shadow-mapping

Instructions for adding real-time shadows to the OGPU graphics engine by connecting a depth pass with lighting shaders. Shadow mapping stores the scene from a light's view, then uses that depth data to darken surfaces blocked from the light.

In plain words
What is it for?
Use it to make static or animated meshes cast shadows, add floor contact shadows, support self-shadowing, or add soft edges with PCF filtering.
Why use it?
The engine has no built-in shadow feature, so adding shadows requires wiring together the caster pass, shadow texture, receiver shaders, and JavaScript code.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/oframe/ogpu/shadow-mapping
Any agent
npx skills add oframe/ogpu --skill shadow-mapping
Clone the repo
git clone --depth 1 https://github.com/oframe/ogpu

Made for: Claude Code, Codex.

Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,900 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00104 $0.01900
Opus 5 $0.00052 $0.00950
Sonnet 5 $0.00021 $0.00380
Haiku 4.5 $0.00010 $0.00190

Measured 2d ago against content hash feb643c69230, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

shadow-mapping 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 2d 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.

.claude/skills/shadow-mapping/SKILL.md · 118 lines

How it starts

The opening of the file, as written. The whole thing — 118 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fold shadow mapping into a RenderPipeline

The engine has no shadow primitive. Shadow mapping is two passes you wire by hand: (1) a depth-only caster pass that renders the occluders from the light's POV into a depth RenderTarget, and (2) receivers that sample that depth map with a comparison sampler + PCF and darken their lighting. There is no shader-chunk system — integration means copying the WGSL pieces into the target shader and wiring the JS. This skill says which pieces and what breaks silently.

Two canonical, working implementations already in the repo — read the one that matches the geometry:

  • examples/shadowmapping/static geometry (plain vertex attributes). shadow.wgsl caster, mesh.wgsl receiver. The minimal reference.
  • examples/skinninggltf/skinned + IBL character. shadowcaster.wgsl pulls skinned positions from the Skin compute buffer so the cast shadow tracks the animation; skinnedmesh.wgsl receives (self-shadow), floor.wgsl receives (contact shadow). The reference for any compute/skinned/IBL case.

Decide the integration shape

  1. Static geometry (vertex attributes) → caster shader is a vertex-only MVP * position from the light camera. Copy examples/shadowmapping/shadow.wgsl.
  2. Skinned / compute-positioned / displaced geometry → the caster MUST pull position the same way the main vertex stage does (same storage buffer, same @builtin(vertex_index) indexing) or the shadow detaches from the animated mesh. Copy examples/skinninggltf/shadowcaster.wgsl.
  3. IBL-only / ambient-only shader (no punctual light) → there is nothing for a shadow to occlude. Add a directional light gated by the shadow factor, or the "shadow" does nothing visible. See references/folding.md.

The JS wiring (depth target, light camera, caster mesh, shadow uniform, comparison sampler, receiver bindings, two-pass render loop) is the same shape in every case — references/folding.md has the copy-paste blocks.

Read the full file on GitHub · 118 lines

Files

What ships with it

1 file 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.

Changes

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.

  1. 2d ago First seen · 118 lines · 104 tokens per session scan A feb643c69230

Subscribe to this mod's changes

shadow-mapping is a skill published in the GitHub repository oframe/ogpu (138 stars, last pushed 21d ago), licensed Unlicense. It adds 104 tokens to every session and 1,900 once invoked, about $0.0005 per session on Opus 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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