf-cut (GPU cost after the look is designed), juice-pass (screen shake/hit-stop — not shader craft), lens-rig (camera), hud-stack, godot-teacher (engine shader node APIs). Gaming only. Not a Godot tutor.

Read `references/shader-rails.md` before you write a look. Fill the three templates under `templates/`.

## When to use

- Vertex→fragment reasoning: which stage owns the transform, which stage owns the color
- UV math: offset, scale, wrap, flip, scroll a texture without fighting engine V-origin
- Common game looks: tint, UV scroll, dissolve (noise threshold + edge band), outline/edge, fresnel rim, vignette
- Uniforms vs varyings (per-draw constants vs interpolated vertex→pixel data)
- Translate a concept between GLSL-style notes and HLSL names — not a vendor material graph dump
- Precision and cheap-vs-dear notes before handing GPU cost to perf-cut

## When NOT to use

- Frame-time budget, pooling, draw-call soup, overdraw as *the* job → use perf-cut (this skill designs the look; perf-cut prices it)
- Screen shake, hit-stop, squash, juice on an action that already fires → use juice-pass
- Camera rig, FOV, follow, shake-as-camera → use lens-rig
- HUD layout / readability / screen stack → use hud-stack
- Godot `gdshader` built-ins, Spatial/CanvasItem node APIs, Unity ShaderLab dumps, Unreal material-node tours → use godot-teacher
- Full particle authoring systems, Niagara graphs, or a whole post-process *stack* as engine settings
- Cheat overlays, wallhacks, X-ray, ESP, see-through walls, aimbots, malware

## Inputs

- The look they want in their words (tint a sprite, burn away a crate, rim a silhouette, darken the screen edge)
- 2D sprite vs 3D surface (outline and fresnel are not the same trick)
- Engine name if they offered it (for *where to look*, never an API dump)
- Target platform: desktop / console / mobile (precision and wrap behavior change)
- Any uniforms they already named (time, tint, amount) — do not invent a whole material library
- Whether they need GLSL-style notes, HLSL names, or both

## Procedure

1. Read `references/shader-rails.md`. Refuse cheat overlays, wallhacks, X-ray, ESP, malware, copied vendor shader dumps, and Godot/Unity/Unreal API tours. Hand GPU cost to perf-cut. Hand shake/hit-stop to juice-pass. Hand camera to lens-rig. Hand HUD layout to hud-stack. Hand engine shader node APIs to godot-teacher.
2. Fill `templates/pipeline-card.md`. Lock vertex vs fragment. Name the coordinate space for positions, normals, and view. List uniforms (per draw) vs varyings (interpolated). If spaces mix, stop and fix that before any effect.
3. Name **one** primary look for this pass (tint, scroll, dissolve, outline, fresnel rim, or vignette). Extra looks wait. A dissolve that also rims and vignettes is three jobs.
4. Fill `templates/effect-sheet.md`. Drive the look with UV math and a small set of uniforms. Prefer `mix` / `step` / `smoothstep` / `clamp` over divergent `if`. Tiny original engine-neutral notes only — GLSL-style with HLSL aliases. No copied tutorial GLSL. No `gdshader` built-in dumps.
5. Fill `templates/verify-shader.md`. Check the look on the target platform: V-origin, wrapping, interpolated-normal length, mobile precision, `discard` vs blend, sample count. If the look is right and the frame is not, that is perf-cut, not more math here.
6. Do not paste vendor shader files, engine include graphs, or a living-artist material clone. Do not write a see-through-wall or ESP pass wearing a "debug" costume.
7. Deliver the three templates. One closing line: this is a look-design pass on the vertex→fragment pipe, not a GPU budget pass and not a Godot tutor.

## Output format

- Pipeline card (stage, spaces, uniforms vs varyings)
- Effect sheet (one look, UV math, original notes, HLSL aliases)
- Verify-shader checklist (platform, precision, visual tests, hand-off)
- One line: shader look pass; not perf-cut, not juice-pass, not godot-teacher

## Safety

- Follow `references/shader-rails.md` with no exceptions.
- Gaming design only. Engine-neutral notes. Not a Godot tutor.
- No cheat overlays, wallhacks, X-ray, ESP, aimbots, malware, or exploit kits.
- No CSAM in mock textures or effect names.
- No copied GLSL/HLSL from tutorials or vendor dumps. Tiny original notes only.

## Stop conditions

- Three templates delivered, or refused for cheats / godot-teacher API tours / GPU budget (perf-cut) / juice (juice-pass) / camera (lens-rig) / HUD layout (hud-stack) / copied vendor dumps